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ISO 32000-1 Document management — Portable document format — Part 1: PDF 1.7 - page 14

Table 298 - Additional entries specific to a 3D annotation (continued)

Key

Type

Value

3DB

rectangle

(Optional) The 3D view box, which is the rectangular area in which the 3D

artwork shall be drawn. It shall be within the rectangle specified by the

annotation’s Rect entry and shall be expressed in the annotation’s target

coordinate system (see discussion following this Table).

Default value: the annotation’s Rect entry, expressed in the target

coordinate system. This value is [ -w/2 -h/2 w/2 h/2 ], where w and h are

the width and height, respectively, of Rect.

The 3DB entry specifies the 3D view box, a rectangle in which the 3D artwork appears. The view box shall fit

within the annotation’s rectangle (specified by its Rect entry). It may be the same size, or it may be smaller if

necessary to provide extra drawing area for additional 2D graphics within the annotation.

NOTE 1

Although 3D artwork can internally specify viewport size, conforming readers ignore it in favour of information

provided by the 3DB entry.

The view box shall be specified in the annotation’s target coordinate system, whose origin is at the center of the

annotation’s rectangle. Units in this coordinate system are the same as default user space units. Therefore, the

coordinates of the annotation’s rectangle in the target coordinate system are

[ -w/2 -h/2 w/2 h/2 ]

given w and h as the rectangle’s width and height.

The 3DD entry shall specify a 3D stream that contains the 3D artwork to be shown in the annotation; 3D

streams are described in Section 13.6.3. The 3DD entry may specify a 3D stream directly; it may also specify a

3D stream indirectly by means of a 3D reference dictionary (see 13.6.3.3, "3D Reference Dictionaries"). These

options control whether annotations shall share the same run-time instance of the artwork.

The 3DV entry shall specify the view of the 3D artwork that is displayed when the annotation is activated (as

described in the next paragraph). 3D views, which are described in Section 13.6.4, represent settings for the

virtual camera, such as position, orientation, and projection style. The view specified by 3DV shall be one of the

3D view dictionaries listed in the VA entry in a 3D stream (see Table 300).

The 3DA entry shall be an activation dictionary (see Table 299) that determines how the state of the annotation

and its associated artwork may change.

NOTE 2

These states serve to delay the processing or display of 3D artwork until a user chooses to interact with it.

Such delays in activating 3D artwork can be advantageous to performance.

At any given moment, a 3D annotation shall be in one of two states:

•

Inactive (the default initial state): the annotation displays the annotation’s normal appearance.

NOTE 3

It is typical, though not required, for the normal appearance to be a pre-rendered bitmap of the default view of

the 3D artwork. Conforming writers should provide bitmaps of appropriate resolution for all intended uses of

the document; for example, a high-resolution bitmap for high-quality printing and a screen-resolution bitmap for

on-screen viewing. Optional content (see 8.11, “Optional Content”) may be used to select the appropriate

bitmap for each situation.

•

Active: the annotation displays a rendering of the 3D artwork. This rendering shall be specified by the

annotation’s 3DV entry.

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Table 299 - Entries in a 3D activation dictionary

Key

Type

Value

A

name

(Optional) A name specifying the circumstances under which the

annotation shall be activated. Valid values are:

PO The annotation shall be activated as soon as the page containing

the annotation is opened.

PV The annotation shall be activated as soon as any part of the page

containing the annotation becomes visible.

XA The annotation shall remain inactive until explicitly activated by a

script or user action.

NOTE 1

At any one time, only a single page shall be considered

open in a conforming reader, even though more than one

page may be visible, depending on the page layout.

Default value: XA.

NOTE 2

For performance reasons, documents intended for viewing

in a web browser should use explicit activation (XA). In non-

interactive applications, such as printing systems or

aggregating conforming reader, PO and PV indicate that the

annotation shall be activated when the page is printed or

placed; XA indicates that the annotation shall never be

activated and the normal appearance shall be used.

AIS

name

(Optional) A name specifying the state of the artwork instance upon

activation of the annotation. Valid values are:

I

The artwork shall be instantiated, but real-time script-driven

animations shall be disabled.

L Real-time script-driven animations shall be enabled if present; if

not, the artwork shall be instantiated.

Default value: L.

NOTE 3

In non-interactive conforming readers, the artwork shall be

instantiated and scripts shall be disabled.

D

name

(Optional) A name specifying the circumstances under which the

annotation shall be deactivated. Valid values are:

PC The annotation shall be deactivated as soon as the page is closed.

PI The annotation shall be deactivated as soon as the page

containing the annotation becomes invisible.

XD The annotation shall remain active until explicitly deactivated by a

script or user action.

NOTE 4

At any one time, only a single page shall be considered

open in the conforming reader, even though more than one

page may be visible, depending on the page layout.

Default value: PI.

DIS

name

(Optional) A name specifying the state of the artwork instance upon

deactivation of the annotation. Valid values are U (uninstantiated), I

(instantiated), and L (live). Default value: U.

NOTE 5

If the value of this entry is L, uninstantiation of instantiated

artwork is necessary unless it has been modified.

Uninstantiation is never required in non-interactive

conforming readers.

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Table 299 - Entries in a 3D activation dictionary (continued)

Key

Type

Value

TB

boolean

(Optional; PDF

1.7) A flag indicating the default behavior of an

interactive toolbar associated with this annotation. If true, a toolbar shall

be displayed by default when the annotation is activated and given

focus. If false, a toolbar shall not be displayed by default.

NOTE 6

Typically, a toolbar is positioned in proximity to the

3D

annotation.

Default value: true.

NP

boolean

(Optional; PDF 1.7) A flag indicating the default behavior of the user

interface for viewing or managing information about the 3D artwork.

Such user interfaces can enable navigation to different views or can

depict the hierarchy of the objects in the artwork (the model tree). If true,

the user interface should be made visible when the annotation is

activated. If false, the user interface should not be made visible by

default.

Default value: false

The A and D entries of the activation dictionary determine when a 3D annotation may become active and

inactive. The AIS and DIS entries determine what state the associated artwork shall be in when the annotation

is activated or deactivated. 3D artwork may be in one of three states:

•

Uninstantiated: the initial state of the artwork before it has been used in any way.

•

Instantiated: the state in which the artwork has been read and a run-time instance of the artwork has been

created. In this state, it may be rendered but script-driven real-time modifications (that is, animations) shall

be disabled.

•

Live: the artwork has been instantiated, and it is being modified in real time to achieve some animation

effect. In the case of keyframe animation, the artwork shall be live while it is playing and then shall revert to

an instantiated state when playing completes or is stopped.

NOTE 4

The live state is valid only for keyframe animations or in interactive conforming readers that have JavaScript

support.

If

3D artwork becomes uninstantiated after having been instantiated, later use of the artwork requires re-

instantiation (animations are lost, and the artwork appears in its initial form).

NOTE 5

For this reason, uninstantiation is not necessary unless the artwork has been modified in some way;

consumers may choose to keep unchanged artwork instantiated for performance reasons.

NOTE 6

In non-interactive systems such as printing systems, the artwork cannot be changed. Therefore, applications

may choose to deactivate annotations and uninstantiate artwork differently, based on factors such as memory

usage and the time needed to instantiate artwork, and the TB, NP, D and DIS entries may be ignored.

Multiple 3D annotations may share an instance of 3D artwork, as described in 13.6.3.3, "3D Reference

Dictionaries". In such a case, the state of the artwork instance shall be determined in the following way:

•

If any active annotation dictates (through its activation dictionary) that the artwork shall be live, it shall be

live.

•

Otherwise, if any active annotation dictates that the artwork shall be instantiated, it shall be instantiated.

•

Otherwise (that is, all active annotations dictate that the artwork shall be uninstantiated), the artwork shall

be uninstantiated.

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The rules described in 13.6.2, “3D Annotations”, apply only to active annotations. If all annotations referring to

the artwork are inactive, the artwork nevertheless may be uninstantiated, instantiated, or live 3D Streams.

13.6.3

3D Streams

13.6.3.1

General

The specification of 3D artwork shall be contained in a 3D stream. 3D stream dictionaries, whose entries (in

addition to the regular stream dictionary's entries; see 7.3.7, “Dictionary Objects”) are shown in Table 300, may

provide a set of predefined views of the artwork, as well as a default view. They may also provide scripts and

resources for providing customized behaviours or presentations.

Table 300 - Entries in a 3D stream dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary describes; if

present, shall be 3D for a 3D stream.

Subtype

name

(Required) A name specifying the format of the 3D data contained in

the stream. The only valid value is U3D.

