[Gdal-dev] MrSID, ECW formats unusable when RasterIO is used - GDAL 1.3.1

[Sergey Malgin]

All,

 

I just finished writing a simple test app that uses GDAL 1.3.1 . My OS is
WinXP. 

 

I use this method:

 

CPLErr GDALRasterBand::RasterIO (
<http://www.gdal.org/gdal_8h.html#4844f11ca9da952f36f3c979b6b0d320>
GDALRWFlag  eRWFlag, int  nXOff, int  nYOff, int  nXSize, int  nYSize, void
*  pData, int  nBufXSize, int  nBufYSize,
<http://www.gdal.org/gdal_8h.html#0287768ebb5ec0ce09259acdb570eb8e>
GDALDataType  eBufType, int  nPixelSpace, int  nLineSpace ) 

 

to render and resample RGB data. It mostly works, but it's quite unusable
when I use MrSID and ECW

 

1. MrSID problem

 

It looks like RasterIO method doesn't use MrSID multiresolution support. It
takes 80 seconds to get data from 3.5MB SID file. I am trying to get full
extent with output dimensions set to approx. 500x500 pixels.

 

 

 

2. ECW problem. 

 

I have 2.5GB ECW. It shows full extent very fast, but when I zoom in a
little, I get back blank image! If I continue to zoom in, eventually I get
the data from lowest pyramid level. 

 

 

 

Please help.

 

 

Sergey Malgin

ESRI, Inc

 

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