Don't change point classifications of voting points.

filters/NeighborClassifierFilter.cpp

@@ -105,6 +105,13 @@ void NeighborClassifierFilter::prepared(PointTableRef table)
     std::sort(m_domain.begin(), m_domain.end());
 }
 
+
+void NeighborClassifierFilter::ready(PointTableRef)
+{
+    m_newClass.clear();
+}
+
+
 void NeighborClassifierFilter::doOneNoDomain(PointRef &point, PointRef &temp,
     KD3Index &kdi)
 {
@@ -130,9 +137,7 @@ void NeighborClassifierFilter::doOneNoDomain(PointRef &point, PointRef &temp,
     auto oldclass = point.getFieldAs<double>(m_dim);
     auto newclass = pr.first;
     if (pr.second > thresh && oldclass != newclass)
-    {
-        point.setField(m_dim, newclass);
-    }
+        m_newClass[point.pointId()] = newclass;
 }
 
 // update point.  kdi and temp both reference the NN point cloud
@@ -191,6 +196,9 @@ void NeighborClassifierFilter::filter(PointView& view)
             doOne(point_src, point_nn, kdiCand);
         }
     }
+
+    for (auto& p : m_newClass)
+        view.setField(m_dim, p.first, p.second);
 }
 
 } // namespace pdal

filters/NeighborClassifierFilter.hpp

@@ -36,6 +36,7 @@
 
 #include <pdal/Filter.hpp>
 #include <pdal/KDIndex.hpp>
+#include <unordered_map>
 
 extern "C" int32_t NeighborClassifierFilter_ExitFunc();
 extern "C" PF_ExitFunc NeighborClassifierFilter_InitPlugin();
@@ -61,6 +62,7 @@ class PDAL_DLL NeighborClassifierFilter : public Filter
     bool doOne(PointRef& point, PointRef& temp, KD3Index &kdi);
     virtual void filter(PointView& view);
     virtual void initialize();
+    virtual void ready(PointTableRef);
     void doOneNoDomain(PointRef &point, PointRef& temp, KD3Index &kdi);
     PointViewPtr loadSet(const std::string &candFileName, PointTableRef table);
     NeighborClassifierFilter& operator=(
@@ -72,6 +74,7 @@ class PDAL_DLL NeighborClassifierFilter : public Filter
     Dimension::Id m_dim;
     std::string m_dimName;
     std::string m_candidateFile;
+    std::unordered_map<PointId, int> m_newClass;
 };
 
 } // namespace pdal

test/unit/filters/NeighborClassifierFilterTest.cpp

@@ -185,16 +185,22 @@ TEST(NeighborClassifierFilterTest, candidate)
     Stage& r = *(factory.createStage("readers.las"));
     r.setOptions(ro);
 
+    // NeighborClassifier used to be broken because it would change voting point
+    // classifications while it was running. This mean it would create different
+    // classifications if the point order was different.
+    // Randomizing the data should quickly expose this case if it were to reappear.
+    Stage& rfilter = *(factory.createStage("filters.randomize"));
+    rfilter.setInput(r);
+
     std::vector<unsigned int> kvals = {1};
     for (auto &k : kvals) {
 
         Options fo;
-        //fo.add("dimension", "Classification");
         fo.add("candidate", Support::datapath("las/sample_c_thin.las"));
         fo.add("k", k);
 
         Stage& f = *(factory.createStage("filters.neighborclassifier"));
-        f.setInput(r);
+        f.setInput(rfilter);
         f.setOptions(fo);
 
         PointTable table;
@@ -207,15 +213,10 @@ TEST(NeighborClassifierFilterTest, candidate)
 
         stats::Summary::EnumMap NewClassifications = GetClassifications(f);
 
-        //std::cout << "****   K = " << k << "   ****** " << std::endl;
         for (auto& p : OrigClassifications)
         {
             if (p.first == 6)
-            {
                 EXPECT_TRUE(NewClassifications[p.first] == 12441 && OrigClassifications[p.first] == 12525);
-            }
-            //std::cout << "  OrigClassifications["<< p.first << "] = " << OrigClassifications[p.first] <<
-            //" --> " << "NewClassifications[" << p.first << "] = " << NewClassifications[p.first] << std::endl;
         }
     }
 }