VA

array

(Optional) An array of 3D view dictionaries, each of which specifies a

named preset view of this

3D artwork (see Section

13.6.4,

“3D

Views”).

DV

(various)

(Optional) An object that specifies the default (initial) view of the 3D

artwork. It may be a 3D view dictionary (see Section 13.6.4, “3D

Views”) or one of the following types:

•

An integer specifying an index into the VA array.

•

A text string matching the IN entry in one of the views in the VA

array.

•

A name that indicates the first (F) or last (L) entries in the VA

array.

Default value: 0 (the first entry in the VA array) if VA is present; if VA is

not present, the default view shall be specified within the 3D stream

itself.

Resources

name tree

(Optional) A name tree that maps name strings to objects that may be

used by applications or scripts to modify the default view of the 3D

artwork.

The names in this name tree shall be text strings so as to be encoded

in a way that will be accessible from JavaScript.

OnInstantiate

stream

(Optional) A JavaScript script that shall be executed when the 3D

stream is instantiated.

AN

dictionary

(Optional; PDF

1.7) An animation style dictionary indicating the

method that conforming readers should use to drive keyframe

animations present in this artwork (see 13.6.3.2, "3D Animation Style

Dictionaries").

Default value: an animation style dictionary whose Subtype entry has

a value of None.

The Subtype entry specifies the format of the 3D stream data. The only valid value is U3D, which indicates that

the stream data conforms to the Universal 3D File Format specification (see Bibliography). Conforming readers

shall be prepared to encounter unknown values for Subtype and recover appropriately, which usually means

leaving the annotation in its inactive state, displaying its normal appearance.

NOTE

Conforming readers should follow the approach of falling back to the normal appearance with regard to entries

in other dictionaries that may take different types or values than the ones specified here.

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If present, the VA entry shall be an array containing a list of named present views of the 3D artwork. Each entry

in the array shall be a 3D view dictionary (see 13.6.4, “3D Views”) that shall contain the name of the view and

the information needed to display the view. The order of array elements determines the order in which the

views shall be presented in a user interface. The DV entry specifies the view that shall be used as the initial

view of the 3D artwork.

Default views shall be determined in the following order of precedence: in the annotation dictionary, in the 3D

stream dictionary, or in the 3D artwork contained in the 3D stream.

3D streams contain information that may be used by conforming readers and by scripts to perform animations

and other programmatically-defined behaviours, such as changing the viewing orientation or moving individual

components of the artwork. If present, the OnInstantiate entry shall contain a JavaScript script that shall be

executed by applications that support JavaScript whenever a 3D stream is read to create an instance of the 3D

artwork. The Resources entry shall be a name tree that contains objects that may be used to modify the initial

appearance of the 3D artwork.

13.6.3.2

3D Animation Style Dictionaries

A 3D animation style dictionary (PDF 1.7) specifies the method that conforming readers should use to apply

timeline scaling to keyframe animations. It may also specify that keyframe animations be played repeatedly.

The AN entry of the 3D stream shall specify a 3D animation style dictionary.

A keyframe animation may be provided as the content of a 3D stream dictionary. A keyframe animation

provides key frames and specifies the mapping for the position of geometry over a set period of time (animation

timeline). Keyframe animation is an interactive feature that is highly dependent on the behaviour and controls

provided by the conforming reader.

Table 301 shows the entries in an animation style dictionary.

Table 301 - Entries in an 3D animation style dictionary

Key

Type

Value

Type

name

(Optional). The type of PDF object that this dictionary describes; if present,

shall be 3DAnimationStyle.

Subtype

name

(Optional) The animation style described by this dictionary; see Table 302

for valid values. If an animation style is encountered other than those

described in Table 302, an animation style of None shall be used.

Default value: None

PC

integer

(Optional) An integer specifying the play count for this animation style. A

non-negative integer represents the number of times the animation shall

be played. A negative integer indicates that the animation shall be infinitely

repeated. This value shall be ignored for animation styles of type None.

Default value: 0

TM

number

(Optional) A positive number specifying the time multiplier to be used

when running the animation. A value greater than one shortens the time it

takes to play the animation, or effectively speeds up the animation.

NOTE

This allows authors to adjust the desired speed of animations,

without having to re-author the 3D artwork.

This value shall be ignored for animation styles of type None.

Default value: 1

The descriptions of the animation styles (see Table 302) use the following variables to represent application

time or keyframe settings specified in the 3D artwork.

517

•

t is a point on the animation time line. This value shall be used in conjunction with the keyframe animation

data to determine the state of the 3D artwork.

•

[r₀, r₁] is the keyframe animation time line.

•

t

a is the current time of the conforming reader.

•

t

0 is the time when the conforming reader starts the animation.

•

p is the time it takes to play the keyframe animation through one cycle. In the case of the Linear animation

style, one cycle consists of playing the animation through once from beginning to end. In the case of the

Oscillating animation style, one cycle consists of playing the animation from beginning to end and then

from end to beginning.

•

m is the positive multiplier specified by the TM entry in the animation style dictionary.

Table 302 - Animation styles

None

Keyframe animations shall not be driven directly by the conforming

reader. This value shall be used by documents that are intended to

drive animations through an alternate means, such as JavaScript.

The remaining entries in the animation style dictionary shall be

ignored.

Linear

Keyframe animations shall be driven linearly from beginning to end.

This animation style results in a repetitive playthrough of the

animation, such as in a walking motion.

t = (m(t_a - t₀) + r₀) % (r₁ - r₀)

p = (r₁ - r₀) / m

The “%” symbol indicates the modulus operator.

Oscillating

Keyframe animations shall oscillate along their time range. This

animation style results in a back-and-forth playing of the animation,

such as exploding or collapsing parts.

t = (0.5)(r₁ - r₀)(1 - cos(m(t_a - t₀))) + r₀

p = 2 * pi / m

13.6.3.3

3D Reference Dictionaries

More than one 3D annotation may be associated with the same 3D artwork. There are two ways in which this

association may occur, as determined by the annotation’s 3DD entry (see Table 298):

•

If the 3DD entry specifies a 3D stream, the annotation shall have its own run-time instance of the 3D

artwork. Any changes to the artwork shall be reflected only in this annotation. Other annotations that refer

to the same stream shall have separate run-time instances.

•

If the 3DD entry specifies a 3D reference dictionary (whose entries are shown in Table 303), the annotation

shall have a run-time instance of the 3D artwork with all other annotations that specify the same reference

dictionary. Any changes to the artwork shall be reflected in all such annotations.

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Table 303 - Entries in a 3D reference dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary describes; if

present, shall be 3DRef for a 3D reference dictionary.

3DD

stream

(Required) The 3D stream (see 13.6.3, “3D Streams”) containing the

specification of the 3D artwork.

EXAMPLE

The following example and Figure 66 through Figure 68 show three annotations that use the same 3D

artwork. Object 100 (Annotation 1) has its own run-time instance of the 3D stream (object 200); object

101(Annotation 2) and object 102 (Annotation 3) share a run-time instance through the 3D reference

dictionary (object 201).

100 0 obj

% 3D annotation 1

<< /Type /Annot

/Subtype /3D

/3DD 200 0 R

% Reference to the 3D stream containing the 3D artwork

>>

endobj

101 0 obj

% 3D annotation 2

<< /Type /Annot

/Subtype /3D

/3DD 201 0 R

% Reference to a 3D reference dictionary

>>

endobj

102 0 obj

% 3D annotation 3

<< /Type /Annot

/Subtype /3D

/3DD 201 0 R

% Reference to the same 3D reference dictionary

>>

endobj

200 0 obj

% The 3D stream

<< /Type /3D

/Subtype /U3D

... other keys related to a stream, such as /Length

>>

stream

... U3D data...

endstream

endobj

201 0 obj

% 3D reference dictionary

<< /Type /3DRef

/3DD 200 0 R

% Reference to the actual 3D artwork.

>>

endobj

519

2

Annotation 1

B

2

Annotation 2

B

2

Annotation 3

B

Figure 66 - Default view of artwork

2

Annotation 1

B

Annotation 2

1

A

Annotation 3

B

Figure 67 - Annotation 2 rotated

2

Annotation 1

B

Annotation 2

1

A

2

Annotation 3

B

Figure 68 - Shared artwork (annotations 2 & 3) modified

The figures show how the objects in the Example in 13.5, “Alternate Presentations,” might be used.

Figure 66 shows the same initial view of the artwork in all three annotations. Figure 67 shows the results

of rotating the view of the artwork within Annotation 2. Figure 68 shows the results of manipulating the

artwork shared by Annotation 2 and Annotation 3: they both reflect the change in the artwork because

they share the same run-time instance. Annotation 1 remains unchanged because it has its own run-time

instance.

