Definition

For any quadrant-related organization QTRA, whether a <Quadrant Related Features> or a <Quadrant Related Geometry>,

1. QTRA shall have a <Spatial Extent>.

2. Each branch of QTRA shall comply with the following constraints.

   2.1	Each component representing a quadrant shall have a <Spatial Extent> component. In the case of quadrants represented by <Geometry Model Instance> or <Feature Model Instance> instances, the <Model> being referenced shall have the <Spatial Extent>.
   2.2	The regions defined by the branches shall not overlap; that is, the <Spatial Extent> components of the component hierarchies shall not overlap.
   2.3	The four possible quadrant components' <Spatial Extent> instances shall be defined in their native SRF within the area specified by the QTRA's <Spatial Extent> as follows. Consider the bounding area defined by the <Spatial Extent> of QTRA, as divided into 4 quadrants of equal size.
   	2.3.1 If a branch with SE_QUADRANT_LEFT_FRONT is present, its <Spatial Extent> shall specify the area of the northwest quadrant, such that   2.3.1.1 its eastern boundary aligns with the western boundary of the SE_QUADRANT_RIGHT_FRONT quadrant's <Spatial Extent>, if present, and 2.3.1.2 its southern boundary aligns with the northern boundary of the SE_QUADRANT_LEFT_BACK quadrant's <Spatial Extent>, if present. 2.3.2 If a branch with SE_QUADRANT_RIGHT_FRONT is present, its <Spatial Extent> shall specify the area of the northeast quadrant, such that   2.3.2.1 the <Location> instance representing its northeast corner corresponds to that of QTRA's <Spatial Extent>, 2.3.2.2 its western boundary aligns with the eastern boundary of the SE_QUADRANT_LEFT_FRONT quadrant's <Spatial Extent>, if present, and 2.3.2.3 its southern boundary aligns with the northern boundary of the SE_QUADRANT_RIGHT_BACK quadrant's <Spatial Extent>, if present. 2.3.3 If a branch with SE_QUADRANT_LEFT_BACK is present, its <Spatial Extent> shall specify the area of the southwest quadrant, such that 2.3.3.1 the <Location> instance representing its southwest corner corresponds to that of QTRA's <Spatial Extent>, 2.3.3.2 its eastern boundary aligns with the western boundary of the SE_QUADRANT_RIGHT_BACK quadrant's <Spatial Extent>, if present, and 2.3.3.3 its northern boundary aligns with the southern boundary of the SE_QUADRANT_LEFT_FRONT quadrant's <Spatial Extent>, if present. 2.3.4 If a branch with SE_QUADRANT_RIGHT_BACK is present, its <Spatial Extent> shall specify the area of the southeast quadrant, such that 2.3.4.1 its western boundary aligns with the eastern boundary of the SE_QUADRANT_LEFT_BACK quadrant's <Spatial Extent>, if present, and 2.3.4.2 its northern boundary aligns with the southern boundary of the SE_QUADRANT_RIGHT_FRONT quadrant's <Spatial Extent>, if present.

3. The strict_organizing_principle and unique_descendants field values of QTRA shall be SE_TRUE.

Rationale

1. The quadrant-related organization shall provide a <Spatial Extent>, so that the data provider specifies the bounding area that the quadtree is dividing into quadrants.

2. Each component representing a quadrant shall specify a <Spatial Extent>, because although quadrants are intended to be of equal size, "size" is not invariant under coordinate transformation. The <Spatial Extent> instances are necessary to ensure that the boundaries between quadrants are well-defined when coordinate conversions and transformations are applied.

3. The <Spatial Extent> instances of the branches and the quadrants that they represent shall correspond.

Example

No Example supplied.

FAQs

No FAQs supplied.