diff --git a/plugins/contours/calc_contours.grass b/plugins/contours/calc_contours.grass
deleted file mode 100755
index 870f94bd..00000000
--- a/plugins/contours/calc_contours.grass
+++ /dev/null
@@ -1,50 +0,0 @@
-# dem_file: GeoTIFF DEM containing the surface to calculate contours
-# interval: Contours interval
-# format: OGR output format
-# simplify: Simplify value
-# epsg: target EPSG code
-#
-# ------
-# output: If successful, prints the full path to the contours file. Otherwise it prints "error"
-
-ext=""
-if [ "${format}" = "GeoJSON" ]; then
-    ext="json"
-elif [ "${format}" = "GPKG" ]; then
-    ext="gpkg"
-elif [ "${format}" = "DXF" ]; then
-    ext="dxf"
-elif [ "${format}" = "ESRI Shapefile" ]; then
-    ext="shp"
-fi
-
-#gdal_contour -a elevation -i ${interval} -f GPKG "${dem_file}" contours.gpkg > /dev/null
-#ogr2ogr -dialect SQLite -where "ST_Length(geom) > 4" -simplify ${simplify} -t_srs EPSG:${epsg} -overwrite -f "${format}" output.$$ext contours.gpkg > /dev/null
-
-MIN_CONTOUR_LENGTH=5
-
-r.external input="${dem_file}" output=dem --overwrite
-g.region raster=dem
-r.contour input=dem output=contours step=${interval} --overwrite
-v.generalize --overwrite input=contours output=contours_smooth method=douglas threshold=${simplify}
-v.generalize --overwrite input=contours_smooth output=contours_simplified method=chaiken threshold=1
-v.generalize --overwrite input=contours_simplified output=contours_final method=douglas threshold=${simplify}
-v.edit map=contours_final tool=delete threshold=-1,0,-$$MIN_CONTOUR_LENGTH query=length
-v.out.ogr input=contours_final output=temp.gpkg format="GPKG"
-
-ogr2ogr -t_srs EPSG:${epsg} -overwrite -f "${format}" output.$$ext temp.gpkg > /dev/null
-
-if [ -e "output.$$ext" ]; then
-    # ESRI ShapeFile extra steps to compress into a zip archive
-    # we leverage Python's shutil in this case
-    if [ "${format}" = "ESRI Shapefile" ]; then
-        ext="zip"
-        mkdir contours/
-        mv output* contours/
-        echo "import shutil;shutil.make_archive('output', 'zip', 'contours/')" | python
-    fi
-
-    echo "$$(pwd)/output.$$ext"
-else
-    echo "error"
-fi
diff --git a/plugins/contours/calc_contours.py b/plugins/contours/calc_contours.py
new file mode 100755
index 00000000..39004838
--- /dev/null
+++ b/plugins/contours/calc_contours.py
@@ -0,0 +1,95 @@
+#%module
+#% description: Calculate contours
+#%end
+#%option
+#% key: dem_file
+#% type: string
+#% required: yes
+#% multiple: no
+#% description: GeoTIFF DEM containing the surface to calculate contours
+#%end
+#%option
+#% key: interval
+#% type: double
+#% required: yes
+#% multiple: no
+#% description: Contours interval
+#%end
+#%option
+#% key: format
+#% type: string
+#% required: yes
+#% multiple: no
+#% description: OGR output format
+#%end
+#%option
+#% key: simplify
+#% type: double
+#% required: yes
+#% multiple: no
+#% description: OGR output format
+#%end
+#%option
+#% key: epsg
+#% type: string
+#% required: yes
+#% multiple: no
+#% description: target EPSG code
+#%end
+
+# output: If successful, prints the full path to the contours file. Otherwise it prints "error"
+
+import sys
+from grass.pygrass.modules import Module
+import grass.script as grass
+
+def main():
+    ext = ""
+    if opts['format'] == "GeoJSON":
+        ext = "json"
+    elif opts['format'] == "GPKG":
+        ext = "gpkg"
+    elif opts['format'] == "DXF":
+        ext = "dxf"
+    elif opts['format'] == "ESRI Shapefile":
+        ext = "shp"
+
+    MIN_CONTOUR_LENGTH = 5
+    Module("r.external", input=opts['dem_file'], output="dem", overwrite=True)
+    Module("g.region", raster="dem")
+    Module("r.contour", input="dem", output="contours", step=opts["interval"], overwrite=True)
+    Module("r.generalize", input="contours", output="contours_smooth", method="douglas", threshold=opts["simplify"], overwrite=True)
+    Module("r.generalize", input="contours_smooth", output="contours_simplified", method="chaiken", threshold=1, overwrite=True)
+    Module("r.generalize", input="contours_simplified", output="contours_final", method="douglas", threshold=opts["simplify"], overwrite=True)
+    Module("v.edit", input="contours_final", tool="delete", threshold="-1,0,-%s" % MIN_CONTOUR_LENGTH, query="length")
+    Module("v.out.ogr", input="contours_final", output="temp.gpkg", format="GPKG")
+
+    return 0
+
+if __name__ == "__main__":
+    opts, _ = grass.parser()
+    sys.exit(main())
+
+
+# TODO
+# Running external commands from Python
+# For information on running external commands from Python, see: http://docs.python.org/lib/module-subprocess.html
+
+# Avoid using the older os.* functions. Section 17.1.3 lists equivalents using the Popen() interface, which is more robust (particularly on Windows).
+#
+# ogr2ogr -t_srs EPSG:${epsg} -overwrite -f "${format}" output.$$ext temp.gpkg > /dev/null
+#
+# if [ -e "output.$$ext" ]; then
+#     # ESRI ShapeFile extra steps to compress into a zip archive
+#     # we leverage Python's shutil in this case
+#     if [ "${format}" = "ESRI Shapefile" ]; then
+#         ext="zip"
+#         mkdir contours/
+#         mv output* contours/
+#         echo "import shutil;shutil.make_archive('output', 'zip', 'contours/')" | python
+#     fi
+#
+#     echo "$$(pwd)/output.$$ext"
+# else
+#     echo "error"
+# fi
diff --git a/plugins/measure/calc_volume.py b/plugins/measure/calc_volume.py
index c4e3f9db..8deb2673 100755
--- a/plugins/measure/calc_volume.py
+++ b/plugins/measure/calc_volume.py
@@ -60,30 +60,3 @@ def main():
 if __name__ == "__main__":
     opts, _ = grass.parser()
     sys.exit(main())
-
-#Import raster and 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=1 minordistance=1
-# r.external input=${dsm_file} output=dsm --overwrite
-#
-# # Set Grass region to vector bbox
-# g.region vector=region
-#
-# # 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
-#
-# # Decimate DSM and generate interpolation of new terrain
-# v.surf.rst --overwrite input=polygon_points zcolumn=height elevation=dsm_below_pile
-#
-# # Compute difference between dsm and new dsm
-# r.mapcalc expression='pile_height_above_dsm=dsm-dsm_below_pile' --overwrite
-#
-# # Set region to polygon area to calculate volume
-# g.region vect=polygon_area
-#
-# # Volume output from difference
-# r.volume -f input=pile_height_above_dsm