NOTE

When multiple annotations refer to the same instance of 3D artwork, the state of the instance is determined as

described in 13.6.2, “3D Annotations.”

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13.6.4

3D Views

13.6.4.1

General

A 3D view (or simply view) specifies parameters that shall be applied to the virtual camera associated with a 3D

annotation. These parameters may include orientation and position of the camera, details regarding the

projection of camera coordinates into the annotation’s target coordinate system, and a description of the

background on which the artwork shall be drawn. Starting with PDF 1.7, views may specify how 3D artwork is

rendered, coloured, lit, and cross-sectioned, without the use of embedded JavaScript. Views may also specify

which nodes (three-dimensional areas) of 3D artwork shall be included in a view and whether those nodes are

opaque or invisible.

NOTE 1

Users can manipulate views by performing interactive operations such as free rotation and translation. In

addition, 3D artwork can contain a set of predefined views that the author deems to be of particular interest.

For example, a mechanical drawing of a part may have specific views showing the top, bottom, left, right, front,

and back of an object.

A 3D stream may contain a list of named preset views of the 3D artwork, as specified by the VA entry, which

shall be an array of 3D view dictionaries. The entries in a 3D view dictionary are shown in Table 304.

Table 304 - Entries in a 3D view dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary describes; if

present, shall be 3DView for a 3D view dictionary.

XN

text string

(Required) The external name of the view, suitable for presentation in a

user interface.

IN

text string

(Optional) The internal name of the view, used to refer to the view from

other objects, such as the go-to-3D-view action (see 12.6.4.15, “Go-To-

3D-View Actions”).

MS

name

(Optional) A name specifying how the

3D camera-to-world

transformation matrix shall be determined. The following values are

valid:

M Indicates that the C2W entry shall specify the matrix

U3D Indicates that the view node selected by the U3DPath entry shall

specify the matrix.

If omitted, the view specified in the 3D artwork shall be used.

C2W

array

(Required if the value of MS is M, ignored otherwise) A 12-element 3D

transformation matrix that specifies a position and orientation of the

camera in world coordinates.

U3DPath

text string

or

(Required if the value of MS is U3D, ignored otherwise) A sequence of

array

one or more text strings used to access a view node within the 3D

artwork. The first string in the array is a node ID for the root view node,

and each subsequent string is the node ID for a child of the view node

specified by the prior string. Each view node specifies a

3D

transformation matrix (see 13.6.5, “Coordinate Systems for 3D”); the

concatenation of all the matrices forms the camera-to-world matrix.

Conforming writers should specify only a single text string, not an array,

for this entry.

NOTE

Do not confuse View Nodes with nodes. A View Node is a

parameter in the 3D artwork that specifies a view, while a

node is a PDF dictionary that specifies 3D graphic objects

or collections thereof.

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Table 304 - Entries in a 3D view dictionary (continued)

Key

Type

Value

CO

number

(Optional; used only if MS is present) A non-negative number indicating

a distance in the camera coordinate system along the z axis to the center

of orbit for this view; see discussion following this Table. If this entry is

not present, the conforming reader shall determine the center of orbit.

P

dictionary

(Optional) A projection dictionary (see 13.6.4.2, “Projection Dictionaries”)

that defines the projection of coordinates in the 3D artwork (already

transformed into camera coordinates) onto the target coordinate system

of the annotation.

Default value: a projection dictionary where the value of Subtype is

Perspective, the value of FOV is 90, and all other entries take their

default values.

O

stream

(Optional; meaningful only if MS and P are present) A form XObject that

shall be used to overlay 2D graphics on top of the rendered 3D artwork

(see 13.6.6, “3D Markup”).

BG

dictionary

(Optional) A background dictionary that defines the background over

which the 3D artwork shall be drawn (see 13.6.4.3, “3D Background

Dictionaries”). Default value: a background dictionary whose entries take

their default values.

RM

dictionary

(Optional; PDF 1.7) A render mode dictionary that specifies the render

mode to use when rendering 3D artwork with this view (see 13.6.4.4, “3D

Render Mode Dictionaries”). If omitted, the render mode specified in the

3D artwork shall be used.

LS

dictionary

(Optional; PDF 1.7) A lighting scheme dictionary that specifies the

lighting scheme to be used when rendering 3D artwork with this view

(see 13.6.4.5, “3D Lighting Scheme Dictionaries”). If omitted, the lighting

scheme specified in the 3D artwork shall be used.

SA

array

(Optional; PDF 1.7) An array that contains cross section dictionaries

(see 13.6.4.6,

“3D Cross Section Dictionaries”). Each cross section

dictionary provides parameters for applying a cross section to the 3D

artwork when using this view. An empty array signifies that no cross

sections shall be displayed.

NA

array

(Optional; PDF 1.7; meaningful only if NR is present) An array that

contains 3D node dictionaries (see 13.6.4.7, “3D Node Dictionaries”).

Each node dictionary may contain entries that change the node’s state,

including its opacity and its position in world space. This entry and the

NR entry specify how the state of each node shall be changed.

If a node dictionary is present more than once, only the last such

dictionary (using a depth-first traversal) shall be used.

NR

boolean

(Optional; PDF 1.7) Specifies whether nodes specified in the NA array

shall be returned to their original states (as specified in the 3D artwork)

before applying transformation matrices and opacity settings specified in

the node dictionaries. If true, the artwork’s 3D node parameters shall be

restored to their original states and then the dictionaries specified by the

NA array shall be applied. If false, the dictionaries specified by the NA

array shall be applied to the current states of the nodes.

In addition to the parameters specified by a 3D node dictionary, this flag

should also apply to any runtime parameters used by a conforming

reader.

Default value: false

For any view, the conforming writer may provide 2D content specific to the view, to be drawn on top of the 3D

artwork. The O entry specifies a form XObject that shall be overlaid on the rendered 3D artwork. The

522

coordinate system of the form XObject shall be defined to be the same as the (x, y, 0) plane in the camera

coordinate system (see 13.6.5, “Coordinate Systems for 3D”).

Use of the O entry is subject to the following restrictions.

NOTE 2

Failure to abide by them could result in misalignment of the overlay with the rendered 3D graphics:

• It may be specified only in 3D view dictionaries in which both a camera-to-world matrix (MS

and associated entries) and a projection dictionary (the P entry) are present.

• The form XObject shall be associated with a specific view (not with the camera position de-

fined by the 3D view dictionary). The conforming reader should draw it only when the user

navigates using the 3D view, not when the user happens to navigate to the same orientation

by manual means.

• The confirming reader should draw it only if the user has not invoked any actions that alter the

artwork-to-world matrix.

The CO entry specifies the distance from the camera to the center of orbit for the 3D view, which is the point

around which the camera shall rotate when performing an orbit-style navigation. Figure 69 illustrates camera

positioning when orbiting around the center of orbit.

Center Of Orbit

Figure 69 - Rotation around the center of orbit

NOTE 3

The LS entry allows the lighting of the 3D artwork to be changed without changing the artwork itself. This

enables consumers to view a given piece of 3D artwork with a variety of lighting options without requiring

multiple copies of the 3D artwork stream that differ only in lighting. It also enables artwork with poor lighting to

be corrected in cases where the original content cannot be re-authored. See 13.6.4.5, “3D Lighting Scheme

Dictionaries.”

The SA entry provides cross section information for clipping 3D artwork while its associated view is active. This

allows view authors to be more clear in calling out the intended areas of interest for a particular view, some of

which might otherwise be completely obscured. See 13.6.4.6, “3D Cross Section Dictionaries.”

The NR and NA entries are meant to give a more accurate representation of the 3D artwork at a given state.

These keys give view authors finer granularity in manipulating the artwork to be presented in a particular way.

They also provide a means for returning node parameters to a known state after potential changes by

interactive features such as keyframe animations and JavaScript. See 13.6.4.7, “3D Node Dictionaries.”

13.6.4.2

Projection Dictionaries

A projection dictionary (see Table 305) defines the mapping of 3D camera coordinates onto the target

coordinate system of the annotation. Each 3D view may specify a projection dictionary by means of its P entry.

NOTE

Although view nodes can specify projection information, PDF consumers ignore it in favour of information in

the projection dictionary.

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PDF 1.6 introduces near/far clipping. This type of clipping defines a near plane and a far plane (as shown in

Figure 70). Objects, or parts of objects, that are beyond the far plane or closer to the camera than the near

plane are not drawn. 3D objects shall be projected onto the near plane and then scaled and positioned within

the annotation’s target coordinate system, as described Table 305.

