[GRASS-user] v.surf.rst gives warning: Strip exists with insufficient data

Mon Jul 26 10:39:53 PDT 2021

Below is the log of the commands ran through the GRASS GIS in WINDOWS OS.
The commands are to find the volume of the dump pile / cavity in the ground.
I am using everything in the EPSG:4326 CRS.

Input Files:

area_polygon.geojson
```
{"type": "Feature", "properties": {}, "geometry": {"type": "Polygon",
"coordinates": [[[73.31359828017844, 26.222181594890415],
[73.31345181478787, 26.222065660491182], [73.31356935634167,
26.221948621838607], [73.31371520633195, 26.22205185876942],
[73.31359828017844, 26.222181594890415]]]}}
```

polygon_points.geojson
```
{"type": "FeatureCollection", "features": [{"type": "Feature",
"properties": {}, "geometry": {"type": "Point", "coordinates":
[73.31359828017844, 26.222181594890415]}}, {"type": "Feature",
"properties": {}, "geometry": {"type": "Point", "coordinates":
[73.31345181478787, 26.222065660491182]}}, {"type": "Feature",
"properties": {}, "geometry": {"type": "Point", "coordinates":
[73.31356935634167, 26.221948621838607]}}, {"type": "Feature",
"properties": {}, "geometry": {"type": "Point", "coordinates":
[73.31371520633195, 26.22205185876942]}}, {"type": "Feature", "properties":
{}, "geometry": {"type": "Point", "coordinates": [73.31359828017844,
26.222181594890415]}}]}
```

