[GRASS-dev] r.slope.aspect with -n flag giving aspect of flat areas as -9998
Pedro Venâncio
pedrongvenancio at gmail.com
Tue Jan 28 03:49:12 PST 2020
Hi all,
I was testing r.slope.aspect with the "new" -n flag, also to include -e and
-n flags in QGIS Processing, but -n flag is giving aspect values of flat
areas as -9998, instead of -9999, when the precision choosed is CELL, and
the output data type is CELL.
https://grass.osgeo.org/grass78/manuals/r.slope.aspect.html
I've tested with GRASS 7.6 (on Linux) and GRASS 7.8.2 (on Windows), both in
the GUI and CLI.
(Tue Jan 28 11:19:40 2020)
r.slope.aspect -e -n --verbose elevation=SRTM_PT_25m PERMANENT
slope=SRTM_PT_25m_Slope_Deg_GRASS aspect=SRTM_PT_25m_Aspect_Std_GRASS
precision=CELL
Percent complete...
Elevation products for mapset <PERMANENT> in <SRTM_PT_25m>
Min computed aspect 0.0000, max computed aspect 360.0000
Aspect raster map <SRTM_PT_25m_Aspect_Std_GRASS> complete
Min computed slope 0.0000, max computed slope 75.2970
Slope raster map <SRTM_PT_25m_Slope_Deg_GRASS> complete
(Tue Jan 28 11:20:24 2020) Comando terminado (43 sec)
r.info map=SRTM_PT_25m_Aspect_Std_GRASS PERMANENT
+----------------------------------------------------------------------------+
| Map: SRTM_PT_25m_Aspect_Std_GRASS@ Date: Tue Jan 28 11:20:24 2020
|
| Mapset: PERMANENT Login of Creator: PedroVenancio
|
| Location: SRTM_PT_25m
|
| DataBase: D:\ICNF\Modelos_Combustivel_2018\Landscape_File\grass78
|
| Title: Aspect counterclockwise in degrees from east
|
| Timestamp: none
|
|----------------------------------------------------------------------------|
|
|
| Type of Map: raster Number of Categories: 360
|
| Data Type: CELL
|
| Rows: 23200
|
| Columns: 11360
|
| Total Cells: 263552000
|
| Projection: ETRS89 / Portugal TM06
|
| N: 278000 S: -302000 Res: 25
|
| E: 164000 W: -120000 Res: 25
|
| Range of data: min = -9998 max = 360
|
|
|
| Data Source:
|
| raster elevation file SRTM_PT_25m PERMANENT
|
|
|
|
|
| Data Description:
|
| generated by r.slope.aspect
|
|
|
| Comments:
|
| aspect map elev = SRTM_PT_25m PERMANENT
|
| zfactor = 1.00
|
| min_slope = 0.000000
|
|
|
| r.slope.aspect --verbose -e -n elevation="SRTM_PT_25m PERMANENT" slo\
|
| pe="SRTM_PT_25m_Slope_Deg_GRASS" aspect="SRTM_PT_25m_Aspect_Std_GRAS\
|
| S" format="degrees" precision="CELL" zscale=1.0 min_slope=0.0
|
|
|
+----------------------------------------------------------------------------+
(Tue Jan 28 11:26:09 2020) Comando terminado (0 sec)
Using the default precision as FCELL, all goes ok:
(Tue Jan 28 11:33:08 2020)
r.slope.aspect -e -n --verbose elevation=SRTM_PT_25m PERMANENT
slope=SRTM_PT_25m_Slope_Deg_GRASS_2 aspect=SRTM_PT_25m_Aspect_Std_GRASS_2
Percent complete...
Elevation products for mapset <PERMANENT> in <SRTM_PT_25m>
Min computed aspect 0.0000, max computed aspect 359.8096
Aspect raster map <SRTM_PT_25m_Aspect_Std_GRASS_2> complete
Min computed slope 0.0000, max computed slope 75.2970
Slope raster map <SRTM_PT_25m_Slope_Deg_GRASS_2> complete
(Tue Jan 28 11:34:01 2020) Comando terminado (53 sec)
(Tue Jan 28 11:34:27 2020)
r.info map=SRTM_PT_25m_Aspect_Std_GRASS_2 PERMANENT
+----------------------------------------------------------------------------+
| Map: SRTM_PT_25m_Aspect_Std_GRASS_ Date: Tue Jan 28 11:34:01 2020
|
| Mapset: PERMANENT Login of Creator: PedroVenancio
|
| Location: SRTM_PT_25m
|
| DataBase: D:\ICNF\Modelos_Combustivel_2018\Landscape_File\grass78
|
| Title: Aspect counterclockwise in degrees from east
|
| Timestamp: none
|
|----------------------------------------------------------------------------|
|
|
| Type of Map: raster Number of Categories: 360
|
| Data Type: FCELL
|
| Rows: 23200
|
| Columns: 11360
|
| Total Cells: 263552000
|
| Projection: ETRS89 / Portugal TM06
|
| N: 278000 S: -302000 Res: 25
|
| E: 164000 W: -120000 Res: 25
|
| Range of data: min = -9999 max = 359.8097
|
|
|
| Data Source:
|
| raster elevation file SRTM_PT_25m PERMANENT
|
|
|
|
|
| Data Description:
|
| generated by r.slope.aspect
|
|
|
| Comments:
|
| aspect map elev = SRTM_PT_25m PERMANENT
|
| zfactor = 1.00
|
| min_slope = 0.000000
|
|
|
| r.slope.aspect --verbose -e -n elevation="SRTM_PT_25m PERMANENT" slo\
|
| pe="SRTM_PT_25m_Slope_Deg_GRASS_2" aspect="SRTM_PT_25m_Aspect_Std_GR\
|
| ASS_2" format="degrees" precision="FCELL" zscale=1.0 min_slope=0.0
|
|
|
+----------------------------------------------------------------------------+
(Tue Jan 28 11:34:28 2020) Comando terminado (0 sec)
The elevation map I'm using is this one:
https://www.fc.up.pt/pessoas/jagoncal/srtm/SRTM_PT_25m.tif
As CELL is a 32 bit integer with a range from -2,147,483,647 to
+2,147,483,647, -9999 should be fine to conform inside it.
Another issue I see is in r.info, that is showing the title as
| Title: Aspect counterclockwise in degrees from east
which is not correct in this case, as the -n flag was used.
Could these be bugs?
Thank you very much.
Best regards,
Pedro Venâncio
-------------- próxima parte ----------
Um anexo em HTML foi limpo...
URL: <http://lists.osgeo.org/pipermail/grass-dev/attachments/20200128/391678d1/attachment-0001.html>
More information about the grass-dev
mailing list