[gdal-dev] How detect the BlockSize to make tiles of my dataset to open it?

[Frank Warmerdam]

On 11-04-20 11:32 AM, Francisco José Reyes Peralta wrote:
> Dear friends,
>
> Using gdalinfo and my dataset i obtain the following data:
>
> *Size: 35000, 20000*
>
> *Pixel Size: 0.5, -0.5*
>
> *Band 1 Block = 35000x1 Type=Byte, ColorInterp=Red*
>
> *Overviews: 17500x10000, 8750x5000, 4375x2500, 2187x1250, 1093x625, 546x312,
> 273x156*
>
> *Band 2 Block = 35000x1 Type=Byte, ColorInterp=Green*
>
> *Overviews: 17500x10000, 8750x5000, 4375x2500, 2187x1250, 1093x625, 546x312,
> 273x156*
>
> *Band 3 Block = 35000x1 Type=Byte, ColorInterp=Blue*
>
> *Overviews: 17500x10000, 8750x5000, 4375x2500, 2187x1250, 1093x625, 546x312,
> 273x156*
>
>
> How can I recognize my optimal blocksize to open a 250 MB ecw file in TILES
> mode because if I read all the dataset I obtain an outofmemory exception.

Francisco,

I believe you will get the best performance reading it one scanline at a time
with all bands at once.  There is a special optimized case in the driver for
this.  But you would need to use the GDALDataset::RasterIO() method to read
all three bands at once instead of reading them each separately.

Best regards,
-- 
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