[Gdal-dev] Windows CE - GDALDatasetRasterIO error

[Tom Kazimiers]

jetelus at centrum.cz schrieb:
>> 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
>>
>>     
>
> Yes, I can load and display image. I get this error only when zooming.
> (and no errors at all for 4bpp version)
>
> I have this code:
> (Windows Mobile 2003 Second Edition)
>
>  --------------------------------------------------------------------------------
>  ...
>  int panBandMap[1];
>  panBandMap[0] = 1;
>
>  unsigned char* pData = (unsigned char*) malloc(nBufXSize * nBufYSize);
>
>  if (!pData)
>  {
> 	CString msg("Not enough memory.");
> 	TRACE(msg);
> 	MessageBox(NULL,msg,NULL,0);
> 	return false;
>  }
>
>  CPLErr e=GDALDatasetRasterIO(HDataset, GF_Read, nXOff, nYOff, nXSize, nYSize,
>         pData, nBufXSize, nBufYSize, GDT_Byte, 1, panBandMap, 1, nBufXSize, 1);
>
>  if (e != CE_None)
>  {
>         free(pData);
> 	CString msg(CPLGetLastErrorMsg());
> 	TRACE(msg);
> 	MessageBox(NULL,msg,NULL,0);
>         return false;
>  }
>  ...
>  show loaded raster
>  ...
>  free(pData);
>  --------------------------------------------------------------------------------
>
> works for whole image:
>
> nXOff = 0
> nYOff = 0
> nXSize = 11953
> nYSize = 10268
> nBufXSize = 224
> nBufYSize = 192
>
> gives "Out of memory allocating 59765 byte raster cache block." for
> raster part (same for similar areas when zooming):
>
> nXOff = 3011
> nYOff = 1571
> nXSize = 7115
> nYSize = 6561
> nBufXSize = 248
> nBufYSize = 228
>
> Image is here (450kB):
>
> http://rapidshare.com/files/67552472/tif_lzw.rar.html
>
> Thx for your time.
>
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> Gdal-dev mailing list
> Gdal-dev at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/gdal-dev
>
>   
Hi,

I tryed your image out with my code and was surprised that my code can
handle that large images ;) - so just a question: Are there overviews in
the image?

With my code I was able to pan and zoom around - but after about 8
actions (I do not know exactly what the problem is - well, I will look
after it) I get the same error with the same amount of memory:
Return: 3
Last Error: Out of memory allocating 59765 byte raster cache block./

This error occured one time after I zoomed in (with about factor 2) and
another time when I zoomed out (about factor 0.4) -but not all the time.
I was also abtle to zoom deep in and out.
With only panning I get this error not that fast I think.

I don't know if this helps- but I try to test some more tonight.

Bye,
Tom