Abstract Class Name: Colour

Superclass - <Colour Entry>

Subclasses

• <Colour Index>
• <Inline Colour>

Definition

The base class for colours in SEDRIS. <Colours> can be either <Inline Colours> (which are directly attached to coloured objects) or <Colour Indices> (referring to colours in <Colour Tables>).

Primary Page in DRM Diagram:

• 18

Secondary Pages in DRM Diagram:

• 3
• 5
• 8
• 14
• 19
• 23

Example

See concrete subclasses for examples.

FAQs

Where can one find more information on colour in SEDRIS?

See Part 4, Volume 8 Images and Colour Models Technical Guide of the SEDRIS Documentation Set for further information.

Where do RGB values go in all this? How is a single, simple colour represented?

The actual colour values are represented by a single <Primitive Colour> for each <Colour> instance. The location of this <Primitive Colour> depends on whether the <Colour> in question is an <Inline Colour> or a <Colour Index>. See those classes for details.

A single, simple colour is represented as an <Inline Colour>, the colour_mapping of which is set to some variation of PRIMARY_COLOUR, and the <Primitive Colour> of which has only an <Ambient Colour> component specified.

See <Primitive Colour> for further discussion.

How can a data provider represent a colour (e.g., RGB) that has a coefficient (e.g. K)?

The data provider in this example has 2 options.

1. The coefficient can be factored into the colour to create an <Inline Colour>.

2. The colour can be placed in a <Colour Table>, then referenced by a <Colour Index>, the intensity of which is set to the value of the coefficient.

How does one determine how to apply the <Colour> to the object using it? What is the colour_mapping field for?

The colour_mapping field indicates how to apply the <Colour> to the object using it -- which side of the object it applies to, whether it's used for the primary colour, for distance or image blending, etc. (See SE_Colour_Mapping for the details of specific colour mappings).

Incidentally, the colour_mapping field is an SE_Token_Set, rather than a simple enumeration, in order to simplify the consumer's task of identifying what a colour applies to. Its tokens are taken from the SE_Colour_Mapping enumeration.

Is a <Primitive Geometry> required to have a PRIMARY_COLOUR as a component (whether direct or inherited)?

No. Some texture mapping techniques don't require colour to be present on <Polygon>s, so some data providers have no PRIMARY_COLOUR to supply. If a consumer cannot handle the texture mapping technique used in a transmittal, then the consumer will have to choose some appropriate default colour.

Are all combinations of PRIMARY_COLOUR, DISTANCE_BLEND_COLOUR, and IMAGE_BLEND_COLOUR colour mapping valid for a single polygon's OTW front face?

Yes.

Constraints

• <<Colour Mapping Restrictions>>

Composed of (two-way)

• zero or one <Presentation Domain> instance (notes)
• zero or one <Translucency> instance

Component of (two-way)(inherited)

• zero or one <Colour Entry Table> instance

Component of (two-way)

• zero or more <Aggregate Feature> instances
• zero or more <Aggregate Geometry> instances
• zero or more <Attribute Set> instances
• zero or more <Base Vertex> instances
• zero or more <Colour Set> instances
• zero or more <Primitive Feature> instances
• zero or more <Primitive Geometry> instances

Inherited Field Elements

Field Elements

Notes

Composed of Notes

Presentation_Domain

 If present, this component identifies the type of sensor for which
 the given <Colour> instance is applicable.

Fields Notes

colour_mapping

 The set of SE_Colour_Mapping tokens applicable to the given
 <Colour> instance.