Table 305 - Entries in a projection dictionary

Key

Type

Value

Subtype

name

(Required) The type of projection. Valid values shall be O (orthographic) or P

(perspective).

CS

name

(Optional) The clipping style. Valid values shall be XNF (explicit near/far) or ANF

(automatic near/far). Default value: ANF.

F

number

(Optional; meaningful only if the value of CS is XNF) The far clipping distance,

expressed in the camera coordinate system. No parts of objects whose z

coordinates are greater than the value of this entry are drawn. If this entry is

absent, no far clipping occurs.

N

number

(Meaningful only if the value of CS is XNF; required if the value of Subtype is P)

The near clipping distance, expressed in the camera coordinate system. No

parts of objects whose z coordinates are less than the value of this entry are

drawn. If Subtype is P, the value shall be positive; if Subtype is O, the value

shall be non-negative, and the default value is 0.

FOV

number

(Required if Subtype is P, ignored otherwise) A number between 0 and 180,

inclusive, specifying the field of view of the virtual camera, in degrees. It defines

a cone in 3D space centered around the z axis and a circle where the cone

intersects the near clipping plane. The circle, along with the value of PS, specify

the scaling of the projected artwork when rendered in the 2D plane of the

annotation.

PS

number

(Optional; meaningful only if Subtype is P) An object that specifies the scaling

or name

used when projecting the 3D artwork onto the annotation’s target coordinate

system. It defines the diameter of the circle formed by the intersection of the near

plane and the cone specified by FOV. The value may be one of the following:

•

A positive number that explicitly specifies the diameter as a distance in the

annotation’s target coordinate system.

•

A name specifying that the diameter shall be set to the width (W), height

(H), minimum of width and height (Min), or maximum of width and height

(Max) of the annotation’s 3D view box.

Default value: W.

OS

number

(Optional; meaningful only if Subtype is O) A positive number that specifies the

scale factor to be applied to both the x and y coordinates when projecting onto

the annotation’s target coordinate system (the z coordinate is discarded). Default

value: 1.

OB

name

(Optional; PDF 1.7; meaningful only if Subtype is O) A name that specifies a

strategy for binding (scaling to fit) the near plane’s x and y coordinates onto the

annotation’s target coordinate system. The scaling specified in this entry shall be

applied in addition to the scaling factor specified by the OS entry. The value may

be one of the following:

W

Scale to fit the width of the annotation

H

Scale to fit the height of the annotation

Min

Scale to fit the lesser of width or height of the annotation

Max

Scale to fit the greater of width or height of the annotation

Absolute No scaling should occur due to binding.

Default value: Absolute.

524

The CS entry defines how the near and far planes are determined. A value of XNF means that the N and F

entries explicitly specify the z coordinate of the near and far planes, respectively. A value of ANF for CS means

that the near and far planes shall be determined automatically based on the objects in the artwork.

The Subtype entry specifies the type of projection, which determines how objects are projected onto the near

plane and scaled. The possible values are O for orthographic projection and P for perspective projection.

For orthographic projection, objects shall be projected onto the near plane by simply discarding their z value.

They shall be scaled from units of the near plane’s coordinate system to those of the annotation’s target

coordinate system by the combined factors specified by the OS entry and the OB entry.

For perspective projection, a given coordinate (x, y, z) shall be projected onto the near plane, defining a 2D

coordinate (x₁, y₁) using the following formulas:

=

x× --

x1

z

=

y× --

y1

z

where n is the z coordinate of the near plane.

Scaling with perspective projection is more complicated than for orthographic projection. The FOV entry

specifies an angle that defines a cone centered along the z axis in the camera coordinate system (see Figure

70). The cone intersects with the near plane, forming a circular area on the near plane. Figure 71 shows this

circle and graphics from the position of the camera.

Far Clipping Plane

Near Clipping plane

Objects projected onto near clipping plane

Z axis

Field of View angle

Circle defined by Field of View angle on near clipping plane

Figure 70 - Perspective projection of 3D artwork onto the near plane

FOV circle

Z axis projected onto near plane

Figure 71 - Objects projected onto the near clipping plane, as seen from the position of the camera

525

The PS entry specifies the diameter that this circle will have when the graphics projected onto the near plane

are rendered in the annotation’s 3D view box (see Figure 72). Although the diameter of the circle determines

the scaling factor, graphics outside the circle shall also be displayed, providing they fit within the view box, as

seen in the figure.

Figure 73 shows the entire 3D annotation. In this case, the 3D view box is smaller than the annotation’s

rectangle, which also contains 2D content outside the 3D view box.

3D Annotation’s 3DB box

Z axis projected onto near plane,

aligned with center of 3DB box,

scaled to fit the width of the 3DB box

Figure 72 - Positioning and scaling the near plane onto the annotation’s 3D view box

The Daily News

New Planet

Discovered!

Figure 73 - 3D annotation positioned on the page

13.6.4.3

3D Background Dictionaries

A 3D background dictionary defines the background over which a 3D view shall be drawn.Table 306 shows the

entries in a background dictionary. Currently, only a single opaque colour is supported, where the colour shall

be defined in the DeviceRGB colour space. 3D artwork may include transparent objects; however, there is no

interaction between such objects and objects drawn below the annotation. In effect, the 3D artwork and its

background form a transparency group whose flattened results have an opacity of 1 (see 11, “Transparency”).

NOTE

An annotation’s normal appearance should have the same behaviour with respect to transparency when the

appearance is intended to depict the 3D artwork. This does not apply when the appearance is used for another

purpose, such as a compatibility warning message.

526

Table 306 - Entries in a 3D background dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary describes; if present,

shall be 3DBG for a 3D background dictionary.

Subtype

name

(Optional) The type of background. The only valid value shall be SC (solid

colour), which indicates a single opaque colour. Default value: SC.

CS

name or

(Optional) The colour space of the background. The only valid value shall be

array

the name DeviceRGB. Default value: DeviceRGB.

PDF consumers shall be prepared to encounter other values that may be

supported in future versions of PDF.

C

(various)

(Optional) The colour of the background, in the colour space defined by CS.

Default value: an array [1 1 1] representing the colour white when the value

of CS is DeviceRGB.

EA

boolean

(Optional) If true, the background shall apply to the entire annotation; if

false, the background shall apply only to the rectangle specified by the

annotation’s 3D view box (the 3DB entry in Table 298). Default value: false.

13.6.4.4

3D Render Mode Dictionaries

A 3D render mode dictionary (PDF 1.7) specifies the style in which the 3D artwork shall be rendered.

NOTE 1

Surfaces may be filled with opaque colours, they may be stroked as a “wireframe,” or the artwork may be

rendered with special lighting effects.

NOTE 2

A render mode dictionary enables document authors to customize the rendered appearance of 3D artwork to

suit the needs of the intended consumer, without reauthoring the artwork. For conforming readers concerned

strictly with geometry, complex artwork rendered using the Wireframe or Points style may have much better

performance without the added overhead of texturing and lighting effects. Artwork in a document intended for

print may have a much more integrated feel when using the Illustration render mode style.

The RM entry in the 3D views dictionary may specify a 3D render mode dictionary.

Table 307 shows the entries in a render mode dictionary.

Table 307 - Entries in a render mode dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary

describes; if present, shall be 3DRenderMode.

Subtype

name

(Required) The type of render mode described by this

dictionary; see Table 308 for specific values. If an

unrecognized value is encountered, then this render mode

dictionary shall be ignored.

527

Table 307 - Entries in a render mode dictionary (continued)

Key

Type

Value

AC

array

(Optional) An array that specifies the auxiliary colour that

shall be used when rendering the 3D image. The first entry in

the array shall be a colour space; the subsequent entries

shall be values specifying colour values in that colour space.

The interpretation of this entry depends on the render mode

specified by the Subtype entry, but it is often used to specify

a colour for drawing points or edges.

The only valid colour space shall be DeviceRGB. If a colour

space other than DeviceRGB is specified, this entry shall be

ignored and the default value shall be used.

Default value: [/DeviceRGB 0 0 0] representing the colour

black.

FC

name

or

(Optional) A name or array that specifies the face color to be

array

used when rendering the 3D image. This entry shall be

relevant only when Subtype has a value of Illustration.

If the value of FC is an array, the first entry in the array shall

be a colour space and the subsequent entries shall be values

specifying values in that colour space. The only valid colour

space is DeviceRGB. Any colour space other than

DeviceRGB shall be ignored and the default value shall be

used.

If the value of FC is a name, it shall describe a colour. The

only valid name value shall BG, specifying the current

background colour in use for displaying the artwork. If a name

other than BG is encountered, this entry shall be ignored and

the background colour for the host annotation shall be used

(see Table 189).

