[Chameleon] How to specify 24bit output for a WMS layer within an
xml context file?
Jennifer Zeisloft
jzeisloft at gmail.com
Tue Jan 24 11:54:40 EST 2006
Hi Jeff,
Thanks for the tip - that worked!!
Jennifer
On 1/24/06, Jeff McKenna <jmckenna at dmsolutions.ca> wrote:
>
> Have you tried setting Chameleon's "image_type" parameter to PNG24 in
> /config/chameleon.xml?
>
> jeff
>
>
>
> Jennifer Zeisloft wrote:
> > Hello All,
> >
> > I have been having problems displaying raster imagery from web mapping
> > services in MapServer/Chameleon (poor visual resolution, essentially).
> > I first sought help from the MapServer list (pasted below), but have
> > discovered that I likely need Chameleon help.
> >
> > Specifically, I am wondering how I can specify that 24bit output be
> > generated from a layer in a web mapping context.
> >
> > In addition to the responses below, Frank Warmerdam also suggested
> > adding PROCESSING "DITHER=YES" to the mapfile if I do not specify jpeg
> > or png24 in the mapfile output. This did help somewhat. But again, the
> > problem is that I cannot refer to a mapfile in an xml context file (as
> > far as I know). So, there must be some other means in Chameleon of
> > specifying that the output is 24bit rather than 8bit.
> >
> > I am grateful for any hints or ideas you can offer!
> >
> > Thanks!
> >
> > Jennifer Zeisloft
> > UW Sea Grant
> >
> >
> ------------------------------------------------------------------------------------------------------------------
> > >From the MapServer List Discussion:
> >
> > Greetings All,
> >
> > We have been noticing that some (but not all) WMS raster images look
> > pretty terrible (extremely low resolution compared to what they should
> > be) when added to our MapServer application. For instance, from
> > TerraServer (http://terraservice.net/ogcmap.ashx), USGS Digital Ortho
> > Quads are virtually useless regardless of scale, while USGS DRGs look
> > decent. Daily MODIS imagery from NASA JPL World Map Service
> > (http://wms.jpl.nasa.gov/wms.cgi?) has also typically been a problem.
> > And there are others...
> >
> > I have recently been playing with GDAL to display our own rasters, but
> > also partially with the hope that it might somehow magically fix this
> > problem (of course it hasn't).
> >
> > I am wondering whether the display problem is local or if it is on the
> > data custodian's end, and whether this is typically the case. Is there
> > any way to correct it? If it is at the custodial end, what might be
> > done differently to increase the display resolution for WMS clients (so
> > that we don't make the same mistake)?
> >
> > I really appreciate any hints or ideas you can offer.
> >
> > Thanks much!
> >
> > Jennifer Zeisloft
> > UW Sea Grant
> >
> > ------------------------
> > Jennifer -
> >
> > You don't give us much information to go on, other than your dislike of
> > the results!
> >
> > If you're consistently seeing poor-quality results, then there may well
> > be something systematic you're doing in your map files or MapServer
> > configuration. I'm assuming you're using MapServer to generate these
> > "horrible-looking" images. If you are, for example, requesting
> > low-color output from high-color images, you're going to see blotchy
> > output. DRGs are low-color images (only 13 unique colors) so they are
> > not as prone to being affected by a low-color output request.
> >
> > Could you provide an example of the map file and configuration you're
> > using to retrieve and display these images? There's nothing special
> > about the WMS interface that inherently limits image quality - you can
> > get a perfect reproduction of the source imagery in many cases.
> >
> > - Ed
> >
> > Ed McNierney
> > President and Chief Mapmaker
> > TopoZone.com / Maps a la carte, Inc.
> > 73 Princeton Street, Suite 305
> > North Chelmsford, MA 01863
> > Phone: +1 (978) 251-4242
> > Fax: +1 (978) 251-1396
> > ed at topozone.com <mailto:ed at topozone.com>
> >
> > --------------------------------------
> > Thank you for responding, Ed.
> >
> > Actually, these raster data sets are displayed as part of Chameleon
> > contexts (so there is no mapfile). I added the USGS orthos to a mapfile
> > to see if the result was any different and it wasn't (the mapfile code
> > for this layer is pasted below in any case).
> >
> > The application can be found at
> > http://maps.aqua.wisc.edu/lscmp/viewmaps.phtml. The example data sets I
> > am referring to can be found in the Wisconsin: Imagery context.
