Rule Name: Spatial Index Related Organizing Principle

Definition

Objects that are components of a Spatial Index Related Geometry or Spatial Index Related Features shall be fully contained within the spatial extents defined for that <Spatial Index Related> grouping, if the strict_organizing_principle field has value SE_TRUE.

If strict_organizing_principle has value SE_FALSE, no guarantees exist as to how accurately the components were placed into their 'sorted bins' (the branches of the Spatial Index Related Features or Spatial Index Related Geometry.

Rationale

SEDRIS' spatial indexing mechanism was designed to allow the use of spatial indexing even when a few Features or Geometry cross the boundaries of the organizing principles.

Example

1. Consider a Spatial Index Related Geometry with row_count = 1, column_count = 4, row_width = 1000 meters, column_width = 1000 meters. For simplicity, each of the 4 branches of the Spatial Index Related Geometry in this example is a Union of Primitive Geometry.

                        <Spatial Index Related Geometry>
                                       <>
                                       |------- <UTM Location 3D>
                                       |         (0,0,0)
                                       |
        --------------------------------------------------------------
        |                     |                  |                  |
        |                     |                  |                  |
        |- <Geometry          |- <Geometry       |- <Geometry       |- <Geometry
        |   Spatial Index     |   Spatial Index  |   Spatial Index  |Spatial
        |   Data>             |   Data>          |   Data>          |Index Data>
        |   (index = 1)       |   (index = 2)    |   (index = 3)    |(index = 4)
        |                     |                  |                  |
        |                     |                  |                  |
       <Union of          <Union of          <Union of          <Union of
       Primitive          Primitive           Primitive         Primitive
       Geometry>          Geometry>           Geometry>         Geometry>
   

   Since the origin of the collection (its lower-left corner, the UTM Location 3D is (0, 0, 0), the coverages of the branches are:
   

   1. from (0, 0) to (1000, 1000)
   2. from (1000, 0) to (2000, 1000)
   3. from (2000, 0) to (3000, 1000)
   4. from (3000, 0) to (4000, 1000)

   (Note that a Spatial Index Related Geometry does not specify the range of z/height/elevation values.)

   Consider a triangular Polygon in branch #2 of this aggregation, with Vertex Locations (1995,0,0), (2005,0,0) (2005,10,0).

   Since this Polygon crosses the boundary between branch #2 and branch #3, this Spatial Index Related Geometry's strict_organizing_principle must be set to SE_FALSE.

2. Consider a Spatial Index Related Features with row_count = 1, column_count = 4, row_width = 1000 meters, column_width = 500 meters. For simplicity, each of the 4 branches of the Spatial Index Related Features in this example is a Union of Features.

                        <Spatial Index Related Features>
                                       <>
                                       |------- <UTM Location 3D>
                                       |         (0,0,0)
                                       |
        -----------------------------------------------------------
        |                    |                 |                  |
        |                    |                 |                  |
        |- <Feature          |- <Feature       |- <Feature        |- <Feature
        |   Spatial Index    |   Spatial Index |   Spatial Index  |  Spatial
        |   Data>            |   Data>         |   Data>          |  Index Data>
        |   (index = 1)      |   (index = 2)   |   (index = 3)    | (index = 4)
        |                    |                 |                  |
        |                    |                 |                  |
       <Union of          <Union of          <Union of          <Union of
       Features>          Features>           Features>         Features>
   

   Since the origin of the collection (its lower-left corner, the UTM Location 3D is (0, 0, 0), the coverages of the branches are:
   

   1. from (0, 0) to (500, 1000)
   2. from (500, 0) to (1000, 1000)
   3. from (1000, 0) to (1500, 1000)
   4. from (1500, 0) to (2000, 1000)

   (Note that a Spatial Index Related Features does not specify the range of z/height/elevation values.)

   Consider a triangular Areal Feature in branch #2 of this aggregation, consisting of one Regular Feature Face, which in turn has External Feature Face Ring containing 3 Feature Edges as follows:

                          <External Feature Face Ring>
                                    <>
            -----------------------------------------------
            |                      |                      |
            |- <Feature Ring       |- <Feature Ring       |- <Feature Ring
            |  Edge Direction>     |  Edge Direction>     |  Edge Direction>
            |  (forwards=SE_TRUE)  |  (forwards=SE_TRUE)  |  (forwards=SE_TRUE)
            |                      |                      |
       <Feature Edge>         <Feature Edge>         <Feature Edge>
       (from A to B)          (from B to C)          (from C to D)
   

   where A, B, C are Feature Nodes such that

   A's Location is (995, 0) B's Location is (1005, 0) C's Location is (1005, 20)

   Since the Areal Feature thus crosses the boundary between branch #2 and branch #3, the Spatial Index Related Features' strict_organizing_principle must be set to SE_FALSE.

FAQs

Does Spatial Index Related Organizing Principle cover Spatial Index Related Feature Topology?

No. Spatial Index Related Feature Topology implicitly uses a strict organizing principle, since it does not have a flag allowing the data provider to specify that such a principle is not used.