DSM file also in EPSG:4326 CRS, containing elevation information.

```
(Mon Jul 26 22:21:05 2021)

v.import input=C:\\Users\\Administrator\\Downloads\\area_file.geojson
output=polygon_area --overwrite
Check if OGR layer <area_file> contains polygons...
Creating attribute table for layer <area_file>...
Importing 1 features (OGR layer <area_file>)...
-----------------------------------------------------
Registering primitives...
-----------------------------------------------------
Cleaning polygons
-----------------------------------------------------
Breaking polygons...
Breaking polygons (pass 1: select break points)...
Breaking polygons (pass 2: break at selected points)...
-----------------------------------------------------
Removing duplicates...
-----------------------------------------------------
Breaking boundaries...
-----------------------------------------------------
Removing duplicates...
-----------------------------------------------------
Cleaning boundaries at nodes...
-----------------------------------------------------
Merging boundaries...
-----------------------------------------------------
Removing dangles...
-----------------------------------------------------
Building areas...
-----------------------------------------------------
Removing bridges...
-----------------------------------------------------
Registering primitives...
Building areas...
Attaching islands...
-----------------------------------------------------
Finding centroids for OGR layer <area_file>...
-----------------------------------------------------
Writing centroids...
-----------------------------------------------------
1 input polygons
Total area: 341.906 (1 areas)
-----------------------------------------------------
Copying features...
Building topology for vector map <polygon_area at PERMANENT>...
Registering primitives...
Building areas...
Attaching islands...
Attaching centroids...
Input <C:\\Users\\Administrator\\Downloads\\area_file.geojson> successfully
imported without reprojection
(Mon Jul 26 22:21:06 2021) Command finished (1 sec)

(Mon Jul 26 22:21:13 2021)

v.import input=C:\\Users\\Administrator\\Downloads\\points_file.geojson
output=polygon_points --overwrite
Check if OGR layer <points_file> contains polygons...
Creating attribute table for layer <points_file>...
Importing 5 features (OGR layer <points_file>)...
-----------------------------------------------------
Building topology for vector map <polygon_points at PERMANENT>...
Registering primitives...
Input <C:\\Users\\Administrator\\Downloads\\points_file.geojson>
successfully imported without reprojection
(Mon Jul 26 22:21:14 2021) Command finished (0 sec)

(Mon Jul 26 22:21:34 2021)

v.buffer input=polygon_area -s type=area output=region distance=0.001
minordistance=1 --overwrite
Note: In latitude-longitude coordinate system specify distances in degree
unit
WARNING: Option 'minordistance' is not available with GEOS buffering
Buffering areas...
Cleaning buffers...
Building parts of topology...
Building topology for vector map <region at PERMANENT>...
Registering primitives...
Snapping boundaries...
Reading features...
Snap vertices Pass 1: select points
Snap vertices Pass 2: assign anchor vertices
Snap vertices Pass 3: snap to assigned points
Breaking polygons...
Breaking polygons (pass 1: select break points)...
Breaking polygons (pass 2: break at selected points)...
Removing duplicates...
Breaking boundaries...
Removing duplicates...
Cleaning boundaries at nodes
Building topology for vector map <region at PERMANENT>...
Building areas...
Removing dangles...
Removing bridges...
Attaching islands...
Building topology for vector map <region at PERMANENT>...
Attaching islands...
Calculating centroids for all areas...
Generating list of boundaries to be deleted...
Deleting boundaries...
Calculating centroids for areas...
Building topology for vector map <region at PERMANENT>...
Registering primitives...
Building areas...
Attaching islands...
Attaching centroids...
(Mon Jul 26 22:21:34 2021) Command finished (0 sec)

(Mon Jul 26 22:21:49 2021)

r.external input=C:\\Users\\Administrator\\Downloads\\dsm2.tif output=dsm
--overwrite
Reading band 1 of 1...
Link to raster map <dsm> created.
(Mon Jul 26 22:21:50 2021) Command finished (1 sec)

(Mon Jul 26 22:21:56 2021)

g.region raster=dsm

(Mon Jul 26 22:21:56 2021) Command finished (0 sec)

(Mon Jul 26 22:22:00 2021)

g.region vector=region

(Mon Jul 26 22:22:00 2021) Command finished (0 sec)

(Mon Jul 26 22:22:07 2021)

r.mask vector=region

Reading areas...
Writing raster map...
All subsequent raster operations will be limited to the MASK area. Removing
or renaming raster map named 'MASK' will restore raster operations to
normal.
(Mon Jul 26 22:22:08 2021) Command finished (1 sec)

(Mon Jul 26 22:22:14 2021)

v.what.rast map=polygon_points raster=dsm column=height

Column <height> not found in the table <polygon_points>. Creating...
Reading features from vector map...
Update vector attributes...
v.what.rast complete. 5 records updated.
(Mon Jul 26 22:22:14 2021) Command finished (0 sec)

(Mon Jul 26 22:32:57 2021)

v.surf.rst input=polygon_points zcolumn=height elevation=dsm_below_pile
--overwrite
Reading features from vector map ...
WARNING: Strip exists with insufficient data
Ignoring 1 points (too dense)
WARNING: 4 points given for interpolation (after thinning) is less than
given NPMIN=300
WARNING: There are less than 600 points for interpolation. No segmentation
is necessary, to run the program faster set segmax=600 (see manual)
Processing all selected output files will require
29.39 MB of disk space for temp files.
Bitmap mask created
Processing segments...
v.surf.rst complete.
(Mon Jul 26 22:33:00 2021) Command finished (2 sec)

(Mon Jul 26 22:33:06 2021)

r.mapcalc expression=pile_height_above_dsm=dsm-dsm_below_pile --overwrite

(Mon Jul 26 22:33:07 2021) Command finished (1 sec)

(Mon Jul 26 22:33:14 2021)

g.region vector=polygon_area

(Mon Jul 26 22:33:15 2021) Command finished (0 sec)

(Mon Jul 26 22:33:19 2021)

r.volume input=pile_height_above_dsm -f

No clump map given, using MASK
1:0.73:68050:93627:73.31:26.22:0.00
(Mon Jul 26 22:33:19 2021) Command finished (0 sec)

```
The below command in the above output gives some kind of warning, which I
am not able to understand.

`v.surf.rst input=polygon_points zcolumn=height elevation=dsm_below_pile
--overwrite`

And thus at the last, the volume output is 0.00.
Any suggestions or hints, as to what is going wrong?

-- 
Regards,
Ayush Chauhan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20210726/3825b8e0/attachment.html>