Table 6.229—DRM_Reference_Vector
Property |
Description |
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Superclass |
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Class |
· <DRM Reference Vector> |
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Subclass |
· none |
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Definition |
An object of this DRM class specifies a unit vector that is used to specify a direction, normal, or axis in the manner specified by the vector_type field. It serves as a unit vector in those coordinate systems with compatible vector space structure. In GD, GM, GEI, GSE, GSM, and SM coordinate systems, it is a vector in the canonical LTP at the location of the <DRM Reference Vector> <DRM Location> component. |
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Example(s) |
· A <DRM Reference Vector> contained by a <DRM Polygon>, representing its geometric normal vector. This would have a vector_type of FACE_NORMAL. · A <DRM Reference Vector> contained by a <DRM Polygon>, representing a normal vector that is used for rendering purposes, i.e., to calculate color and shading when rendering the <DRM Polygon>. This <DRM Reference Vector> would have a vector_type of RENDERING_NORMAL. · A fence modeled as a polygon has radar cross sections that are dependent on aspect angles (azimuth and elevation). These aspect angles are defined with respect to the polygon's normal and its azimuth <DRM Reference Vector>. This <DRM Polygon> (fence) has two <DRM Reference Vector>s (a geometric-normal and an azimuth-reference). The geometric normal is the unit vector perpendicular to the <DRM Polygon> pointing away from it on its outside face and the azimuth reference vector points straight up and is in the plane of the <DRM Polygon>. · A segment of the road has a reflector (actually, a retro-reflector) on it and is modeled as a <DRM Line>. The <DRM Line> has a normal vector that is perpendicular to it and an azimuth reference parallel to it. This is sufficient to describe radar cross sections of the road as a function of aspect angles. However, the normal vector for the infrared bands depends on the orientation of the retro-reflector, not the road. This because radars see the road but IR (or more obviously, car lights) see the retro- reflector. In this example, the <DRM Line> has four <DRM Reference Vector>s (radar-normal, radar-azimuth, ir-normal, and ir-azimuth). · A normal vector used for reflectivity/emissivity calculations. This would have a vector_type of REFLECTIVITY_EMISSIVITY_NORMAL. · A vector specifying the direction an Infinite Light illuminates. This would have a vector_type of LIGHT_DIRECTION. |
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Inherited field elements |
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Field elements |
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Associated to (one-way) (inherited) |
· none |
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Associated to (one-way) |
· none |
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Associated by (one-way) (inherited) |
· none |
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Associated by (one-way) |
· none |
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Associated with (two-way) (inherited) |
· none |
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Associated with (two-way) |
· none |
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Composed of (two-way) (inherited) |
· zero or one <DRM Location> · zero or one DRM_Reference_Vector_Control_Link |
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Composed of (two-way) |
· none |
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Composed of (two-way metadata) (inherited) |
· none |
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Composed of (two-way metadata) |
· none |
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Component of (two-way) (inherited) |
· none |
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Component of (two-way) |
· zero or more <DRM Base Vertex>s · zero or more <DRM Cylindrical Volume Extent>s · zero or more <DRM Ellipse>s · zero or more <DRM Elliptic Cylinder>s · zero or more <DRM Infinite Light>s · zero or more <DRM Line>s · zero or more <DRM Lobe Data>s · zero or more <DRM LSR Transformation Step>s · zero or more <DRM Moving Light Behaviour>s · zero or more <DRM Parallelepiped Volume Extent>s · zero or more <DRM Point>s · zero or more <DRM Polygon>s · zero or more <DRM Union Of Geometry>s |
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Constraints |
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Notes |
none |
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Class diagram |