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Geospatial measurement sublevels (SPSS Modeler)

Geospatial measurement sublevels

The Geospatial measurement level, which is used with the List storage type, has six sublevels that are used to identify different types of geospatial data.

  • Point. Identifies a specific location (for example, the center of a city).
  • Polygon. A series of points that identifies the single boundary of a region and its location (for example, a county).
  • LineString. Also referred to as a Polyline or just a Line, a LineString is a series of points that identifies the route of a line. For example, a LineString might be a fixed item, such as a road, river, or railway; or the track of something that moves, such as an aircraft's flight path or a ship's voyage.
  • MultiPoint. Used when each row in your data contains multiple points per region. For example, if each row represents a city street, the multiple points for each street can be used to identify every street lamp.
  • MultiPolygon. Used when each row in your data contains several polygons. For example, if each row represents the outline of a country, the US can be recorded as several polygons to identify the different areas such as the mainland, Alaska, and Hawaii.
  • MultiLineString. Used when each row in your data contains several lines. Because lines cannot branch, you can use a MultiLineString to identify a group of lines (for example, data such as the navigable waterways or the railway network in each country).

Restrictions

Be aware of these restrictions when using geospatial data:
  • The coordinate system can affect the format of the data. For example, a Projected coordinate system uses the coordinate values x, y, and (when required) z, whereas a Geographic coordinate system uses the coordinate values longitude, latitude, and (when required) a value for either altitude or depth.
  • A LineString can't cross over itself
  • A Polygon is not self-closing; for each Polygon you must ensure that the first and last points are defined as the same.
  • The direction of the data in a MultiPolygon is important; clockwise indicates a solid form and counterclockwise indicates a hole. For example, if you record an area of a country that contains lakes, the main land area border can be recorded in a clockwise direction and the shape of each lake in a counterclockwise direction.
  • A Polygon can't intersect with itself. An example of this intersection would be if you tried to plot the boundary of the polygon as a continuous line in the form of a figure 8.
  • MultiPolygons can't overlap each other
  • For Geospatial fields, the only relevant storage types are Real and Integer (the default setting is Real)
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