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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.<br>
<br>
Robb<br>
<br>
On 11/29/2011 12:58 AM, Chaitanya kumar CH wrote:
<blockquote
cite="mid:CAMKgpObPr98HPFaXOC4yP22R9K2C5Crwiq3xfWhgDp5pJQLy6Q@mail.gmail.com"
type="cite">Robb,<br>
<br>
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.<br>
<br>
[1]: <a moz-do-not-send="true"
href="http://www.gdal.org/gdaladdo.html">http://www.gdal.org/gdaladdo.html</a><br>
<br>
<div class="gmail_quote">On Mon, Nov 28, 2011 at 11:53 PM, Robb
Wright <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:robbkwright@gmail.com">robbkwright@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<br>
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:<br>
gdaladdo.exe --config COMPRESS_OVERVIEW DEFLATE -r average<br>
<br>
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.<br>
<br>
Does anybody know of the availability of the Lanczos
resampling method for gdaladdo - or of another way to create
.ovr files with Lanczos?<br>
<br>
Robb<br>
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</blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
Best regards,<br>
Chaitanya kumar CH.<br>
<br>
+91-9494447584<br>
17.2416N 80.1426E<br>
</blockquote>
<br>
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