Hmm, yes that one works for me. I simplified my example for the
email, maybe there's a memory problem, or raster size problem?
I originally tried to resample a GRASS raster DEM directly. It's
really 1000m cell size, 12809x18192 float cells, and want to resample
to 21000m and 7000m. That wasn't working so I exported to Geotiff
(Int16 cells) with r.out.gdal. The exported image has the nulls as
-32768. That doesn't work either.
... ah! memory! I just tried with -wm 250 and I get the nulls. And
the nasty artifacts. I think I want the nulls filled now ;) I saw a
bug about this on the tracker but it was fixed. Maybe this is a
different problem?
On Sep 10, 2009, at 5:56 PM, Even Rouault wrote:
Selon William Kyngesburye <[email protected]>:
I don't manage to reproduce your issue neither with trunk nor with
1.6.2 with a
indem.tif generated by the following python script :
import gdal
import osr
ds = gdal.GetDriverByName('GTiff').Create('indem.tif', 500, 500, 1,
gdal.GDT_Int16)
ds.SetGeoTransform([500000, 10, 0, 45000000, 0, -10])
sr = osr.SpatialReference()
sr.ImportFromEPSG(32631)
ds.SetProjection(sr.ExportToWkt())
ds.GetRasterBand(1).Fill(-32768)
ds.GetRasterBand(1).SetNoDataValue(-32768)
ones = ''
for i in range(50*50):
ones = ones + '\001\000'
ds.GetRasterBand(1).WriteRaster(225,225,50,50, ones, 25, 25)
ds = None
and
gdalwarp -tr 100 100 -ot Int16 -r lanczos -dstnodata -32768
indem.tif outdem.tif
You need to specify -dstnodata -32768. The result I get is as
expected a square
of ones at the middle of nodata values at -32768 (except that due to
a strange
behaviour of lanczos you get some artifacts at the edge of the
square).
Maybe I'm missing something? I'm trying to resample a DEM, with
null/
nodata values in oceans, using gdalwarp. No matter what options I've
used so far, all the resampled nodata areas get filled with 0.
GDAL 1.6.2
So far I've tried (src res 10, nodata -32768 defined in src):
gdalwarp -tr 100 100 -ot Int16 -r lanczos indem.tif outdem.tif
gdalwarp -tr 100 100 -ot Int16 -r lanczos -dstnodata -32768 indem.tif
outdem.tif
gdalwarp -tr 100 100 -ot Int16 -r lanczos -dstalpha indem.tif
outdem.tif
The last time I used gdalwarp, with nulls, was back at 1.5.x, and it
worked then, though I was projecting data (-t_srs), instead of only
resampling. (I'd have to dig up an old 1.5 to see if it still works)
-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/
"I ache, therefore I am. Or in my case - I am, therefore I ache."
- Marvin
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-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/
"History is an illusion caused by the passage of time, and time is an
illusion caused by the passage of history."
- Hitchhiker's Guide to the Galaxy
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