[Geomoose-users] Image display covers up layers beyond its extent

[Dan Little]

Images being served as a JPEG are not "see through" so if you have an ECW that covers the City, mapserver will fill the rest of the image with a color (typically white).  Transparency comes into play, because if you serve the image as a PNG or GIF then the "white" becomes "see through" (aka "transparent").

This isn't a limitation of Mapserver or GeoMOOSE, it's a limitation of the JPEG format.




________________________________
From: Jim Dahl <jim.dahl at mail.co.douglas.mn.us>
To: Dan Little <danlittle at yahoo.com>; geomoose-users at lists.sourceforge.net
Sent: Friday, November 7, 2008 2:01:50 PM
Subject: RE: [Geomoose-users] Image display covers up layers beyond its extent

Message  
The 
image is an ECW but JPG acts the same way.  My question is why does 
transparency come into play when I do not want to see under the image, I want to 
see beyond the extent of the image.  For example the image is 1 mile by 1 
mile and it still covers up the whole county.  Is that because the 
mapserver still thinks the image is county-wide?
 
jim
-----Original Message-----
From: Dan Little  [mailto:danlittle at yahoo.com] 
Sent: Friday, November 07, 2008 1:55  PM
To: Jim Dahl;  geomoose-users at lists.sourceforge.net
Subject: Re: [Geomoose-users]  Image display covers up layers beyond its extent


What type of layer is it?

If it's raster it's a little harder to  deal with because it's probably being served as a JPEG and JPEG's don't  support transparency.

If it's a GIF then it's pretty easy to just set  the image as transparent, so if there isn't any data it shouldn't show  up.




________________________________
 From: Jim Dahl  <jim.dahl at mail.co.douglas.mn.us>
To: geomoose-users at lists.sourceforge.net
Sent: Friday, November 7, 2008 11:08:54  AM
Subject: [Geomoose-users]  Image display covers up layers beyond its extent


Hope to have  better luck with this question..  Does anyone know how I can keep an  image that covers only a city from covering up another image below it that  covers the entire county?  The extent doesn't seem to work for me in the  mapfile.
 
thanks,
 
Jim Dahl, GISP
GIS Coordinator
Douglas  County Public Works
509 3rd Ave  W
PO Box 398
Alexandria MN 56308
V 320-762-2933
   320-763-6001
F  320-763-7955


      
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