Default value: BG

O

number

(Optional) A number specifying the opacity of the added

transparency applied by some render modes, using a

standard additive blend.

Default value: 0.5

CV

number

(Optional) A number specifying the angle, in degrees, that

shall be used as the crease value when determining

silhouette edges. If two front-facing faces share an edge and

the angle between the normals of those faces is greater than

or equal to the crease value, then that shared edge shall be

considered a silhouette edge.

Default value: 45

For render modes that add a level of transparency to the rendering, the O entry specifies the additional opacity

that shall be used. All such transparency effects use a standard additive blend mode.

The CV entry sets the crease value that shall be used when determining silhouette edges, which may be used

to adjust the appearance of illustrated render modes. An edge shared by two faces shall be considered a

silhouette edge if either of the following conditions is met:

•

One face is front-facing and the other is back-facing.

•

The angle between the two faces is greater than or equal to the crease value.

528

Table 308 describes the render modes that may be specified in a render mode dictionary.

Table 308 - Render modes

Mode

Description

Solid

Displays textured and lit geometric shapes. In the case of artwork

that conforms to the Universal 3D File Format specification, these

shapes are triangles. The AC entry shall be ignored.

SolidWireframe

Displays textured and lit geometric shapes (triangles) with single

colour edges on top of them. The colour of these edges shall be

determined by the AC entry.

Transparent

Displays textured and lit geometric shapes (triangles) with an

added level of transparency. The AC entry shall be ignored.

TransparentWireframe

Displays textured and lit geometric shapes (triangles) with an

added level of transparency, with single colour opaque edges on

top of it. The colour of these edges shall be determined by the AC

entry.

BoundingBox

Displays the bounding box edges of each node, aligned with the

axes of the local coordinate space for that node. The colour of the

bounding box edges shall be determined by the AC entry.

TransparentBoundingBox

Displays bounding boxes faces of each node, aligned with the

axes of the local coordinate space for that node, with an added

level of transparency. The colour of the bounding box faces shall

be determined by the FC entry.

TransparentBoundingBoxOutline

Displays bounding boxes edges and faces of each node, aligned

with the axes of the local coordinate space for that node, with an

added level of transparency. The colour of the bounding box

edges shall be determined by the AC entry. The colour of the

bounding boxes faces shall be determined by the FC entry.

Wireframe

Displays only edges in a single colour. The colour of these edges

shall be determined by the AC entry.

ShadedWireframe

Displays only edges, though interpolates their colour between

their two vertices and applies lighting. The AC entry shall be

ignored.

HiddenWireframe

Displays edges in a single colour, though removes back-facing

and obscured edges. The colour of these edges shall be

determined by the AC entry.

Vertices

Displays only vertices in a single colour. The colour of these points

shall be determined by the AC entry.

ShadedVertices

Displays only vertices, though uses their vertex colour and applies

lighting. The AC entry shall be ignored.

Illustration

Displays silhouette edges with surfaces, removes obscured lines.

The colour of these edges shall be determined by the AC entry,

and the colour of the surfaces shall be determined by the FC

entry.

SolidOutline

Displays silhouette edges with lit and textured surfaces, removes

obscured lines. The colour of these edges shall be determined by

the AC entry.

ShadedIllustration

Displays silhouette edges with lit and textured surfaces and an

additional emissive term to remove poorly lit areas of the artwork.

The colour of these edges shall be determined by the AC entry.

529

If a render mode type is encountered other than those described in Table 308, the render mode dictionary

containing that entry shall be ignored by its consumers. This allows future documents using new render modes

to behave consistently with future documents using new 3D view constructs that are ignored by older viewers.

13.6.4.5

3D Lighting Scheme Dictionaries

A 3D lighting scheme dictionary (PDF 1.7) specifies the lighting to apply to 3D artwork. The LS entry in the 3D

view may include a 3D lighting scheme dictionary.

Table 301 shows the entries in a 3D lighting scheme dictionary.

Table 309 - Entries in a 3D lighting scheme dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary

describes; if present, shall be 3DLightingScheme.

Subtype

name

(Required) The style of lighting scheme described by this

dictionary (see Table 310).

Table 310 describes the supported lighting schemes. With the exception of the Artwork lighting style, all the

lights specified in Table 310 are infinite lights (also known as distant lights). Unlike lights from a point source, all

rays from an infinite light source are emitted along a single direction vector. For lights specifying an ambient

term, this term shall be added to the diffuse colour of an object’s material. All colours shall be specified in the

DeviceRGB colour space.

When a style other than Artwork is used, only those lights described shall be present; any lighting described in

the artwork shall not be used.

Table 310 - 3D lighting scheme styles

Scheme

Description

Artwork

Lights as specified in the 3D artwork. This has the same effect as if the 3D

lighting scheme dictionary were omitted.

None

No lights shall be used. That is, lighting specified in the 3D artwork shall be

ignored.

White

Three blue-grey infinite lights, no ambient term

Light 1

Colour: < 0.38, 0.38, 0.45 > Direction: < -2.0, -1.5, -0.5 >

Light 2

Colour: < 0.6, 0.6, 0.67 > Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < 0.5, 0.5, 0.57 > Direction: < -0.5, 0.0, 2.0 >

Day

Three light-grey infinite lights, no ambient term

Light 1

Colour: < 0.5, 0.5, 0.5 >

Direction: < -2.0, -1.5, -.5 >

Light 2

Colour: < 0.8, 0.8, 0.9 >

Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < 0.9, 0.9, 0.9 >

Direction: < 0.02, 0.01, 2.0 >

Night

One yellow, one aqua, and one blue infinite light, no ambient term

Light 1

Colour: < 1, .75, .39 >

Direction: < -2.0, -1.5, -0.5 >

Light 2

Colour: < 0.31, 0.47, 0.55 > Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < .5, .5, 1.0 >

Direction: < 0.0, 0.0, 2.0 >

530

Table 310 - 3D lighting scheme styles (continued)

Scheme

Description

Hard

Three grey infinite lights, moderate ambient term

Light

Colour: < 0.5, 0.5, 0.5 > Direction: < -1.5, -1.5, -1.5 >

Light 2

Colour: < 0.8, 0.8, 0.9 > Direction: < 1.5, 1.5, -1.5 >

Light 3

Colour: < 0.9, 0.9, 0.9 > Direction: < -0.5, 0, 2.0 >

Ambient Colour: < 0.5, 0.5, 0.5 >

Primary

One red, one green, and one blue infinite light, no ambient term

Light 1

Colour: < 1, 0.2, 0.5 >

Direction: < -2, -1.5, -0.5 >

Light 2

Colour: < 0.2, 1.0, 0.5 >

Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < 0, 0, 1 >

Direction: < 0.0, 0.0, 2.0 >

Blue

Three blue infinite lights, no ambient term

Light 1

Colour: < 0.4, 0.4, 0.7 >

Direction: < -2.0, -1.5, -0.5 >

Light 2

Colour: < 0.75, 0.75, 0.95 > Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < 0.7, 0.7, 0.95 > Direction: < 0.0, 0.0, 2.0 >

Red

Three red infinite lights, no ambient term

Light 1

Colour: < 0.8, 0.3, 0.4 >

Direction: < -2.0, -1.5, -0.5 >

Light 2

Colour: < 0.95, 0.5, 0.7 > Direction: < 2.0, 1.1, -2.5 >

Light 3

Colour: < 0.95, 0.4, 0.5 > Direction: < 0.0, 0.0, 2.0 >

Cube

Six grey infinite lights aligned with the major axes, no ambient term

Light 1

Colour: < .4, .4, .4 >

Direction: < 1.0, 0.01, 0.01 >

Light 2

Colour: < .4, .4, .4 >

Direction: < 0.01, 1.0, 0.01 >

Light 3

Colour: < .4, .4, .4 >

Direction: < 0.01, 0.01, 1.0 >

Light 4

Colour: < .4, .4, .4 >

Direction: < -1.0, 0.01, 0.01 >

Light 5

Colour: < .4, .4, .4 >

Direction: < 0.01, -1.0, 0.01 >

Light 6

Colour: < .4, .4, .4 >

Direction: < 0.01, 0.01, -1.0 >

CAD

Three grey infinite lights and one light attached to the camera, no ambient

term

Light 1

Colour: < 0.72, 0.72, 0.81 > Direction: < 0.0, 0.0, 0.0 >

Light 2

Colour: < 0.2, 0.2, 0.2 >

Direction: < -2.0, -1.5, -0.5 >

Light 3

Colour: < 0.32, 0.32, 0.32 > Direction: < 2.0, 1.1, -2.5 >

Light 4

Colour: < 0.36, 0.36, 0.36 > Direction: < 0.04, 0.01, 2.0 >

Headlamp

Single infinite light attached to the camera, low ambient term

Light 1

Colour: < 0.8, 0.8, 0.9 >

Direction: < 0.0, 0.0, 0.0 >

Ambient Colour: < 0.1, 0.1, 0.1 >

NOTE

If a lighting scheme style is encountered other than those described in Table 310, the lighting scheme

dictionary containing that entry shall be ignored. This allows future documents using new lighting schemes to

behave consistently with future documents using new 3D view constructs. That is, the expected behaviour is

for the conforming reader to ignore unrecognized lighting styles and 3D view constructs.

