ENH : Add a minimum value for reverse projection (not entirely depending on DEM size)

include/otbSARDEMGridImageFilter.txx

@@ -221,6 +221,10 @@ namespace otb
       {
 	margin = std::max(DEMSize[0], DEMSize[1])*0.01; // %1 of the largest dimension
       }
+    if (margin < 100)
+      {
+	margin = 100;
+      }
 
     ImageInSizeType gridStep_SLC;
     gridStep_SLC[0] = m_GridStep[0]*m_MLran;

include/otbSARDEMPolygonsAnalysisImageFilter.txx

@@ -354,6 +354,10 @@ namespace otb
       {
 	margin = std::max(nbColDEM, nbLinesDEM)*0.01; // %1 of the largest dimension
       }
+    if (margin < 100)
+      {
+	margin = 100;
+      }
 
     // Indice for the SAR bloc (determined by the Pipeline)
     ImageOutIndexType id[4] ;