[gdal-dev] gdalwarp fills nulls?

[Greg Coats]

The GDAL default value for GDAL_CACHEMAX is 40 MB. I routinely set up  
my gdal_translate scripts to run with a larger value for GDAL_CACHEMAX.
	export GDAL_CACHEMAX_value=50
	gdal_translate --config GDAL_CACHEMAX ${GDAL_CACHEMAX_value}
In my benchmark tests, I have observed that this small increase in  
GDAL_CACHEMAX has dramatically reduced processing time by a factor of  
more than 60, from 10473 to 166 seconds.

I do not see any information about a -wm option on these web pages
	http://www.gdal.org/gdal_utilities.html
	http://www.gdal.org/gdal_translate.html
I would appreciate information about the -wm option. What is the  
default value? Are the units MB of memory?
Greg

On Sep 11, 2009, at 11:42 AM, William Kyngesburye wrote:

> 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 <woklist at kyngchaos.com>:
>>
>> 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
>>>
>>>
>>> _______________________________________________
>>> gdal-dev mailing list
>>> gdal-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>>
>>
>>
>
> -----
> 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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