I only have the app running on an internal server at the moment. I will try to make a few WMS requests to generate images and will post the resulting output on an external box for you. My GSD is 18", but I am probably going to increase that to 36" for the final product.<br>
<br>Thanks.<br>--<br><br><div class="gmail_quote">On Fri, May 2, 2008 at 2:05 PM, Martin Chapman <<a href="mailto:mchapman@texelinc.com">mchapman@texelinc.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p><span style="font-size: 11pt; color: rgb(31, 73, 125);">Can you let me download the image you are having issues with?
You want to have a pyramid of files that are varying levels. Ideally they
should be a factor of 2, i.e… 2, 4, 8, 16, 32 , 64, 128, 256, 512, 1024, 2048,
4096, … . What is the gsd of your base image?</span></p>
<p><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p><span style="font-size: 10.5pt; font-family: Consolas; color: rgb(31, 73, 125);">Martin</span></p>
<p><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div style="border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; border-width: 1pt medium medium; padding: 3pt 0in 0in;">
<p><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> Roger André
[mailto:<a href="mailto:randre@gmail.com" target="_blank">randre@gmail.com</a>] <br>
<b>Sent:</b> Friday, May 02, 2008 2:54 PM<br>
<b>To:</b> <a href="mailto:mchapman@texelinc.com" target="_blank">mchapman@texelinc.com</a><br>
<b>Cc:</b> <a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>; <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [gdal-dev] What options for display of high-quality ortho's
via WMS?</span></p>
</div><div><div></div><div class="Wj3C7c">
<p> </p>
<p style="margin-bottom: 12pt;">Well, generating overviews of
the 8-bit data produced pretty awful looking results. gdaladdo did warn
me, so I can't blame it. ;) Also changing the resampling to
bilinear did not improve the matter.<br>
<br>
Is it better to create large, single-image overviews, or to create many tiles
of varying resolution levels?<br>
--<br>
<br>
<br>
</p>
<div>
<p>On Thu, May 1, 2008 at 11:37 PM, <<a href="mailto:mchapman@texelinc.com" target="_blank">mchapman@texelinc.com</a>> wrote:</p>
<p>Maybe try generating an overview<br>
(.ovr) file for the image. Perhaps the resampling will be better. Also see if
you can specify in mapserver the resampling method to cubic convolution or
something other than nearest neighbor.<br>
<br>
Martin<br>
<br>
<br>
Sent via BlackBerry by AT&T</p>
<div>
<div>
<p><br>
-----Original Message-----<br>
From: "Roger André" <<a href="mailto:randre@gmail.com" target="_blank">randre@gmail.com</a>><br>
<br>
Date: Thu, 1 May 2008 21:20:04<br>
<a href="mailto:To%3Agdal-dev@lists.osgeo.org" target="_blank">To:gdal-dev@lists.osgeo.org</a><br>
Subject: [gdal-dev] What options for display of high-quality ortho's via WMS?<br>
<br>
<br>
Throwing out a general question to this list because I know that many of us use
a variety of different applications to "get the job done", but use the
GDAL tools as the common unifier (at least I like to think so). I'm
putting together a Mapserver-driven web map that uses OpenLayers to get data
via WMS. It's all working quite nicely, except for my aerial photo layer,
which I am not incredibly pleased with. Despite using every tweak I could
find (convert from RGB to 8-bit with pct2rgb.py, use OUTPUTFORMAT with
GD/PNG, and use "DITHER=YES" in mapfile, I cannot get a very
high quality rendition of the photo layer in my WMS output. It looks
grainy in areas with solid color and generally a bit "pixelly".
So I have a couple of questions.<br>
<br>
1. Is some loss of image quality an unavoidable side-effect of using
Mapserver?<br>
<br>
2. If not 1, then are there other tweaks that can be done to further improve
the quality of my output? (Note that I intend to use Tilecache, so maybe
slow initial performance may is an acceptable trade off, I dunno.)<br>
<br>
3. If yes to 1, then what other open source tools do a better job of rendering
photo data? (I intend to test some of the data in GeoServer, but I
haven't done so yet.)<br>
<br>
Thanks in advance for your feedback.<br>
<br>
Roger</p>
</div>
</div>
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<p> </p>
</div></div></div>
</div>
</blockquote></div><br>