Generates normal vector field from a vol file using DGtal library.
It will output the embedded vector field (Gaussian convolution on elementary normal vectors) an OFF file, and a TXT normal vector file (theta, phi in degree).
Usage: vol2normalField[options] –input <volFileName> –o <outputFileName>
Allowed options are : 
-h [ --help ]                   display this message.
-i [ --input ] arg              Input vol file.
-o [ --output ] arg             Output filename.
-l [ --level ] arg (=0)         Iso-level for the surface construction.
-s [ --sigma ] arg (=5)         Sigma parameter of the Gaussian kernel.
--exportOriginAndExtremity      exports the origin and extremity of the 
                                vector fields when exporting the vector field
                                in TXT format (useful to be displayed in 
                                other viewer like meshViewer).
-N [ --vectorsNorm ] arg (=1)   set the norm of the exported vectors in TXT 
                                format (when the extremity points are 
                                exported with --exportOriginAndExtremity). By
                                using a negative value you will invert the 
                                direction of the vectors.
-n [ --neighborhood ] arg (=10) Size of the neighborhood for the convolution 
                                (distance on surfel graph).
Example: 
We consider the generation of normal vector field from the Iso-level 40 and export the vectors with a norm = -3 (negative value to invert the normal direction).
$ vol2normalField -i $DGtal/examples/samples/lobster.vol -o lobTreshold40 -l 40 --exportOriginAndExtremity  -N -3
You can use the too meshViewer to display the resulting vector field with the Iso-level surface: 
$ meshViewer -i lobTreshold40.off -f lobTreshold40.txt  --vectorFieldIndex 2 3 4 5 6 7  -n
You should obtain such a result: 
Resulting vector field visualization.
 
 - See also
 - vol2normalField.cpp