geos_simplify_linestring

Geometric functions geos_simplify_linestring

syntax

  • geos_simplify_linestring(arc_data_item, simplifyfactor)

description

geos_simplify_linestring(arc_data_item, simplifyfactor) results in a data item with the geometry of the arc_data_item, in which the geometric structure is simplified. Near points are combined into a single point. What is near is configured with the simplifyfactor, a Parameter indicating for which distance points are combined. No metric needs to be configured for the simplifyfactor, it uses the Metric of the Coordinate system.

Since GeoDMS 20.23.1 an arc without points, as a null shape record or a selection easily gives, results in an empty arc. Before, such an arc crashed the application with an access violation.

The geos_ prefix of the function name indicates that the implementation of the operator uses geos.

applies to

Since GeoDMS 20.23.1 simplifyfactor must be a parameter with a defined value of 0 or more. An attribute with a value per element was accepted and the value of the first element applied to every element; it now stops with the tolerance must be a parameter. A negative or null value stops with the tolerance must be a defined value of 0 or more; before, a negative value gave an error of the geos library for the geos_ operators, and a null an undefined result for the bg_ operators.

conditions

  1. The composition type of the arc_data_item needs to be arc.
  2. The order of points in the arc_data_item needs to be clockwise for exterior bounds and counterclockwise for holes in polygons (right-hand-rule).

since version

example 

attribute<fpoint> geometry_simplified (arc, road) := geos_simplify_linestring(road/geometry, 10.0);

see also