support simplification without preserving topology in pdal::Polygon a…

…nd reflect in filters.hexbin
PDAL · Oct 7, 2019 · f4628b8 · f4628b8
1 parent 531b21c
commit f4628b8
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Showing 5 changed files with 16 additions and 3 deletions.
diff --git a/doc/stages/filters.hexbin.rst b/doc/stages/filters.hexbin.rst
@@ -117,3 +117,9 @@ threshold
 precision
   Minimum number of significant digits to use in writing out the
   well-known text of the boundary polygon. [Default: 8]
+
+preserve_topology
+  Use GEOS SimplifyPreserveTopology instead of Simplify for polygon simplification with  `smooth` option. [Default: true]
+
+smooth
+  Use GEOS simplify operations to smooth boundary to a tolerance [Default: true]
diff --git a/filters/HexBinFilter.cpp b/filters/HexBinFilter.cpp
@@ -83,6 +83,7 @@ void HexBin::addArgs(ProgramArgs& args)
     m_cullArg = &args.add("hole_cull_area_tolerance", "Tolerance area to "
         "apply to holes before cull", m_cullArea);
     args.add("smooth", "Smooth boundary output", m_doSmooth, true);
+    args.add("preserve_topology", "Preserve topology when smoothing", m_preserve_topology, true);
 }
 
 

diff --git a/filters/HexBinFilter.hpp b/filters/HexBinFilter.hpp
@@ -71,6 +71,7 @@ class PDAL_DLL HexBin : public Filter, public Streamable
     bool m_outputTesselation;
     bool m_doSmooth;
     point_count_t m_count;
+    bool m_preserve_topology;
 
     virtual void addArgs(ProgramArgs& args);
     virtual void ready(PointTableRef table);

diff --git a/pdal/Polygon.cpp b/pdal/Polygon.cpp
@@ -88,7 +88,7 @@ Polygon::Polygon(const BOX3D& box)
 }
 
 
-void Polygon::simplify(double distance_tolerance, double area_tolerance)
+void Polygon::simplify(double distance_tolerance, double area_tolerance, bool preserve_topology)
 {
     throwNoGeos();
 
@@ -114,7 +114,12 @@ void Polygon::simplify(double distance_tolerance, double area_tolerance)
             OGR_G_RemoveGeometry(gdal::toHandle(poly), i, true);
     };
 
-    OGRGeometry *g = m_geom->SimplifyPreserveTopology(distance_tolerance);
+    OGRGeometry *g;
+    if (preserve_topology)
+        g = m_geom->SimplifyPreserveTopology(distance_tolerance);
+    else
+        g = m_geom->Simplify(distance_tolerance);
+
     m_geom.reset(g);
 
     OGRwkbGeometryType t = m_geom->getGeometryType();

diff --git a/pdal/Polygon.hpp b/pdal/Polygon.hpp
@@ -62,7 +62,7 @@ class PDAL_DLL Polygon : public Geometry
 
     OGRGeometryH getOGRHandle();
 
-    void simplify(double distance_tolerance, double area_tolerance);
+    void simplify(double distance_tolerance, double area_tolerance, bool preserve_topology = true);
     double area() const;
     std::vector<Polygon> polygons() const;