13.6.4.6

3D Cross Section Dictionaries

A 3D cross section dictionary (PDF 1.7) specifies how a portion of the 3D artwork shall be clipped for the

purpose of showing artwork cross sections. The SA entry of a 3D view may specify multiple 3D cross section

dictionaries.

531

NOTE

Cross sections enable conforming readers to display otherwise hidden parts of the artwork. They also allow

users to comment on cross sections, using markup annotations. For example, markup annotations can be

used to apply markup annotations to a cross section or to measure distances in a cross section. If multiple

cross sections are specified for a view, the markup annotations in the view apply to all cross sections in the

view.

Table 311 shows the entries in a 3D cross section dictionary.

Table 311 - Entries in a 3D cross section dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary describes; if present, shall

be 3DCrossSection for a 3D cross section dictionary.

C

array

(Optional) A three element array specifying the center of rotation on the cutting

plane in world space coordinates (see 13.6.5, “Coordinate Systems for 3D”).

Default value: [0 0 0] specifying a cutting plane rotating about the origin of the

world space.

O

array

(Required) A three-element array specifying the orientation of the cutting plane

in world space, where each value represents the orientation in relation to the X,

Y, and Z axes, respectively (see 13.6.5, “Coordinate Systems for 3D”). Exactly

one of the values shall be null, indicating an initial state of the cutting plane

that is perpendicular to the corresponding axis and clipping all geometry on the

positive side of that axis. The other two values shall be numbers indicating the

rotation of the plane, in degrees, around their corresponding axes. The order in

which these rotations are applied shall match the order in which the values

appear in the array.

Default value: [null 0 0] specifying a cutting plane that is perpendicular to the X

axis and coplanar with the Y and Z axes.

PO

number

(Optional) A number in the range [0, 1] indicating the opacity of the cutting

plane using a standard additive blend mode.

Default value: 0.5

PC

array

(Optional) An array that specifies the colour for the cutting plane. The first entry

in the array is a colour space, and the remaining entries are values in that

colour space. The only valid colour space is DeviceRGB. If a colour space

other than DeviceRGB is specified, this entry shall be ignored and the default

value shall be used.

Default value: [/DeviceRGB 1 1 1] representing the colour white.

IV

boolean

(Optional) A flag indicating the visibility of the intersection of the cutting plane

with any 3D geometry. If true, then the intersection shall be visible. If false,

then the intersection shall not be visible.

Default value: false

IC

array

(Optional) An array that specifies the colour for the cutting plane’s intersection

with the 3D artwork. The first entry in the array is a colour space, and the

remaining entries are values in that colour space. The only valid colour space

is DeviceRGB. If a colour space other than DeviceRGB is specified, this entry

shall be ignored and the default value shall be used. This entry is meaningful

only if IV is true.

Default value: [/DeviceRGB 0 1 0] representing the colour green.

The C entry specifies the center of the cutting plane. This implies that the plane passes through the center

point, but it is also the point of reference when determining the orientation of the plane.

The O array indicates the orientation of the cutting plane, taking into account its center. The orientation may be

determined by a two-step process:

532

Figure 74 - Rendering of the 3D artwork using View0 (no cross section)

Figure 74 through Figure 78 use world coordinates whose origin is the center of the cube. The axes illustrated

in each diagram show the relative orientation of the world coordinate axes, not the actual position of those

axes. These axes are not part of the 3D artwork used in this example.

Figure 75 - Rendering of the 3D artwork using View1

(cross section perpendicular to the x axis)

Figure 75 shows the cross section specified for the 3DView that references CrossSection1. The illustration

shows the edges of the cutting plane ending at the edges of the annotation’s rectangle. This cross section

specifies a plane with the following characteristics:

•

Includes the world art origin: /C [0 0 0]

•

Perpendicular to the X axis and parallel to the Y and Z axes: /O [ null 0 0]

•

Opacity of the cutting plane is 35%: /PO 0.35

535

•

Colour of the cutting plane is light blue: /PC [/DeviceRGB 0.75 0.86 1]

•

Intersection of the cutting plane with the object is visible: /IV true

•

Colour of the intersection of the cutting plane and the object is green:

/IC [/DeviceRGB 0 1 0]

Figure 76 - Rendering of the 3D artwork using View2

(cross section rotated around the y axis by -30 degrees)

Figure 76 shows the cross section specified for the 3DView that references CrossSection2. This cross section

specifies a plane that differs from the one specified in CrossSection1 (Figure 75) in the following way:

•

Perpendicular to the X axis, rotated -30 degrees around the Y axis, and parallel to the Z axis: /O [ null -30 0]

Figure 77 - Rendering of the 3D artwork using View3

(cross section rotated around the z axis by 30 degrees)

536

Figure 77 shows the cross section specified for the 3DView that references CrossSection3. This cross section

specifies a plane that differs from the one specified in CrossSection1 (Figure 75) in the following way:

•

Perpendicular to the X axis, parallel to the Y axis, and rotated 30 degrees around the Z axis: /O [ null 0 30]

Figure 78 - Rendering of the 3D artwork using View4

(cross section rotated around the y axis by -30 degrees and around the z axis by 30 degrees)

Figure 78 shows the cross section specified for the 3DView that references CrossSection4. This cross section

specifies a plane that differs from the one specified in CrossSection1 (Figure 75) in the following way:

•

Perpendicular to the X axis, rotated -30 degrees around the Y axis, and rotated 30 degrees around the Z

axis: /O [ null -30 30]

13.6.4.7

3D Node Dictionaries

A 3D view may specify a 3D node dictionary (PDF 1.7), which specifies particular areas of 3D artwork and the

opacity and visibility with which individual nodes shall be displayed. The 3D artwork shall be contained in the

parent 3D stream object. The NA entry of the 3D views dictionary may specify multiple 3D node dictionaries for

a particular view.

NOTE 1

While many PDF dictionaries reference 3D artwork in its entirety, it is often useful to reference 3D artwork at a

more granular level. This enables properties such as visibility, opacity, and orientation to be applied to subsets

of the 3D artwork. These controls enable underlying nodes to be revealed, by making the overlying nodes

transparent or by moving them out of the way.

NOTE 2

Do not confuse nodes with view nodes. A node is a PDF dictionary that specifies an area in 3D artwork, while

a view node is a parameter in the 3D artwork that specifies a view.

Table 312 shows the entries in a 3D node dictionary.

537

Table 312 - Entries in a 3D node dictionary

Key

Type

Value

Type

name

(Optional) The type of PDF object that this dictionary

describes; if present, shall be

3DNode for a 3D node

dictionary.

N

text string

(Required) The name of the node being described by the

node dictionary. If the Subtype of the corresponding 3D

Stream is U3D, this entry corresponds to the field Node block

name, as described in the Universal

3D file format

specification (see Bibliography). In the future, nodes may be

described using other 3D conventions.

NOTE

When comparing this entry to node names for a

particular convention

(such as Universal 3D),

conforming readers shall translate between the

PDF text encoding used by PDF and the

character encoding specified in the 3D stream.

O

number

(Optional) A number in the range [0, 1] indicating the opacity

of the geometry supplied by this node using a standard

additive blend mode.

If this entry is absent, the viewer shall use the opacity

specified for the parent node or for the

3D artwork (in

ascending order).

V

boolean

(Optional) A flag indicating the visibility of this node. If true,

then the node is visible. If false, then the node shall not be

visible.

If this entry shall be absent, the viewer shall use the visibility

specified for the parent node or for the

3D artwork (in

ascending order).

M

array

(Optional) A

12-element

3D transformation matrix that

specifies the position and orientation of this node, relative to

its parent, in world coordinates

(see

13.6.5,

“Coordinate

Systems for 3D”).

The N entry specifies which node in the 3D stream corresponds to this node dictionary.

The O entry describes the opacity that shall be used when rendering this node, and the V entry shall determine

whether or not the node is rendered at all. While a node with an opacity of 0 shall be rendered in the same way

as a non-visible node, having a separate value for the visibility of a node allows interactive conforming readers

to show/hide partially transparent nodes, without overwriting the intended opacity of those nodes.

