Gdal Bug? was: Re: [gdal-dev] JP2MRSID Issues

[Frank Warmerdam]

Stephen Woodbridge wrote:
> Frank,
> 
> Here is what I get from the debug output. I'm a little surprised it is 
> trying to extract from zoom 1 instead of zoom 0. I didn't think I was 
> scaling this but maybe some rounding is causing that.
...
> GDAL: GDALDriver::Create(GTiff,out.tif,6029,6029,3,Byte,0x86d1bc0)
> MrSID: Opened zoom level 1 with size 18005x24724.
> 
> MrSID: Opened zoom level 2 with size 9003x12362.
...
> MrSID: Opened zoom level 0 with size 36010x49447.
> 
> MrSID: Opened image: width 36010, height 49447, bands 4

> MrSID: RasterIO() - using optimized dataset level IO.
> MrSID: Dataset:IRasterIO(25432,42149 5066x6973 -> 5066x6973 -> 
> 5066x6973, zoom=1)
> gdalwarp: ../compressed/compressed.cpp:1724: bool 
> kd_tile::read_tile_part_header(): Assertion `tpart_body_length >= 0' 
> failed.

Steve,

I think the zoom level is a red herring.  I believe the zoom=1 is reporting
the zoom level (1:1) in lizardtech terms, and is not directly related to
the earlier reporting of "zoom level 1" which is the 2:1 down sampled layer.

Looking in the code in gdal/frmts/mrsid/mrsiddataset.cpp near this case I see:

     int sceneWidth  = (int)(nXSize * maxWidth / (double)maxWidthAtL0 + 0.99);
     int sceneHeight = (int)(nYSize * maxHeight / (double)maxHeightAtL0 + 0.99);

In this case I believe there might sometimes be a problem with the calculation
of nYSize * maxHeight being done with 32bit integers.  Could you possibly try
changing these two lines to look like:

     int sceneWidth  =
         (int)((nXSize * (GIntBig)maxWidth ) / (double)maxWidthAtL0  + 0.99);
     int sceneHeight =
         (int)((nYSize * (GIntBit)maxHeight) / (double)maxHeightAtL0 + 0.99);

and see if that helps?   If so, I'll get this into 1.6 and 1.5 as a priority
fix.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent