[GRASS-user] v.vol.rst interpolation results in rectangular isosurfaces

Hi,

Using v.vol.rst, (see command below, and g.region), the interpolation results in rectangular areas in certain areas, see attached photo.
Does this have to do with the segmentation process or something else?

v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn=“db\ |
| l_2” tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\ |
| cale=1.0 zscale=1.0 elevation=“jan25”

(Sat Jan 26 13:37:21 2019) Command finished (0 sec)
(Sat Jan 26 13:37:44 2019)
r3.info map=Jan25@Toronto
±---------------------------------------------------------------------------+
| Layer: Jan25@Toronto Date: Fri Jan 25 22:12:59 2019 |
| Mapset: Toronto Login of Creator: Francois Charti |
| Location: Toronto |
| DataBase: C:\Users\Francois Chartier\Documents\grassdata |
| Title: jan25 |
| Units: none |
| Vertical unit: units |

Timestamp: none
Type of Map: raster_3d Number of Categories: 0
Data Type: FCELL
Rows: 400
Columns: 450
Depths: 65
Total Cells: 11700000
Total size: 27646661 Bytes
Number of tiles: 1575
Mean tile size: 17553 Bytes
Tile size in memory: 32400 Bytes
Number of tiles in x, y and z: 15, 15, 7
Dimension of a tile in x, y, z: 30, 27, 10
Projection: UTM (zone 17)
N: 4837000 S: 4833000 Res: 10
E: 632500 W: 628000 Res: 10
T: 115 B: 50 Res: 1
Range of data: min = -25.42733002 max = 121.86579132
Data Source:
Data Description:
generated by v.vol.rst
Comments:
v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn="db\
l_2" tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\
cale=1.0 zscale=1.0 elevation=“jan25”
±---------------------------------------------------------------------------+
(Sat Jan 26 13:37:45 2019) Command finished (0 sec)

C:\Users\Francois Chartier>g.region -p3
projection: 1 (UTM)
zone: 17
datum: nad83
ellipsoid: grs80
north: 4837000
south: 4833000
west: 628000
east: 632500
top: 115.00000000
bottom: 50.00000000
nsres: 10
nsres3: 10
ewres: 10
ewres3: 10
tbres: 1
rows: 400
rows3: 400
cols: 450
cols3: 450
depths: 65
cells: 180000
cells3: 11700000

C:\Users\Francois Chartier>

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(attachments)

jan26squarevvolrst.jpg

On Sat, Jan 26, 2019 at 7:43 PM Francois Chartier <fra.chartier@gmail.com> wrote:

Hi,

Using v.vol.rst, (see command below, and g.region), the interpolation results in rectangular areas in certain areas, see attached photo.

Does this have to do with the segmentation process or something else?

Most probably yes, try to increase npmin. Maybe you also need to increase segmax, but segmax should not be increased without increasing npmin, otherwise you might get more of these block artefacts.

Markus M

v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn=“db\ |
| l_2” tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\ |
| cale=1.0 zscale=1.0 elevation=“jan25”

(Sat Jan 26 13:37:21 2019) Command finished (0 sec)
(Sat Jan 26 13:37:44 2019)
r3.info map=Jan25@Toronto
±---------------------------------------------------------------------------+
| Layer: Jan25@Toronto Date: Fri Jan 25 22:12:59 2019 |
| Mapset: Toronto Login of Creator: Francois Charti |
| Location: Toronto |
| DataBase: C:\Users\Francois Chartier\Documents\grassdata |
| Title: jan25 |
| Units: none |
| Vertical unit: units |

Timestamp: none
Type of Map: raster_3d Number of Categories: 0
Data Type: FCELL
Rows: 400
Columns: 450
Depths: 65
Total Cells: 11700000
Total size: 27646661 Bytes
Number of tiles: 1575
Mean tile size: 17553 Bytes
Tile size in memory: 32400 Bytes
Number of tiles in x, y and z: 15, 15, 7
Dimension of a tile in x, y, z: 30, 27, 10
Projection: UTM (zone 17)
N: 4837000 S: 4833000 Res: 10
E: 632500 W: 628000 Res: 10
T: 115 B: 50 Res: 1
Range of data: min = -25.42733002 max = 121.86579132
Data Source:
Data Description:
generated by v.vol.rst
Comments:
v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn="db\
l_2" tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\
cale=1.0 zscale=1.0 elevation=“jan25”
±---------------------------------------------------------------------------+
(Sat Jan 26 13:37:45 2019) Command finished (0 sec)

C:\Users\Francois Chartier>g.region -p3
projection: 1 (UTM)
zone: 17
datum: nad83
ellipsoid: grs80
north: 4837000
south: 4833000
west: 628000
east: 632500
top: 115.00000000
bottom: 50.00000000
nsres: 10
nsres3: 10
ewres: 10
ewres3: 10
tbres: 1
rows: 400
rows3: 400
cols: 450
cols3: 450
depths: 65
cells: 180000
cells3: 11700000

C:\Users\Francois Chartier>

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i will do that. i think also as there is denilevation in that area, some of the voxels are above ground which creates these ‘empty’ areas.

On Thu, Jan 31, 2019, 02:25 Markus Metz <markus.metz.giswork@gmail.com wrote:

On Sat, Jan 26, 2019 at 7:43 PM Francois Chartier <fra.chartier@gmail.com> wrote:

Hi,

Using v.vol.rst, (see command below, and g.region), the interpolation results in rectangular areas in certain areas, see attached photo.

Does this have to do with the segmentation process or something else?

Most probably yes, try to increase npmin. Maybe you also need to increase segmax, but segmax should not be increased without increasing npmin, otherwise you might get more of these block artefacts.

Markus M

v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn=“db\ |
| l_2” tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\ |
| cale=1.0 zscale=1.0 elevation=“jan25”

(Sat Jan 26 13:37:21 2019) Command finished (0 sec)
(Sat Jan 26 13:37:44 2019)
r3.info map=Jan25@Toronto
±---------------------------------------------------------------------------+
| Layer: Jan25@Toronto Date: Fri Jan 25 22:12:59 2019 |
| Mapset: Toronto Login of Creator: Francois Charti |
| Location: Toronto |
| DataBase: C:\Users\Francois Chartier\Documents\grassdata |
| Title: jan25 |
| Units: none |
| Vertical unit: units |

Timestamp: none
Type of Map: raster_3d Number of Categories: 0
Data Type: FCELL
Rows: 400
Columns: 450
Depths: 65
Total Cells: 11700000
Total size: 27646661 Bytes
Number of tiles: 1575
Mean tile size: 17553 Bytes
Tile size in memory: 32400 Bytes
Number of tiles in x, y and z: 15, 15, 7
Dimension of a tile in x, y, z: 30, 27, 10
Projection: UTM (zone 17)
N: 4837000 S: 4833000 Res: 10
E: 632500 W: 628000 Res: 10
T: 115 B: 50 Res: 1
Range of data: min = -25.42733002 max = 121.86579132
Data Source:
Data Description:
generated by v.vol.rst
Comments:
v.vol.rst --overwrite input=“Dec16CleanedJjan12@Toronto” wcolumn="db\
l_2" tension=10 smooth=0.1 segmax=50 npmin=200 npmax=700 dmin=0.1 ws\
cale=1.0 zscale=1.0 elevation=“jan25”
±---------------------------------------------------------------------------+
(Sat Jan 26 13:37:45 2019) Command finished (0 sec)

C:\Users\Francois Chartier>g.region -p3
projection: 1 (UTM)
zone: 17
datum: nad83
ellipsoid: grs80
north: 4837000
south: 4833000
west: 628000
east: 632500
top: 115.00000000
bottom: 50.00000000
nsres: 10
nsres3: 10
ewres: 10
ewres3: 10
tbres: 1
rows: 400
rows3: 400
cols: 450
cols3: 450
depths: 65
cells: 180000
cells3: 11700000

C:\Users\Francois Chartier>

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