Delete Grass GIS Mask removal

Due to GRASS environment destroyed each time computation is done, mask removal is not needed here.

plugins/measure/calc_volume.grass

@@ -4,23 +4,29 @@
 # ------
 # output: prints the volume to stdout
 
+#Import raster ans vector
 v.import input=${area_file} output=polygon_area --overwrite 
 v.import input=${points_file} output=polygon_points --overwrite
 v.buffer -s --overwrite input=polygon_area type=area output=region distance=3 minordistance=3
 r.external input=${dsm_file} output=dsm --overwrite
 
+# Set Grass region to DSM resolution
 g.region rast=dsm
+# Set Grass region to vector bbox
 g.region vector=region
 
-# prevent : removing eventual existing mask
-r.mask -r
+# Create a mask to speed up computation
 r.mask vect=region
 
+# Transfer dsm raster data to vector
 v.what.rast map=polygon_points raster=dsm column=height
 v.to.rast input=polygon_area output=r_polygon_area use=val value=255 --overwrite
 
+# Decimate DSM and generate interpolation of new terrain
 #v.surf.rst --overwrite input=polygon_points zcolumn=height elevation=dsm_below_pile mask=r_polygon_area
 v.surf.bspline --overwrite input=polygon_points column=height raster_output=dsm_below_pile lambda_i=100
 
+# Compute difference between dsm and new dsm
 r.mapcalc expression='pile_height_above_dsm=dsm-dsm_below_pile' --overwrite
+# Volume output from difference
 r.volume -f input=pile_height_above_dsm clump=r_polygon_area