From 1fa552c1cb27580fb2ee194a60984bf388a22662 Mon Sep 17 00:00:00 2001
From: Andreas Fabri <andreas.fabri@geometryfactory.com>
Date: Wed, 13 Jan 2016 16:16:33 +0100
Subject: [PATCH] Explain usage when called without arguments

---
 CGAL_ImageIO/include/CGAL/Image_3.h               | 4 ----
 Mesh_3/examples/Mesh_3/mesh_3D_gray_vtk_image.cpp | 5 ++++-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/CGAL_ImageIO/include/CGAL/Image_3.h b/CGAL_ImageIO/include/CGAL/Image_3.h
index 2f6fd158759..5a320657dd9 100644
--- a/CGAL_ImageIO/include/CGAL/Image_3.h
+++ b/CGAL_ImageIO/include/CGAL/Image_3.h
@@ -165,10 +165,6 @@ public:
                                          vx,vy,vz,offset));
   }
 
-#if 0
-  bool read_vtk_image_data(vtkImageData*);
-#endif // CGAL_USE_VTK
-
   // implementation in src/CGAL_ImageIO/Image_3.cpp
   void gl_draw(const float point_size,
                const unsigned char r,
diff --git a/Mesh_3/examples/Mesh_3/mesh_3D_gray_vtk_image.cpp b/Mesh_3/examples/Mesh_3/mesh_3D_gray_vtk_image.cpp
index beee8aa4f8f..e7873b75d55 100644
--- a/Mesh_3/examples/Mesh_3/mesh_3D_gray_vtk_image.cpp
+++ b/Mesh_3/examples/Mesh_3/mesh_3D_gray_vtk_image.cpp
@@ -37,7 +37,10 @@ using namespace CGAL::parameters;
 int main(int argc, char* argv[])
 {
   // Loads image
-   
+  if(argc == 1){
+    std::cerr << "Usage:  " << argv[0] << " <directory with dicom data>\n";
+    return 0;
+  }
 
   vtkDICOMImageReader*dicom_reader = vtkDICOMImageReader::New();
   dicom_reader->SetDirectoryName(argv[1]);