The M entry specifies the node’s matrix relative to its parent, in world coordinates. If an hierarchy of nodes is

intended to be repositioned while still maintaining its internal structure, then only the node at the root of the

hierarchy needs to be adjusted.

EXAMPLE

The following example shows a 3D view specifying an array of node parameters.

3 0 obj

% Default node params with all shapes visible and opaque

[

<< /Type /3DNode

/N (Sphere)

/O 1

/V true

/M [...]>>

<< /Type /3DNode

/N (Cone)

/O 1

/V true >>

538

Figure 79 - Rendering of the 3D artwork using View1 (all shapes visible and opaque)

Figure 79 shows a view whose node array includes three nodes, all of which shall be rendered with the

appearance opaque (/O 1) and visible (/V true).

Figure 80 - Rendering of the 3D artwork using View2 (the cone is hidden and the sphere is semi-

transparent)

Figure 80 shows a view with a node array that specifies the same three nodes used in Figure 79. These nodes

have the following display characteristics:

•

The node named Sphere is partially transparent (/O 0.5) and visible (/V true)

•

The node named Cone is opaque (/O 1) and invisible (/V false)

•

The node named Cube is opaque (/O 1) and visible (/V true)

540

Table 313 - Entries in an external data dictionary used to markup 3D annotations

Key

Type

Value

Type

name

(Required) The type of PDF object that this dictionary describes; if present,

shall be ExData for an external data dictionary.

Subtype

name

(Required) The type of external data that this dictionary describes; shall be

Markup3D for a 3D comment. The only defined value is Markup3D.

3DA

dictionary or

(Required) The 3D annotation to which this markup annotation applies. The

text string

3D annotation may be specified as a child dictionary or as the name of a 3D

annotation, as specified by its NM entry. In the latter case, the 3D annotation

and the markup annotation shall be on the same page of the document.

3DV

dictionary

(Required) The 3D view that this markup annotation is associated with. The

annotation will be hidden unless this view is currently being used for the 3D

annotation specified by 3DA.

MD5

byte string

(Optional) A 16-byte string that contains the checksum of the bytes of the 3D

stream data that this 3D comment shall be associated with. The checksum

shall be calculated by applying the standard MD5 message-digest algorithm

(described in Internet RFC 1321, The MD5 Message-Digest Algorithm; see

the Bibliography) to the bytes of the stream data. This value shall be used to

determine if artwork data has changed since this 3D comment was created.

In a Markup3D ExData dictionary, the 3DA entry identifies the 3D annotation to which the markup shall be

associated. Even though the markup annotation exists alongside the associated annotation in the page’s

Annots array, the markup may be thought of as a child of the 3DA annotation.

The 3DV entry specifies the markup’s associated 3D view. The markup shall only be printed and displayed

when the specified view is the current view of its parent 3D annotation. This ensures that the proper context is

preserved when the markup is displayed.

NOTE

An equivalent view is not sufficient; if more than one markup specify equivalent views represented by different

objects, the markups will not display simultaneously.

The MD5 entry gives conforming readers a means to detect whether or not the 3D stream of the 3D annotation

specified by 3DA has changed. If the 3D stream has changed, the context provided by the 3DV entry may no

longer apply, and the markup may no longer be useful. Any action taken as a response to such a situation is

dependent on the conforming reader, but a warning shall be issued to the user.

EXAMPLE

The following example shows how markup annotations can be associated with particular views.

2 0 obj

% 3D stream data with two named views

<<

/Type /3D

/Subtype /U3D

/VA [4 0 R 5 0 R]

>>

stream

endstream

endobj

3 0 obj

% 3D annotation

<<

/Type /Annot

/Subtype /3D

/3DD 2 0 R

543

endobj

9 0 obj

% Stamp comment on CommentView2

<<

/Type /Annot

/Subtype /Stamp

/ExData <<

/Type /Markup3D

/3DA 3 0 R

/3DV 5 0 R

>>

>>

endobj

The following illustrations show the placement of markup on annotations on different views of the same 3D

artwork.

Figure 81 - 3D artwork set to its default view

Figure 81 shows the default view, which has no markup annotations.

Figure 82 - 3D artwork set to CommentView1

Figure 82 shows another view to which a markup annotation is applied.

545

Figure 83 - 3D artwork set to CommentView2

Figure 83 shows a view referenced by two markup annotations:

•

A line annotation (/Subtype /Line) with a line dimension intent

(/IT/ LineDimension)

•

A stamp annotation (/Subtype /Stamp)

546

14

Document Interchange

14.1

General

The features described in this clause do not affect the final appearance of a document. Rather, these features

enable a document to include higher-level information that is useful for the interchange of documents among

conforming products:

•

Procedure sets (14.2, “Procedure Sets”) that define the implementation of PDF operators

•

Metadata (14.3, “Metadata”) consisting of general information about a document or a component of a

document, such as its title, author, and creation and modification dates

•

File identifiers (14.4, “File Identifiers”) for reliable reference from one PDF file to another

•

Page-piece dictionaries (14.5, “Page-Piece Dictionaries”) allowing a conforming product to embed private

data in a PDF document for its own use

•

Marked-content operators (14.6, “Marked Content”) for identifying portions of a content stream and

associating them with additional properties or externally specified objects

•

Logical structure facilities (14.7, “Logical Structure”) for imposing a hierarchical organization on the content

of a document

•

Tagged PDF (14.8, “Tagged PDF”), a set of conventions for using the marked content and logical structure

facilities to facilitate the extraction and reuse of a document’s content for other purposes

•

Various ways of increasing the accessibility of a document to users with disabilities (14.9, “Accessibility

Support”), including the identification of the natural language in which it is written (such as English or

Spanish) for the benefit of a text-to-speech engine

•

The Web Capture extension (14.10, “ Web Capture”), which creates PDF files from Internet-based or

locally resident HTML, PDF, GIF, JPEG, and ASCII text files

•

Facilities supporting prepress production workflows (14.11, “Prepress Support”), such as the specification

of page boundaries and the generation of printer’s marks, colour separations, output intents, traps, and

low-resolution proxies for high-resolution images

14.2

Procedure Sets

The PDF operators used in content streams are grouped into categories of related operators called procedure

sets (see Table 314). Each procedure set corresponds to a named resource containing the implementations of

the operators in that procedure set. The ProcSet entry in a content stream’s resource dictionary (see 7.8.3,

“Resource Dictionaries”) shall hold an array consisting of the names of the procedure sets used in that content

stream. These procedure sets shall be used only when the content stream is printed to a PostScript output

device. The names identify PostScript procedure sets that shall be sent to the device to interpret the PDF

operators in the content stream. Each element of this array shall be one of the predefined names shown in

Table 314.

Table 314 - Predefined procedure set

Name

Category of operators

PDF

Painting and graphics state

Text

Text

ImageB

Grayscale images or image masks

547

Table 314 - Predefined procedure set (continued)

Name

Category of operators

ImageC

Colour images

ImageI

Indexed (colour-table) images

Beginning with PDF 1.4, this feature is considered obsolete. For compatibility with existing conforming readers,

conforming writers should continue to specify procedure sets (preferably, all of those listed in Table 314 unless

it is known that fewer are needed). However, conforming readers should not depend on the correctness of this

information.

14.3

Metadata

14.3.1

General

A PDF document may include general information, such as the document’s title, author, and creation and

modification dates. Such global information about the document (as opposed to its content or structure) is

called metadata and is intended to assist in cataloguing and searching for documents in external databases.

Beginning with PDF 1.4, metadata may also be specified for individual components of a document.

Metadata may be stored in a PDF document in either of the following ways:

•

In a metadata stream (PDF 1.4) associated with the document or a component of the document (14.3.2,

“Metadata Streams”)

•

In a document information dictionary associated with the document (14.3.3, “Document Information

Dictionary”)

NOTE

Document information dictionaries is the original way that metadata was included in a PDF file. Metadata

streams were introduced in PDF 1.4 and is now the preferred method to include metadata.

14.3.2

Metadata Streams

Metadata, both for an entire document and for components within a document, may be stored in PDF streams

called metadata streams (PDF 1.4).

NOTE 1

Metadata streams have the following advantages over the document information dictionary:

•

PDF-based workflows often embed metadata-bearing artwork as components within larger documents.

Metadata streams provide a standard way of preserving the metadata of these components for

examination downstream. PDF-aware conforming products should be able to derive a list of all metadata-

bearing document components from the PDF document itself.

