[GRASS-user] Importing DMSP-OLS in an Lat-Lon based Location

GRASS GRASS user
1

Hi users.

What is exactly wrong when importing imagery from <http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html&gt; in a GRASS LL-based Location?

gdalinfo for one image reports:

Upper Left (-180.0041667, 75.0041667) (180d 0'15.00"W, 75d 0'15.00"N)
Lower Left (-180.0041667, -65.0041661) (180d 0'15.00"W, 65d 0'15.00"S)
Upper Right ( 180.0041652, 75.0041667) (180d 0'14.99"E, 75d 0'15.00"N)
Lower Right ( 180.0041652, -65.0041661) (180d 0'14.99"E, 65d 0'15.00"S)
Center ( -0.0000007, 5.0000003) ( 0d 0' 0.00"W, 5d 0' 0.00"N)

while the created Location, based on this image reports:

n=75.0041666666667
s=-65.0041661066667
w=179.995833333333
e=180.004165226667
nsres=0.00833333330000198
ewres=1.92863436804174e-07
rows=16801
cols=43201
cells=725820001

I can't draw any maps. Is this related/similar to the problem solved for ETOPO1 here: <http://grasswiki.osgeo.org/wiki/Global_datasets#ETOPO1_.28DEM.29&gt;?

Thanks, Nikos

--
Nikos

2

Nikos Alexandris:

What is exactly wrong when importing imagery from
<http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html&gt; in a GRASS
LL-based Location?

gdalinfo for one image reports:
Upper Left (-180.0041667, 75.0041667) (180d 0'15.00"W, 75d 0'15.00"N)
Lower Left (-180.0041667, -65.0041661) (180d 0'15.00"W, 65d 0'15.00"S)
Upper Right ( 180.0041652, 75.0041667) (180d 0'14.99"E, 75d 0'15.00"N)
Lower Right ( 180.0041652, -65.0041661) (180d 0'14.99"E, 65d 0'15.00"S)
Center ( -0.0000007, 5.0000003) ( 0d 0' 0.00"W, 5d 0' 0.00"N)

while the created Location, based on this image reports:
n=75.0041666666667
s=-65.0041661066667
w=179.995833333333
e=180.004165226667
nsres=0.00833333330000198
ewres=1.92863436804174e-07
rows=16801
cols=43201
cells=725820001

I can't draw any maps. Is this related/similar to the problem solved
for ETOPO1 here:
<http://grasswiki.osgeo.org/wiki/Global_datasets#ETOPO1_.28DEM.29&gt;?

I forgot, importing with the "-l" flag, gives a warning:

WARNING: Map bounds have been constrained to geographic coordinates. You
          will almost certainly want to check map bounds and resolution with
          r.info and reset them with r.region before going any further.

So, these need to be re-set?

Nikos

3

Nikos Alexandris:

What is exactly wrong when importing imagery from
<http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html&gt; in a GRASS
LL-based Location?

gdalinfo for one image reports:
Upper Left (-180.0041667, 75.0041667) (180d 0'15.00"W, 75d 0'15.00"N)
Lower Left (-180.0041667, -65.0041661) (180d 0'15.00"W, 65d 0'15.00"S)
Upper Right ( 180.0041652, 75.0041667) (180d 0'14.99"E, 75d 0'15.00"N)
Lower Right ( 180.0041652, -65.0041661) (180d 0'14.99"E, 65d 0'15.00"S)
Center ( -0.0000007, 5.0000003) ( 0d 0' 0.00"W, 5d 0' 0.00"N)

Even Rouault:

The issue is that your image extends a bit beyond the dateline meridian at the
west and at the east, which cause coordinate wrap-up.
You could probably pre-process the image with gdalwarp/gdal_translate with
something like:
gdalwarp in.tif out.tif -te -180 -65.0041661 180 75.0041667

[..]

That seems to be enough. Thank you so much Even. Nikos