[Gdal-dev] Windows CE - GDALDatasetRasterIO error

[Mateusz Loskot]

jetelus at centrum.cz wrote:
>>> Hi, I open and display raster without problems but when I
>>> try zooming I get CE_Failure from GDALDatasetRasterIO with
>>> this error message using GDAL 1.4.2:
>>>
>>> "Assertion `nLockCount == 0' failed in file `..\..\..\gcore
>>> \gdalrasterblock.cpp', line 219"
>>> (and app crashs)
>>>
>>> and this error message using GDAL 1.4.3:
>>>
>>> "Out of memory allocating 59765 byte raster cache block."
>>> (its little better becasuse app doesnt crash)
>>>
>>> RASTER INFO:
>>> bpp: 1
>>> compression: LZW
>>> resolution: 11953 x 10268.
>>> file size: 658kB
>>>
>>> When I convert this raster to 4 bits per pixel everything
>>> is ok and I get no errors but raster file size grows to
>>> 1.7MB. Any ideas? Thx.
>>
>>I don't know what device you have but you're trying to open ~120 MB
>>raster in one shot, on mobile device.
>>The error message is clear to me, you're dealing without of memory issue.
>>
>>IMHO, it's not a good idea to feed mobile device with images of that
>>big. Better tile them into smaller pieces, use zoom levels, etc.
>>GDAL for Windows CE gives you with tools to solve this problem.
>>
>>Keep in mind that "GDAL for Windows CE" does not mean you can use all
>>GDAL features on a mobile device the same way as on normal workstation.
>>There are obvious hardware limitations you can not overcome.
>>
>>Cheers
>>--
>>Mateusz Loskot
>>http://mateusz.loskot.net
>>
>
> Thank you, I understand but why it works with 4 bpp version of same raster
> which is even bigger?

You wrote that you don't get any errors, but does it mean you can load it
and display?

Perhaps there is a bug, we can not exclude this option :-)
If you want, you can send me your image file and piece of code presenting
what are you doing exactly, then I will be able to investigate the problem.

Cheers
-- 
Mateusz Loskot
http://mateusz.loskot.net