diff --git a/Code/FeatureExtraction/otbGenericRoadExtractionFilter.h b/Code/FeatureExtraction/otbGenericRoadExtractionFilter.h
index e5778c494125cf82ba8c01992781e65c949efbd0..ff2eda4a91908d847750b821bdd17c6fb4392474 100644
--- a/Code/FeatureExtraction/otbGenericRoadExtractionFilter.h
+++ b/Code/FeatureExtraction/otbGenericRoadExtractionFilter.h
@@ -187,7 +187,9 @@ protected:
   /** Destructor */
   ~GenericRoadExtractionFilter() {}
 
-  /** Prepare main computation method */
+  /** Prepare main computation method
+   *  Note : this function isn't called
+   */
   void BeforeGenerateData(void);
 
   /** Main computation method */
diff --git a/Code/FeatureExtraction/otbGenericRoadExtractionFilter.txx b/Code/FeatureExtraction/otbGenericRoadExtractionFilter.txx
index 967152619817b6425bd0e46f9aff8c38c821523d..6ed3e03127b19973aba1dccf5867c09179a5815f 100644
--- a/Code/FeatureExtraction/otbGenericRoadExtractionFilter.txx
+++ b/Code/FeatureExtraction/otbGenericRoadExtractionFilter.txx
@@ -113,6 +113,7 @@ GenericRoadExtractionFilter<TInputImage, TOutputPath>
   m_GradientFilter->SetInput(m_SquareRootImageFilter->GetOutput());
   /** Sigma calculated with the alpha and image resolution parameters */
   m_GradientFilter->SetSigma(static_cast<SigmaType>(m_Alpha * (1.2 / m_Resolution + 1.)));
+  m_GradientFilter->SetUseImageDirection(false);
 
   m_NeighborhoodScalarProductFilter->SetInput(m_GradientFilter->GetOutput());