[mapserver-dev] Need mapfile for AGG and Transparent overlay

Lars Lingner ml at lingner.eu
Thu Nov 5 02:33:36 EST 2009

Stephen Woodbridge schrieb:
> Thomas,
> I think this is mostly directed at you. I have been using your sample
> OSM mapfile and it is really great - Thanks for putting this together.
> It raises an issue that I think needs to be dealt with, but maybe I'm
> missing some feature that is already implemented.
> My use case is that I need a single mapfile that I can use for
> antialiased rendering like your file above, but I also need to generate
> transparent overlay images of just the road network by selecting just
> those layers or group. For example, in Openlayers, I need to have google
> like controls for [map][hybrid][etc] where the [map] view is like above
> and the hybrid view is satellite imagery as an OL layer and transparent
> road network overlay in OL.

I think I'm doing exactly this within discOSM [1]. So I have raster
layer (e.g. hillshade, contours) and put just the road network on top of it.

Basically I'm using this

      NAME agg
      FORMATOPTION "transparent=off"
      MIMETYPE "image/png"

For this you need to have MapServer compiled with the "experimental
rgba" flag (don't know the exact flag name yet...)

If you need the whole mapfile you could just download one of the iso
images I offer there, which have the whole setup on it.

The mapfile is based on Thomas work, but very modified to meet my needs.

You can also send me an email directly, I would dig it out for you.


[1] http://www.lingner.eu/discosm_online/

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