GeoServer Rendering transformations in CSS

[dwins]

GeoServer has a cool feature where you can use a WPS Process to modify data arbitrarily on the fly as part of your style. It would be awesome to support it in CSS. The render-transformations branch is basically ready to go but since GeoTools currently ignores the relevant property when serializing styles it doesn't work well.

[aaime]

Mumble... anything I can help with?

[dwins]

Well, I guess it is possible this has been fixed already in GeoTools; I haven't looked at it in a while. If not I think it would be a purely GeoTools fix to include the transformation process in SLDs encoded by the GeoTools encoder.

Since implementing the render-transformations branch though I've been thinking it would be nice to come up with a specialized notation for processes though. Rather than

• {
  transform: [gs:Contour(parameter("data"), parameter("levels", 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800))]
  }

It would be nice to do something more like:

• {
  transform: [gs:Contour(levels=[1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800])]
  }

I started experimenting with this a while ago in https://github.com/dwins/woops but ran into trouble with the GeoTools WPS client so didn't get too far. (The plan was to put together a command-line WPS client and then repurpose the command language, maybe a more direct approach would be more effective.)

[aaime]

As far as I can see SLDTransformerTest has a test to round trip a rendering transformation, so it should be good gt wise.

I agree the second syntax looks nicer.

The WPS client is still quite a bit far away from being useful (I mean, I've used it a couple of times for limited purposes, and it worked once I've patched it ;-) ) but yeah, those two seem two separate topics :-)