We have discovered an interesting default behavior using WMS in ESRI
ArcGIS software.  This is not really a 'bug', just the way ArcMap
handles WMS requests.
 
By default, ArcMap will assign a 'background' color to WMS, which by
default is white (255 255 255 pixel value).  There are a few of the new
WMS (Baxter 2004, SPOT) that have clouds which have some pixels showing
pure white (255 255 255).  Since by default ArcMap considers this the
default background color, it renders all pixels that are pure white as
transparent.  Thus you will see 'holes' in the clouds and can view
whatever layers are underneath them, which makes for curious mapping!
 
A simple solution is to go into the layer properties, Advanced tab, and
turn off the checkbox that makes the background value transparent.
 
MEGIS will go through and make this change on the LYR files we host on
the WMS web page within the next few days.
 
This behavior is not apparent in other WMS clients tested including
Google Earth, QGIS, and Gaia.
 
**********
Michael Smith
State GIS Manager
Maine Office of GIS
 
State House Station 174
264 Civic Center Drive
Augusta ME 04333-0174
(207) 215-5530
 
Member, Maine GeoLibrary Board

 


-----------------------------------------------------------------------
This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion list for all Maine GIS Users. If you no longer wish to receive e-mail from this list, you can remove your name and email address yourself at the this web address:

http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1

Or,you may also request that your name be removed by sending email to:

[log in to unmask]