Displaying Mapserver raster in ArcMap gives 256 colours

[Ed McNierney]

Brendan -

Although this may change with different versions of ArcMap, my
experience is that ArcMap would select the FIRST image format type
advertised in the WMS service's capabilities document, and provide no
option for the selection of a different format.  Take a look at your
GetCapabilities result to see if that seems correct.

We ended up creating two distinct WMS services for ArcMap users - one
for topo maps and one for aerial photos.  The only reason we did that is
so we could force ArcMap to request PNG images in the first case and
JPEG in the second.  And as to Frank's comment about the QUALITY of
JPEGS, we found that QUALITY=80 for our aerial photography was virtually
indistinguishable from any higher number, so we use that value and no
one has ever complained about the quality of our photos.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Frank Warmerdam
Sent: Friday, October 13, 2006 10:39 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Displaying Mapserver raster in ArcMap
gives 256 colours

POWER Brendan wrote:
> I have installed ms4w on a windows box with GDAL, etc...  From here I 
> created a sample map (mapfile below) sourcing data from ecw images.
> When I use the WMS service via an intranet, I get a full colour image 
> through the GetMap &LAYER command, however, when using ArcMap, I only 
> get a 256 colour image.  Is there something I am doing wrong?
> Any assistance would be appreciated.

Brendan,

It may be that ArcMap picks a different format to fetch.  You might
check the logs to see what FORMAT= option ArcMap is using.  I think
there are "standard outputformats" still offered even when you declare
your own output format(s) (though I'm not sure about that).

> NAME TestMap
> STATUS ON
> SIZE 640 480
> EXTENT 116 -24 120 -22
> UNITS METERS
> SHAPEPATH "d:\Zone_50"
> IMAGETYPE FCADIType
> OUTPUTFORMAT
>   NAME FCADIType
>   DRIVER "GDAL/jpeg"
>   MIMETYPE "image/jpeg"
>   IMAGEMODE RGB
>   EXTENSION "jpg"
>   FORMATOPTION "INTERLACE=OFF"
>   FORMATOPTION "QUALITY=100"
>   FORMATOPTION "OUTPUT_TYPE=RASTER"
> END

Note that JPEG with QUALITY=100 is substantially larger than with
QUALITY=95, but is not measurably better quality.  The libjpeg docs
discourage use of QUALITY over 95.  I recently corrected the GDAL docs
to address this, and to clarify that QUALITY=100 is *not* lossless.

What is OUTPUT_TYPE=RASTER supposed to do?

Best regards,
-- 
---------------------------------------+--------------------------------
---------------------------------------+------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo,
http://osgeo.org