added KDE3DResampling Method.

However BoxKDE3D seems to be buggy

math/boxkde/BoxGaus3D.h

@@ -156,8 +156,9 @@ private:
         }
     }
 
-    template<SlicePlane S>
-    void boxBlur1D(const ImageView3D<T>::ConstLineView<S>& src, ImageView3D<T>::LineView<S>& dst, size_t len, size_t r, T iarr)
+
+    template <SlicePlane S>
+    void boxBlur1D(const typename ImageView3D<T>::template ConstLineView<S>& src, typename ImageView3D<T>::template LineView<S>& dst, size_t len, size_t r, T iarr)
     {
         size_t li = 0; // left index
         size_t ri = r; // right index

math/boxkde/Grid3D.h

@@ -164,6 +164,8 @@ public:
 private:
 	_Point3<size_t> add_simple_bin(T x, T y, T z, T w)
     {
+        Assert::isTrue(w > 0, "Weight needs to be postive.");
+
         size_t bin_x = (size_t)((x - bb.getMin().x) / binSizeX);
 		size_t bin_y = (size_t)((y - bb.getMin().y) / binSizeY);
 		size_t bin_z = (size_t)((z - bb.getMin().z) / binSizeZ);

math/boxkde/Image3D.h

@@ -104,6 +104,21 @@ public:
         this->values = tmp;
     }
 
+    // Returns the value at (x,y). Throws if out of bounds.
+    const TValue& at(size_t x, size_t y, size_t z) const
+    {
+        return values[indexFromCoord(x, y, z)];
+    }
+
+    // Returns the value at (x,y) but falls back to default if out of bounds.
+    const TValue& get(size_t x, size_t y, size_t z, TValue dflt = 0) const
+    {
+        if (x >= width || y >= height || z >= depth)
+            return dflt;
+        else
+            return values[indexFromCoord(x, y, z)];
+    }
+
 public:
     typedef LineView<SlicePlane::XY> LineViewXY;
     typedef LineView<SlicePlane::XZ> LineViewXZ;
@@ -205,4 +220,4 @@ template struct ImageView3D<float>;
 //template struct ImageView3D<double>;
 
 template struct Image3D<float>;
-//template struct Image3D<double>;
+//template struct Image3D<double>;