[Gdal-dev] problem about "RasterI O"

[qq]

Hi Warmerdam:
 
    The first file I tried to read is a .tif about 70M. Another file is a  .img
file about 10M. Both those two files can be opend by ArcGIS software. But I failed to read them by GDAL. Are the parameters which i set in RasterIO wrong ?
  
Best regards.
 
 
 
 
 
 
 
 



-----ԭʼÓʼþ-----
·¢¼þÈË:"Frank Warmerdam" 
·¢ËÍʱ¼ä:2006-10-10 01:17:59
ÊÕ¼þÈË:"qq" 
³­ËÍ:gdal-dev at lists.maptools.org
Ö÷Ìâ:Re: [Gdal-dev] problem about "RasterIO"


qq wrote:
> HI:
>  
>   I tried to read a .tif file with data type of "GDT_Byte" using the 
> method of "RasterIO". It did well without problem. But When I tied to 
> read a .tif file with data type of "GDT_Int32", it did't work.  My code 
> is here:
>  
> if (RasterBand->GetRasterDataType() == GDT_Int32){
>   LONG* pData;
>   pData = (LONG*) CPLMalloc(sizeof(LONG)*nXSize*nYSize);
>   RasterBand->RasterIO( GF_Read, 0, 0, nXSize, nYSize, pData, nXSize, 
> nYSize,   GDT_Int32, 0, 0 );  
>   }
>  
> The pData is NULL. And the image data can't be read from the file. Would 
> anyone tell what is the wrong? Thanks !

QQ,

It sounds like the buffer allocation is failing because of a lack
of memory.  Is your file large?

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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