ENH: fixing warnings

Code/BasicFilters/otbPointSetDensityFunction.txx

@@ -48,9 +48,9 @@ PointSetDensityFunction< TPointSet,   TOutput>
 {
 
   typename otb::Image<OutputType,2>::IndexType  index;
-  index[0] = input[0];
-  index[1] = input[1];
-
+  index[0] = static_cast<long int>(input[0]);
+  index[1] = static_cast<long int>(input[1]);
+  
   int accu = 0;
   double surface = M_PI*vcl_pow(2.,static_cast<double>(m_Radius));