Horrible Looking WMS Raster Imagery

[Brent Pedersen]

have you tried using image/jpeg?


On Jan 23, 2006, at 8:39 PM, Jennifer Zeisloft wrote:

> 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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