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The SEDRIS Data Representation Model
APPENDIX A - Classes Attribute Set |
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An instance of this DRM class groups together a set of instances of classes that
An <Attribute Set> instance provides a mechanism for a set of 'attributes' to be explicitly reused by many <Geometry> and / or <Feature> instances.
A number of <Polygon> instances that are all coloured red and rendered using flat shading each contain the same <Attribute Set Index>, which references an <Attribute Set> containing a <Colour> instance specifying red and a <Rendering Properties> instance specifying flat shading.
A number of <Polygon> instances that are all coloured green, have grass texture that is modulated and have an EAC_SURFACE_MATERIAL_TYPE specifying EEC_SRF_MATTY_GRASS. A common <Attribute Set Index> specifies an <Attribute Set> containing:
a <Colour> instance specifying green,
an <Image Mapping Function> instance specifying image_mapping_method = SE_IMG_MAPNG_METH_MODULATE, and
a <Property Value> instance specifying an EAC_SURFACE_MATERIAL_TYPE value of EEC_SRF_MATTY_GRASS.
A number of <Polygon> instances that all have the same electromagnetic properties and are coloured grey. A common <Attribute Set> would contain a <Colour> instance specifying grey and a <Property Table Reference> into a <Property Table> of electromagnetic properties.
A <Feature> is associated with a <Geometry> that has been developed from it. Both reference the same <Attribute Set>, which contains a <Colour> instance, <Image Mapping Function> and <Browse Media>. The <Geometry> would use the <Colour> and <Image Mapping Function> but ignore the <Browse Media>.
Consider a <Feature> instance with a <Data Quality> component, the fictional field of which is set to SE_TRUE. This particular <Feature> instance also has an <Attribute Set Index> component, referencing an <Attribute Set> containing a <Data Quality> instance, the fictional field of which is set to SE_FALSE. Since a <Feature> may contain at most one <Data Quality> instance, the <Data Quality> instance with fictional set to SE_TRUE would be used, as it is contained directly by the <Feature> instance.
Consider a <Geometry> instance with two <Property Table Reference> components, which references an <Attribute Set> that contains another three <Property Table Reference> instances, where all 5 have distinct meanings. As a <Geometry> may contain many <Property Table Reference> instances, all five will be used by the <Geometry> as required. The two that are contained directly will be used first, then the three that are contained in the <Attribute Set>.
Consider a <Polygon> instance with two <Image Mapping Function> components, which references an <Attribute Set> that contains another two. As a <Primitive Geometry> may contain many ordered <Image Mapping Function> instances, all four will be used by the <Polygon> as required. The two that are contained directly will be used in order first, then the three that are contained in the <Attribute Set>, again in order.
A <Union Of Primitive Geometry> contains two <Property Table Reference> instances and references two <Attribute Set> instances. The first <Attribute Set> contains another <Property Table Reference> and and the second <Attribute Set> contains another three <Property Table Reference> instances. As an <Aggregate Geometry> may contain many <Property Table Reference> instances, all six would be used by the <Union Of Primitive Geometry> as required. The two that are contained directly would be used first, then the one that is contained in the first <Attribute Set> and finally the three that are contained in the second <Attribute Set>.
See Part 4, Volume 9 Attribute Inheritance and Context Technical Guide of the SEDRIS Documentation Set for further information.
See the constraint <<Precedence of Attribute Set Index>>.
See the constraint <<Precedence of Attribute Set Index>>.
See the constraint <<Attribute Set Components>>.
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