[Gdal-dev] Windows CE - GDALDatasetRasterIO error

[jetelus at centrum.cz]

_____________________________________________________________
> Od: jetelus at centrum.cz
> Komu: <gdal-dev at lists.maptools.org>
> Datum: 05.11.2007 14:22
> Předmět: Re: [Gdal-dev] Windows CE - GDALDatasetRasterIO error
>
>>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.
>>>
>>> _______________________________________________
>>> 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
>>
>
>Hi,
>thx for testing the image. I tryed to zoom to very small areas and it works.
>So I added check for free memory before and after GDALDatasetRasterIO call
>and discovered there is 11 MB difference. This is probably reason why all
>following operations with larger areas are out of memory.
>
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Finally I solved it! I was hunting that lost memory and I
discovered there is cache system implemented in GDAL :-)
Problem is it's default size - 40 MB - too much for CE.
I set it to 4 MB using GDALSetCacheMax() and all errors are
gone - lol I suck I know :) but it would be nice to add some
note to GDALDatasetRasterIO documentation - something like
there is cache system which memory usage can be controlled.
I can display even 5 MB JPEGs now on CE! Have a nice day!

to Tom: There are no overviews in that image. BTW how are you
doing with that CCITTFax? I am interested in it too :)