Rough attempt at dynamic clipping planes for point clouds

src/geometry.cpp

@@ -36,7 +36,8 @@ static bool plyHasMesh(QString fileName)
 
 //------------------------------------------------------------------------------
 Geometry::Geometry()
-    : m_fileName(),
+    : m_spatialResolution(1.0),
+    m_fileName(),
     m_offset(0,0,0),
     m_centroid(0,0,0),
     m_bbox()

src/geometry.h

@@ -126,6 +126,7 @@ class Geometry : public QObject
                                 double* distance = 0,
                                 std::string* info = 0) const = 0;
 
+
         //--------------------------------------------------
         /// Get file name describing the source of the geometry
         const QString& fileName() const { return m_fileName; }
@@ -143,6 +144,9 @@ class Geometry : public QObject
         /// Get axis aligned bounding box containing the geometry
         const Imath::Box3d& boundingBox() const { return m_bbox; }
 
+        /// Get esimate for the smallest spatial scale of interest
+        float spatialResolution() const { return m_spatialResolution; }
+
     signals:
         /// Emitted at the start of a point loading step
         void loadStepStarted(QString stepDescription);
@@ -155,6 +159,8 @@ class Geometry : public QObject
         void setCentroid(const V3d& centroid) { m_centroid = centroid; }
         void setBoundingBox(const Imath::Box3d& bbox) { m_bbox = bbox; }
 
+        float m_spatialResolution;
+
     private:
         QString m_fileName;
         V3d m_offset;

src/pointarray.cpp

@@ -89,6 +89,31 @@ struct OctreeNode
                                                longitudinalScale, &thisRClosest);
     }
 
+    void spatialResolution(const V3f *const p, float& sumRMin, size_t& count) const
+    {
+        if(endIndex == beginIndex)
+        {
+            for (int i = 0; i < 8; ++i)
+                if(children[i])
+                    children[i]->spatialResolution(p, sumRMin, count);
+        }
+        else
+        {
+            for(size_t i = beginIndex; i < endIndex - 1; i += 1000)
+            {
+                float rMin = FLT_MAX;
+                for(size_t j = i+1; j < endIndex; ++j)
+                {
+                    const float r = (p[j] - p[i]).length2();
+                    rMin = r < rMin ? r : rMin;
+                }
+                sumRMin += sqrtf(rMin);
+                count++;
+            }
+        }
+    }
+
+
     size_t size() const { return endIndex - beginIndex; }
 
     bool isLeaf() const { return beginIndex != endIndex; }
@@ -406,6 +431,13 @@ bool PointArray::loadFile(QString fileName, size_t maxPointCount)
     }
     m_P = (V3f*)m_fields[m_positionFieldIdx].as<float>();
 
+    float rMin = 0;
+    size_t count = 0;
+    m_rootNode.get()->spatialResolution(m_P, rMin, count);
+
+    m_spatialResolution = rMin/count;
+printf("m_spatialResolution = %f\n", m_spatialResolution);
+
     return true;
 }
 

src/view3d.cpp

@@ -105,6 +105,16 @@ void View3D::geometryInserted(const QModelIndex& /*unused*/, int firstRow, int l
     const GeometryCollection::GeometryVec& geoms = m_geometries->get();
     for (int i = firstRow; i <= lastRow; ++i)
         geoms[i]->initializeGL();
+
+    float minSpatialResolution = geoms[0]->spatialResolution();
+    Imath::Box3d bbox = geoms[0]->boundingBox();
+    for(size_t i = 1; i < geoms.size(); ++i)
+    {
+        minSpatialResolution = std::min(minSpatialResolution, geoms[i]->spatialResolution());
+        bbox.extendBy(geoms[i]->boundingBox());
+    }
+    m_camera.setClipNear(minSpatialResolution);
+    m_camera.setClipFar(2*(bbox.max - bbox.min).length());
     geometryChanged();
 }