Comparison with the OGC Simple Feature Access Definition
The OGC Simple Feature Access definition is a fundamental definition of geospatial features, adapted widely by geospatial software users and vendors alike. The definition is centered around the concept of "simple features".
An OGC Simple feature is defined as "(...) a 2D geometry with linear interpolation between vertices"1. By comparison, a XFM feature is not limited to 2D or linear elements.
This a comparison of the XFM Feature and OGC Simple Feature geometry types:
XFM Feature Geometry Type |
OGC Feature Geometry Type |
Remarks |
---|---|---|
point-cell |
Point |
A XFM point-cell with the default cell is a valid representation of an OGC Point. |
collection-point-cell |
MultiPoint |
- |
point-text |
- |
The OGC Simple Feature Access definition does not support annotations or cartographic text. |
collection-point-text |
- |
See previous remark. |
linestring/curve |
LineString (Line, LinearRing) |
Note that an OGC LineString is a subset of a XFM linestring/curve. If a XFM client is to be compatible with OGC Simple Features, it should exclude placement and modification methods that support arcs, b-splines or curves. |
collection-linestring/curve |
MultiLineString |
An OGC MultiLineString is a subset of a XFM collection-linestring/curve. |
polygon |
Polygon |
An OGC Polygon is a subset of a XFM polygon. |
collection-polygon |
MultiPolygon |
An OGC MultiPolygon is a subset of a XFM collection-polygon. |
OpenGIS(r) Implementation Specification for GeoGraphics Information - Simple feature access - Part 1: Common architecture.