Detecting sdo_geometries with compound (3-point Arcs) segments

Often I have need to know if the linestrings describing an sdo_geometry line or polygon object contain 3-point arc segments or elements. If a linestring or polygon is described by, or contains, 3-point circular arc elements when: Its sdo_interpretation field in the sdo_elem_info array will contain the values 2 or 4 Or its sdo_etype isRead More

GEOMETRY_COLUMNS for Oracle Spatial

Recently, I had cause to look at the implementation of the OGC/SQLMM Geometry_Columns and Spatial_Ref_Sys metadata views in Oracle. ISO/TC 211, 6.2 Architecture � SQL implementation using Geometry Types, 6.2.1 Overview says: “This standard defines a schema for the management of feature table, Geometry, and Spatial Reference System information in an SQL-implementation with a GeometryRead More

STGeometryTypes: Extracting all geometry type string values from complex geometry

Ever needed to extract a textual description of all geometry types in a single geometry/geography in SQL Server 2008 inluding all sub-elements? Recently I had cause to do so and created the following function that implements this need. Now let’s test it against a selection of all possible geometry types I hope this function isRead More

Vectorising geometry objects in SQL Server 2008

I demonstrated in this article the usefulness of having a vectorising function in one’s spatial database kitbag (there are GetVector functions in my CENTROID and GEOM packages – in particular the GetVector function is vital to the implementation of the algorithm in my CENTROID.SDO_CENTROID function). So, I have also added one to my SQL ServerRead More

STMBR2Geometry/STMBR2Geography functions

Oracle has a polygon geometry type (non-standard) called an optimized rectangle. To define one all one has to do is supply it with the lower-left and upper-right coordinates. This is a much easier thing to do than having to supply 5 coordinates in anti-clockwise order. PostGIS also has a bunch of bounding box functions thatRead More

Extracting geometry types from geometry/geography objects in SQL Server 2008

I have pointed out in another blog that the result of an STIntersection() between two polygon objects could result in an object that is not a polygon or multipolygon. Intersection GEOMETRYCOLLECTION (POLYGON ((100 200, 180 300, 100 300, 100 200)), LINESTRING (100 200, 100 75), POINT (100 0)) Note, the the result is a geometryRead More