•

PDF documents are often made available on the Web or in other environments, where many tools routinely

examine, catalogue, and classify documents. These tools should be able to understand the self-contained

description of the document even if they do not understand PDF.

Besides the usual entries common to all stream dictionaries (see Table 5), the metadata stream dictionary shall

contain the additional entries listed in Table 315.

The contents of a metadata stream shall be the metadata represented in Extensible Markup Language (XML).

NOTE 2

This information is visible as plain text to tools that are not PDF-aware only if the metadata stream is both

unfiltered and unencrypted.

548

Table 315 - Additional entries in a metadata stream dictionary

Key

Type

Value

Type

name

(Required) The type of PDF object that this dictionary describes; shall be

Metadata for a metadata stream.

Subtype

name

(Required) The type of metadata stream that this dictionary describes; shall

be XML.

NOTE 3

The format of the XML representing the metadata is defined as part of a framework called the Extensible

Metadata Platform (XMP) and described in the Adobe document XMP: Extensible Metadata Platform (see the

Bibliography). This framework provides a way to use XML to represent metadata describing documents and

their components and is intended to be adopted by a wider class of products than just those that process PDF.

It includes a method to embed XML data within non-XML data files in a platform-independent format that can

be easily located and accessed by simple scanning rather than requiring the document file to be parsed.

A metadata stream may be attached to a document through the Metadata entry in the document catalogue

(see 7.7.2, “Document Catalog”). The metadata framework provides a date stamp for metadata expressed in

the framework. If this date stamp is equal to or later than the document modification date recorded in the

document information dictionary, the metadata stream shall be taken as authoritative. If, however, the

document modification date recorded in the document information dictionary is later than the metadata

stream’s date stamp, the document has likely been saved by a writer that is not aware of metadata streams. In

this case, information stored in the document information dictionary shall be taken to override any semantically

equivalent items in the metadata stream. In addition, PDF document components represented as a stream or

dictionary may have a Metadata entry (see Table 316).

Table 316 - Additional entry for components having metadata

Key

Type

Value

Metadata

stream

(Optional; PDF 1.4) A metadata stream containing metadata for the

component.

In general, any PDF stream or dictionary may have metadata attached to it as long as the stream or dictionary

represents an actual information resource, as opposed to serving as an implementation artifact. Some PDF

constructs are considered implementational, and hence may not have associated metadata.

When there is ambiguity about exactly which stream or dictionary may bear the Metadata entry, the metadata

shall be attached as close as possible to the object that actually stores the data resource described.

NOTE 4

Metadata describing a tiling pattern should be attached to the pattern stream’s dictionary, but a shading should

have metadata attached to the shading dictionary rather than to the shading pattern dictionary that refers to it.

Similarly, metadata describing an ICCBased colour space should be attached to the ICC profile stream

describing it, and metadata for fonts should be attached to font file streams rather than to font dictionaries.

NOTE 5

In tables describing document components in this specification, the Metadata entry is listed only for those in

which it is most likely to be used. Keep in mind, however, that this entry may appear in other components

represented as streams or dictionaries.

•

In addition, metadata may also be associated with marked content within a content stream. This

association shall be created by including an entry in the property list dictionary whose key shall be

Metadata and whose value shall be the metadata stream dictionary. Because this construct refers to an

object outside the content stream, the property list is referred to indirectly as a named resource (see

14.6.2, “Property Lists”).

14.3.3

Document Information Dictionary

The optional Info entry in the trailer of a PDF file (see 7.5.5, “File Trailer”) shall hold a document information

dictionary containing metadata for the document; Table 317 shows its contents. Any entry whose value is not

known should be omitted from the dictionary rather than included with an empty string as its value.

549

Some conforming readers may choose to permit searches on the contents of the document information

dictionary. To facilitate browsing and editing, all keys in the dictionary shall be fully spelled out, not abbreviated.

New keys should be chosen with care so that they make sense to users.

The value associated with any key not specifically mentioned in Table 317 shall be a text string.

Although conforming readers may store custom metadata in the document information dictionary, they may not

store private content or structural information there. Such information shall be stored in the document

catalogue instead (see 7.7.2, “Document Catalog”).

Table 317 - Entries in the document information dictionary

Key

Type

Value

Title

text string

(Optional; PDF 1.1) The document’s title.

Author

text string

(Optional) The name of the person who created the document.

Subject

text string

(Optional; PDF 1.1) The subject of the document.

Keywords

text string

(Optional; PDF 1.1) Keywords associated with the document.

Creator

text string

(Optional) If the document was converted to PDF from another format,

the name of the conforming product that created the original document

from which it was converted.

Producer

text string

(Optional) If the document was converted to PDF from another format,

the name of the conforming product that converted it to PDF.

CreationDate

date

(Optional) The date and time the document was created, in human-

readable form (see 7.9.4, “Dates”).

ModDate

date

(Required if PieceInfo is present in the document catalogue;

otherwise optional; PDF 1.1) The date and time the document was

most recently modified, in human-readable form (see 7.9.4, “Dates”).

Trapped

name

(Optional; PDF 1.3) A name object indicating whether the document

has been modified to include trapping information

(see

14.11.6,

“Trapping Support”):

True

The document has been fully trapped; no further trapping

shall be needed. This shall be the name True, not the

boolean value true.

False

The document has not yet been trapped. This shall be the

name False, not the boolean value false.

Unknown Either it is unknown whether the document has been

trapped or it has been partly but not yet fully trapped; some

additional trapping may still be needed.

Default value: Unknown.

NOTE

The value of this entry may be set automatically by the

software creating the document’s trapping information, or

it may be known only to a human operator and entered

manually.

EXAMPLE

This example shows a typical document information dictionary.

1 0 obj

<<

/Title

( PostScript Language Reference, Third Edition )

/Author ( Adobe Systems Incorporated )

/Creator ( Adobe FrameMaker 5 . 5 . 3 for Power Macintosh® )

/Producer ( Acrobat Distiller 3 . 01 for Power Macintosh )

/CreationDate ( D : 19970915110347 - 08' 00' )

/ModDate ( D : 19990209153925 - 08' 00' )

>>

endobj

550

Table 318 - Entries in a page-piece dictionary

Key

Type

Value

any conforming

dictionary

A data dictionary (see Table 319).

product name or well-

known data type

Table 319 - Entries in an data dictionary

Key

Type

Value

LastModified

date

(Required) The date and time when the contents of the

document, page, or form were most recently modified by this

conforming product.

Private

(any)

(Optional) Any private data appropriate to the conforming

product, typically in the form of a dictionary.

The LastModified entry indicates when this conforming product last altered the content of the page or form. If

the page-piece dictionary contains several data dictionaries, their modification dates can be compared with

those in the corresponding entry of the page object or form dictionary (see Table 30 and Table 95), or the

ModDate entry of the document information dictionary (see Table 317), to ascertain which data dictionary

corresponds to the current content of the page or form. Because some platforms may use only an approximate

value for the date and time or may not deal correctly with differing time zones, modification dates shall be

compared only for equality and not for sequential ordering.

NOTE 2

It is possible for two or more data dictionaries to have the same modification date. Conforming products can

use this capability to define multiple or extended versions of the same data format. For example, suppose that

earlier versions of a conforming product use an data dictionary named PictureEdit, and later versions of the

same conforming product extend the data to include additional items not previously used. The original data

could continue to be kept in the PictureEdit dictionary and the additional items placed in a new dictionary

named PictureEditExtended. This allows the earlier versions of the conforming product to continue to work as

before, and later versions are able to locate and use the extended data items.

14.6

Marked Content

14.6.1

General

Marked-content operators (PDF 1.2) may identify a portion of a PDF content stream as a marked-content

element of interest to a particular conforming product. Marked-content elements and the operators that mark

them shall fall into two categories:

•

The MP and DP operators shall designate a single marked-content point in the content stream.

•

The BMC, BDC, and EMC operators shall bracket a marked-content sequence of objects within the

content stream.

NOTE 1

This is a sequence not simply of bytes in the content stream but of complete graphics objects. Each object is

fully qualified by the parameters of the graphics state in which it is rendered.

NOTE 2

A graphics application, for example, might use marked content to identify a set of related objects as a group to

be processed as a single unit. A text-processing application might use it to maintain a connection between a

footnote marker in the body of a document and the corresponding footnote text at the bottom of the page. The

PDF logical structure facilities use marked-content sequences to associate graphical content with structure

elements (see 14.7.4, “Structure Content”). Table 320 summarizes the marked-content operators.

All marked-content operators except EMC shall take a tag operand indicating the role or significance of the

marked-content element to the conforming reader. All such tags shall be registered with Adobe Systems (see

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