> >
> > I have read through the documentation on rasters in MapServer, as well
> > as searched list archives and have not been able to determine how I
> > would go about specifying low or high -color output. So, perhaps this
> > is part of the problem?
> >
> > Again, any suggestions are greatly appreciated!!
> >
> > Jennifer Zeisloft
> >
> > LAYER
> > NAME DOQ
> > STATUS ON
> > CONNECTIONTYPE WMS
> > TYPE RASTER
> > CONNECTION "http://terraservice.net/ogcmap.ashx"
> > PROJECTION
> > "init=epsg:4326"
> > END # Projection
> > METADATA
> > "wms_srs" "EPSG:4326"
> > "wms_name" "DOQ"
> > "wms_title" "USGS Digital Ortho-Quadrangles"
> > "wms_onlineresource" "http://terraservice.net/ogcmap.ashx"
> > "wms_abstract" "NA - test"
> > "wms_keywordlist" "NA -test"
> > "wms_server_version" "1.1.1"
> > "wms_formatlist" "image/png,image/jpeg,image/wbmp"
> > "wms_format" "image/png"
> > END # Metadata
> > END # layer
> >
> > -------------------------------------
> > From: Frank Warmerdam <warmerdam at pobox.com
> > <mailto:warmerdam at pobox.com>> Mailed-By: lists.umn.edu
> > <http://lists.umn.edu>
> > Reply-To: Frank Warmerdam <warmerdam at pobox.com <mailto:
> warmerdam at pobox.com>>
> > To: MAPSERVER-USERS at lists.umn.edu <mailto:MAPSERVER-USERS at lists.umn.edu>
> > Date: Jan 23, 2006 10:57 PM
> > Subject: Re: [UMN_MAPSERVER-USERS] Horrible Looking WMS Raster Imagery
> >
> > On 1/23/06, Brent Pedersen <bpederse at nature.berkeley.edu
> > <mailto:bpederse at nature.berkeley.edu>> wrote:
> > > have you tried using image/jpeg?
> >
> > In addition to fetching data from the remote WMSes as
> > JPEG, it is also necessary for mapserver to generate 24bit
> > output (JPEG or PNG24 for instance). I don't know how to
> > do that with Chameleon myself, but I'm sure there is a setting
> > somewhere.
> >
> > I think Ed is right that the problem is 24bit to 8bit color
> > conversion with correspondingly poor color resolution.
> > Given sufficient blotchiness from this conversion it can
> > even appear that spatial resolution is degraded (though it
> > isn't actually).
> >
> > Best regards,
> > ---
> >
> > I set the clouds in motion - turn up | Frank Warmerdam,
> > warmerdam at pobox.com <mailto:warmerdam at pobox.com>
> > light and sound - activate the windows | http://pobox.com/~warmerdam
> > and watch the world go round - Rush | Geospatial Programmer for Rent
> >
> > ------------------------------------------------
> > Brent,
> >
> > Thanks for the suggestion. I switched the output from png to jpeg - but
> > no change (the jpeg might have looked a little worse??). Still, the
> > crux of the matter is, I suppose, that these images are displayed
> > through a context file. The rasters are coming straight from their
> > "original" (perhaps) source, which doesn't allow me to specify how the
> > image is displayed, but merely that an image is displayed (furthermore,
> > the context file is automatically generated by the "Save Context" widget
> > in Chameleon).
> >
> > And an addendum to my last message: I did find output specifications in
> > the documentation
> > (http://mapserver.gis.umn.edu/docs/reference/mapfile/outputformat/), but
> > I don't have the opportunity in this instance to specify the output in
> > this sense.
> >
> > Jennifer
> >
> > -----------------------------------------------
> > Hi Frank,
> >
> > Thanks for the response, Frank. It is sounding more and more like this
> > is a question I ought to forward to the chameleon list - because I am
> > also not sure how to generate 24bit output with chameleon!
> >
> > I appreciate the much needed direction!
> >
> > Thanks all!
> >
> > Jennifer
> >
>
>
> --
> Jeff McKenna
> DM Solutions Group Inc.
> http://www.dmsolutions.ca
> _______________________________________________
> Chameleon mailing list
> Chameleon at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/chameleon
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.maptools.org/pipermail/chameleon/attachments/20060124/b9a2e7ca/attachment.html
More information about the Chameleon
mailing list