[gdal-dev] .ovr files and Lanczos

[Eli Adam]

Are .ovr files just tifs with a different file extension?

If so, could you use, gdalwarp -tr # # -r lanczos output.ovr?

Eli

On Mon, Nov 28, 2011 at 10:57 PM, Chaitanya kumar CH
<chaitanya.ch at gmail.com> wrote:
> Robb,
>
> Note that the quality is effected by the levels you choose.
> Can you provide a small part of the image where the overview is garbled the
> most.
>
>
> On Tue, Nov 29, 2011 at 12:00 PM, Robb Wright <robbkwright at gmail.com> wrote:
>>
>> 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.
>>
>> Robb
>>
>>
>> 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>
>> 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
>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>>
>>
>>
>> --
>> Best regards,
>> Chaitanya kumar CH.
>>
>> +91-9494447584
>> 17.2416N 80.1426E
>>
>>
>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
>
> +91-9494447584
> 17.2416N 80.1426E
>
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