Horrible Looking WMS Raster Imagery

[Jennifer Zeisloft]

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


On 1/23/06, Ed McNierney <ed at topozone.com> wrote:
>
> 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
>
>  ------------------------------
> *From:* UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] *On
> Behalf Of *Jennifer Zeisloft
> *Sent:* Monday, January 23, 2006 10:00 PM
> *To:* MAPSERVER-USERS at LISTS.UMN.EDU
> *Subject:* [UMN_MAPSERVER-USERS] Horrible Looking WMS Raster Imagery
>
> 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
>
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