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
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