I'm testing r.hazard.flood and noticed that it computes the flood and
mti layers on the full region of the elevation raster instead of the
pre-defined region settings.
The relvant code I found from the r.hazard.flood is this:
# Detect cellsize of the DEM
info_region = grass.read_command('g.region', flags = 'p', rast =
'%s' % (r_elevation))
dict_region = grass.parse_key_val(info_region, ':')
resolution = (float(dict_region['nsres']) + float(dict_region['ewres']))/2
grass.message("Cellsize : %s " % resolution)
Would it be possible to either respect the current region settings or
add a flag to choose between the dem region settings or current region
settings?
--
cheers,
maning
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I'm testing r.hazard.flood and noticed that it computes the flood and
mti layers on the full region of the elevation raster instead of the
pre-defined region settings.
The relvant code I found from the r.hazard.flood is this:
# Detect cellsize of the DEM
info_region = grass.read_command('g.region', flags = 'p',
rast =
'%s' % (r_elevation))
dict_region = grass.parse_key_val(info_region, ':')
resolution = (float(dict_region['nsres']) +
float(dict_region['ewres']))/2
grass.message("Cellsize : %s " % resolution)
Would it be possible to either respect the current region settings or
add a flag to choose between the dem region settings or current region
settings?
if it needs to detect the original raster cell resolution (usually that's only needed to avoid aliasing artifacts in certain situations) it should use r.info to get the answer. I'm guessing due to the averaging of the ew and ns resolutions avoiding aliasing isn't the case.
if a module wants to change the region (and almost none should ever do that except for g.region by itself) it should set up a temporary WIND_OVERRIDE first, in the case of python scripting there is an easy grass python function to make that and clean it up at the end. (otherwise parallel jobs get their regions messed up mid-run, and region changes without you expecting it will)
I suspect grass.raster's raster_info() is the better way for r.hazard.flood to do what it's trying to do now. But also just querying the current g.region info without changing anything is probably even better, as that is what the other raster commands will expect to use. If the user should align perfectly with the input map first, it should be noted in the help page for them to do it manually before running the module.
I’m testing r.hazard.flood and noticed that it computes the flood and
mti layers on the full region of the elevation raster instead of the
pre-defined region settings.
The relvant code I found from the r.hazard.flood is this:
Would it be possible to either respect the current region settings or
add a flag to choose between the dem region settings or current region
settings?
if it needs to detect the original raster cell resolution (usually that’s only needed to avoid aliasing artifacts in certain situations) it should use r.info to get the answer. I’m guessing due to the averaging of the ew and ns resolutions avoiding aliasing isn’t the case.
if a module wants to change the region (and almost none should ever do that except for g.region by itself) it should set up a temporary WIND_OVERRIDE first, in the case of python scripting there is an easy grass python function to make that and clean it up at the end. (otherwise parallel jobs get their regions messed up mid-run, and region changes without you expecting it will)
I suspect grass.raster’s raster_info() is the better way for r.hazard.flood to do what it’s trying to do now. But also just querying the current g.region info without changing anything is probably even better, as that is what the other raster commands will expect to use. If the user should align perfectly with the input map first, it should be noted in the help page for them to do it manually before running the module.
Thanks for suggestion, applied in r59879
Cheers,
madi
–
Best regards,
Dr. Margherita DI LEO
Scientific / technical project officer
European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261
Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission.