I thought I knew how to do this but clearly I dont...

I want to populate a square landscape with a message (sounds lame i know, but bear with me), the message wants to be written in trees.

I figured that I could assign an image map with the "variable density" node, set it to object parametric and populate, but alas this doesnt work.

I know its probalby an easy one, but my sleep deprived brain has forgotton how to do this.

any tips/links please?

Like so?

I could send you a file, but if I recall, I just built it off the ecolo-go! file in the "Samples 1" collection from the Extras CD. Do you have that?

ah yeah exactly

ill check it out, thanks bud

Rich, you have the right formula, it should work. Set the map to flat (vertical) in the FE, and use bicubic interpolation (optional). Back in the material editor, you can edit the density filter so it is flat until 0.5 horizontal, this will act like a brightness/contrast filter.

brilliant thanks everyone :D

I got it sorted using all your tips, i think one of the major ones was havin ghe density filter the wrong way round (doh!) so thanks artpearl for that :D

I can send my sister her birthday card now and look like a half decent brother :P

thanks again!

You can either do it the way I have it with the black parts being the ones I wanted populated and the filter going down, or have the filter going up BUT click the little button on the top left in the FE (next to where it says "image"), that will inverse the colors, the parts that gt populated will be the white ones.
This is the official vue definition : white=high density. But I dont like it, my brain associates white with 'nothing' and black with 'lots', so I reverse it. 
Anyhow, glad it helped.
By the way - if you need it to populate accurately you may need to up the sampling quality - as you can see I'm up to 500% in my example. It takes longer to populate though.
Another way to do it is to use mixed material  - one with eco population and one without, and control the distribution of the two materials with a map. Some gurus say this goes faster, I havnt tested it myself yet. (and if what you are populating is a terrain you can paint the populated material in the terrain editor)

i think that in my brain thats what i was trying to do actually, but did it in the wrong place. never mind its done now :)

i agree, black seems more like it should be high density, but i think it goes on rgb values where black = 0 and white is 255