Comments on: Mapserver GIF Transparency

By: gisuser

gisuser — Wed, 20 Sep 2006 13:38:34 +0000

For gifs, you need to use this in your .map file:

OUTPUTFORMAT
NAME gif
DRIVER “GD/GIF”
MIMETYPE “image/gif”
IMAGEMODE PC256
EXTENSION “gif”
TRANSPARENT ON
END

by default, transparent is NOT on.

By: Paul Tildesley

Paul Tildesley — Wed, 24 May 2006 23:09:26 +0000

Chris,

Thanks for the tips. I have followed your advice and now my overlays have transparent backgrounds as planned. I can confirm that you do need to turn off interlace for the PNG images.

One quirk that I found - I asked for one of my layers to be black (0 0 0) and the background for this was not transparent. I changed the colour to (1 1 1) and the background was transparent.

It would be nice to know why transparency works for PNG images but not for GIF images but at least I can continue with my work.

Thanks again for your help.

Paul.

By: Christian

Christian — Wed, 24 May 2006 20:59:32 +0000

Ok, never mind… Using PNG for the RIGHT WMS request magically worked…

Funny how stuff works when you do it right, isn’t it?

Thanks for the hint!

By: Christian

Christian — Wed, 24 May 2006 20:49:51 +0000

Hi Chris,

I only have a problem with (non)transparent background, when GoogleEarth requests data from my Mapserver where there is no data to see.

Disregarding all TRANSAPRENT settings it just floods the earth with the set IMAGECOLOR.

In cases where GE requests a part with actual Mapserver coverage all is good (inculding transparency)

Any clues?

(another) Chris, Brazil

By: Chris Tweedie

Chris Tweedie — Wed, 24 May 2006 13:40:25 +0000

Hey paul,

I did solve this using PNG and from memory it was turning off interlacing in the OUTPUTFORMAT for image/png

Flick me a mail if you havent heard from me tomorrow with the relevant mapfile excerpts

By: Paul Tildesley

Paul Tildesley — Tue, 23 May 2006 23:59:22 +0000

Hi Chris,

I have set up a WMS with MapServer and am now trying to view the layers with Google Earth and I have come up against a similar problem to you. I am serving satellite imagery of sea-surface temperature (raster files) with transparent land and I can view that just fine with Google Earth - the Google land shows through. I am also serving up some overlays - coastline, continental shelf edge and fish sample locations. The data for these are ESRI shape files and I cannot get Google Earth to render the background as transparent.

If you send me an email I can send you the map file and KML file if you are interested.

If you have solved the transparency problem, I would love to hear about it.

Regards,

Paul (Hobart, Tasmania)