Dissolve (merge geometries)

configuration-examples Dissolve

Dissolving is the process of merging detailed polygon geometries in larger polygon geometries by removing interior segments.

In the GeoDMS this can also be done based on a relational attribute to make polygons for each entry of the domain-unit of this relational attribute.

example

container dissolve
{
   unit<float32> meter    := baseunit('meter', float32);
   unit<fpoint>  point_rd_base;
   unit<fpoint>  point_rd := 
      range(point_rd_base, point(300000[meter],0[meter]), point(625000[meter],280000[meter]));

   unit<uint32> municipality
   : StorageName      = "%SourceDataDir%/CBS/2017/gem_2017.shp"
   , StorageType      = "gdal.vect"
   , StorageReadOnly  = "True"
  {
      attribute<point_rd> geometry (polygon);
      attribute<string>   name;
      attribute<string>   regionname;
      attribute<region>   region_rel := rlookup(regionname, region/values);
   }
   unit<uint32> region := unique(municipality/regionname)
   {
    attribute<point_rd> geometry (polygon) := geos_union_polygon(municipality/geometry, municipality/region_rel);
   }
}

explanation

The example presents two domains: municipality and region. A relation is configured (region_rel) relating the municipality domain unit to the region domain.

The actual dissolving is done in the bold line. The geos_union_polygon is used to dissolve the geometries of a municipality for a region.