[gdal-dev] .ovr files and Lanczos

Robb Wright robbkwright at gmail.com
Tue Nov 29 01:30:29 EST 2011

Thanks Chaitanya.  Unfortunately gdaladdo doesn't support the Lanczos 
resampling type.  Lanczos creates - by far - the best looking 
downsampled images for my type of rasters.  What I'm looking for is a 
way to create pyramid layers/.ovr files using the Lanczos resampling method.


On 11/29/2011 12:58 AM, Chaitanya kumar CH wrote:
> Robb,
> If you are using gdal version 1.6 or later, you can use the -ro 
> option[1]. It opens the tiff file in read-only mode and creates 
> external overview.
> [1]: http://www.gdal.org/gdaladdo.html
> On Mon, Nov 28, 2011 at 11:53 PM, Robb Wright <robbkwright at gmail.com 
> <mailto:robbkwright at gmail.com>> wrote:
>     I'm working with indexed color types of raster data (charts).  The
>     data is in RGB geotiffs and I'm using gdaladdo to create pyramid
>     layers for them.  Unfortunately, the best method for this raster
>     type available using gdaladdo is still pretty bad - much of the
>     linework becomes garbled when viewing the pyramids.  The
>     best-looking method that I've been able to come up with is:
>     gdaladdo.exe --config COMPRESS_OVERVIEW DEFLATE -r average
>     The Lanczos algorithm method works beautifully when used with
>     other programs - but I need to create .ovr files.  gdal_retile.py
>     output looks great - but I can't figure out how to create .ovr
>     files from that output.
>     Does anybody know of the availability of the Lanczos resampling
>     method for gdaladdo - or of another way to create .ovr files with
>     Lanczos?
>     Robb
>     _______________________________________________
>     gdal-dev mailing list
>     gdal-dev at lists.osgeo.org <mailto:gdal-dev at lists.osgeo.org>
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> -- 
> Best regards,
> Chaitanya kumar CH.
> +91-9494447584
> 17.2416N 80.1426E

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