In GRASS plugin, r.water.outlet is not working

[micha]

I cannot get expected results with the r.water.outlet GRASS module in QGIS 1.3.0. I've tried in a few different locations, on both win and linux setups, and I always get a uniform raster with value 0 covering the whole region. I recall this working properly in earlier versions of QGIS (pre-1.0)

To duplicate the issue: In the North Carolina database, run r.watershed using the elevation raster to create flow direction, streams and catchments rasters. Then run r.water.outlet using the resulting flow direction, and a drainage outlet point on the streams raster. Results are always a black raster covering the whole region.

Working in GRASS, outside of QGIS, using the same GRASS database, flow direction, and same easting-northing values results in a correct drainage basin.

[rblazek]

Works for me (svn trunk) but the output map displayed in qgis with default color map (grayscale) is black.

Are you sure that realy the values are 0, try r.stats -c? Try to change in raster layer options the colormap to pseudo color in qgis.

I believe, that the bug is in qgis in rendering of a layer with values 0 and 1 using grayscale colormap. If you confirm this, please close this ticket as invalid and create a new one for this problem.

[micha]

Quite right! I apologize for mis-reporting. The module r.water.outlet indeed works, but QGIS displays grayscale values of 0 and 1 as all black, so there's no differentiation of the final watershed. Changing the symbology to pseudocolor (or any other color ramp) will show the resulting watershed correctly.