This tab has the following components:
Spatial reference system type Specifies the type of spatial reference system, as defined by the SQL/MM standard. Values can be Geographic, Projected, or Engineering (internal use). See srs_type.
Line interpretation Specifies how the spatial reference system interprets lines between points. When the Spatial Reference System Type is Geographic you can select either Round earth or Planar. Otherwise, you can only select Planar. See TYPE clause, CREATE SPATIAL REFERENCE SYSTEM statement.
Round earth The earth is represented using an ellipsoid, providing a twodimensional representation of a threedimensional model of the Earth. Lines between points are interpreted as great elliptic arcs. Given two points on the surface of the Earth, a plane is selected that intersects the two points and the center of the Earth. This plane intersects the Earth, and the line between the two points is the shortest distance along this intersection. This line interpretation is only supported for geographic spatial reference systems.
Planar The Earth (or a portion of the Earth) is represented on a flat, twodimensional place. X and Y are treated as Cartesian coordinates, and lines between points are interpreted as straight lines. For geographic spatial reference systems, the geometric data will be distorted. Depending on the location of an object on the Earth, distortions may affect its area, shape, distance, or direction. This line interpretation is supported for all spatial reference systems and is the only choice for nongeographic spatial reference systems.
Axis order Specifies how the database server interprets points with regards to latitude and longitude. When the Spatial Reference System Type is Geographic, the default axis order is Long./Lat./Z/M; Lat./Long./Z/M is also supported. When the Spatial Reference System Type is Projected or Engineering, the axis order is X/Y/Z/M.
Polygon format Specifies how the database should interpret polygons. Internally, SQL Anywhere formats its polygons counterclockwise; however other products can format their polygons differently. See POLYGON FORMAT clause, CREATE SPATIAL REFERENCE SYSTEM statement.
The following is a list of polygon formats that SQL Anywhere supports:
Counterclockwise The inside of the polygon is on the left side while following ring orientation.
Clockwise The inside of the polygon is on the right side while following ring orientation.
EvenOdd The orientation of rings is ignored and the inside of the polygon is instead determined by looking at the nesting of the rings, with the exterior ring being the largest ring and interior rings being smaller rings inside this ring. A ray is traced from a point within all rings, radiating outward. This is the default format.
Storage format Specifies the format that is used to store the spatial data. See STORAGE FORMAT clause, CREATE SPATIAL REFERENCE SYSTEM statement.
Values include:
Internal SQL Anywhere stores only the normalized representation. This is the default option when the Line Interpretation is Planar.
Original SQL Anywhere stores only the original representation. The original input characteristics can be reproduced, but all operations on the stored values must repeat normalization steps, possibly slowing down the operations.
Mixed SQL Anywhere stores both the original and internal representations, if different. The original representation characteristics can be reproduced and operations on stored values do not need to repeat normalization steps. This is the default option when the Line Interpretation is Round Earth.
Semimajor axis Specifies the distance from center of the earth to the equator. See ELLIPSOID clause, CREATE SPATIAL REFERENCE SYSTEM statement.
Inverse flattening Specifies the inverse flattening ratio. See ELLIPSOID clause, CREATE SPATIAL REFERENCE SYSTEM statement.
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