Changes between Version 4 and Version 5 of NewDistCalcGeom2Geom
 Timestamp:
 May 31, 2012, 12:48:25 PM (10 years ago)
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NewDistCalcGeom2Geom
v4 v5 1 1 == Explanation of distancecalculation, overview == 2 2 3 The distancecalculation of today is investigating every combination of vertexes and every combination of vertex against edge between vertexesin the two geometries inputed. If there is many vertexes this procedure is very heavy and slow. I have tried to find a way to narrow the distances calculated. The idea is only applicable on geometries not intersecting. Hopefully there will come up some good idea how to solve that. Until then the easiest is to check for intersecting bounding boxes (of subgeoms) and if thats the case pass it back to the old calculation.3 The distancecalculation of today (before PostGIS 1.5) is investigating every combination of vertexes and every combination of vertex against edge in the two geometries inputed. If there is many vertexes this procedure is very heavy and slow. I have tried to find a way to narrow the distances calculated. The idea is only applicable on geometries not intersecting. Hopefully there will come up some good idea how to solve that. Until then the easiest is to check for intersecting bounding boxes (of subgeoms) and if thats the case pass it back to the old calculation. 4 4 5 5 Here I will try to explain the idea in a good way.