Hi,
I'm running GRASS through the QGIS (v1.0.5) interface on Windows XP.
The GRASS folder in the QGIS installation says 'grass-6.4.0svn'.
I have a polygon layer with 22 polygons and a raster slope layer. When
I run v.rast.stats with these two layers, two of the polygons have
NULL values in the columns that v.rast.stats adds to the vector layer.
These polygons are not the smallest or on the edges and I've used this
procedure successfully before.
Below are the region, v.info, r.info v.rast.stats outputs. Can anyone
perhaps see why this happens?
g.region -p
projection: 99 (Transverse Mercator)
zone: 0
datum: ** unknown (default: WGS84) **
ellipsoid: wgs84
north: -3122190
south: -3155760
west: -66510
east: -33390
nsres: 90
ewres: 90
rows: 373
cols: 368
cells: 137264
v.info map=subs22_cleaned1@CHI
+----------------------------------------------------------------------------+
| Layer: subs22_cleaned1@CHI
| Mapset: CHI
| Location: c83a_tm_29deg_e
| Database: F:\Hanlie\grassdata
| Title:
| Map scale: 1:1
| Map format: native
| Name of creator: hanlie
| Organization:
| Source date: Wed Nov 17 13:24:57 2010
|----------------------------------------------------------------------------|
| Type of Map: vector (level: 2)
|
| Number of points: 0 Number of areas: 22
| Number of lines: 0 Number of islands: 1
| Number of boundaries: 822 Number of faces: 0
| Number of centroids: 22 Number of kernels: 0
|
| Map is 3D: No
| Number of dblinks: 1
|
| Projection: Transverse Mercator
| N: -3122280 S: -3155670
| E: -33570 W: -66510
|
| Digitization threshold: 0
| Comments:
|
+----------------------------------------------------------------------------+
r.info map=c83a_dem_srtm_90m_slope@PERMANENT
+----------------------------------------------------------------------------+
| Layer: c83a_dem_srtm_90m_slope@PERMA Date: Wed Nov 03 16:21:11 2010
| Mapset: PERMANENT Login of Creator: Administrator
| Location: c83a_tm_29deg_e
| DataBase: F:\Hanlie\grassdata
| Title: percent slope ( c83a_dem_srtm_90m_slope )
| Timestamp: none
|---------------------------------------------------------------------------
|
| Type of Map: raster Number of Categories: 255
| Data Type: FCELL
| Rows: 373
| Columns: 368
| Total Cells: 137264
| Projection: Transverse Mercator
| N: -3122190 S: -3155760 Res: 90
| E: -33390 W: -66510 Res: 90
| Range of data: min = 0.023858 max = 110.669037
|
| Data Source:
| raster elevation file c83a_dem_srtm_90m@PERMANENT
|
|
| Data Description:
| generated by r.slope.aspect
|
| Comments:
| slope map elev = c83a_dem_srtm_90m@PERMANENT
| zfactor = 1.00 format = percent
| min_slp_allowed = 0.000000
|
+----------------------------------------------------------------------------+
v.rast.stats raster=c83a_dem_srtm_90m_slope@PERMANENT
vector=subs22_cleaned1@CHI =area =1 colprefix=slope
Statistics calculated from raster map and uploaded to attribute
table of vector map .
Done.
Successfully finished
Thanks
Hanlie