Class Name: Colour Table Group

Superclass - <SEDRIS Abstract Base>

Subclasses

Definition

An instance of this DRM class specifies an interchangeable group of one or more <Colour Table> instances. The primary <Colour Table> in the group is indicated by the primary_table_index. When a reference is made to a <Colour Table> (for example, from an <Colour Index> component of a <Polygon>), the reference identifies the <Colour Table Group> and the index within the <Colour Table>, but not the specific <Colour Table> within the <Colour Table Group>. By definition, a <Colour Index> refers to a <Primitive Colour> from the primary <Colour Table> of the indicated <Colour Table Group>. An alternate <Colour Table> from within the <Colour Table Group> can be chosen at the discretion of the data consumer.

Primary Page in DRM Diagram:

• 14

Secondary Pages in DRM Diagram:

• 10

Example

1. One <Colour Table Group> in the transmittal, and that group has only one <Colour Table> within the group. That <Colour Table> is the one and only <Colour Table> for the entire transmittal.

2. A <Colour Table Group> with two <Colour Table> components, where one <Colour Table> is for normal, Out the Window (OTW) viewing, and the other <Colour Table> exists to change the appearance of the view to represent a view as seen through Night Vision Goggles (NVG).

3. A <Colour Table Group> with 3 <Colour Table> components with the same usage of OTW. Why 3 tables? One <Colour Table> defines the colours as originally created by the data modellers. The second <Colour Table> has different shades of blue for the lakes and skies because a company VIP came through and didn't like the blues that were there. The third <Colour Table> contains yet another set of blues for the lakes, and different shades of green for the trees and tanks, because the customer in charge of the program came through and didn't think the colours were realistic. In this particular example, it's left as an exercise to the data provider to determine which <Colour Table> should be the primary <Colour Table> for the group.

FAQs

Can a transmittal in any way refer to a <Colour Table> in a <Colour Table Group> other than the primary <Colour Table>?

No. The only <Colour_Table> that can be referenced in any <Colour Table Group> is the primary <Colour Table>.

Since they cannot be referenced, why bother to have alternate <Colour Table> instances within a <Colour Table Group>?

Because in real life, many run-time systems do have multiple colour tables they can switch between for various reasons, and these tables should be shared to promote interoperability. See the example section, below.

Constraints

• <<Publishable Object>>
• <<Colour Table Size>>

Associated by (one-way)

• zero or more <Colour Index> instances

Composed of (two-way)

• one or more {ordered} <Colour Table> instances

Composed of (two-way metadata)

• zero or one <Access> instance
• zero or one <Citation> instance
• zero or more <Cross Reference> instances
• zero or one <Description> instance

Component of (two-way)

• one <Colour Table Library> instance

Inherited Field Elements

Field Elements

Notes

Fields Notes

primary_table_index

 The primary_table_index field specifies the primary
 <Colour Table> component of
 the given <Colour Table Group> instance from its
 ordered <Colour Table> components.

table_size

 The table_size field specifies the size of any and all <Colour Table>
 components of the given <Colour Table Group> instance.