Wasn't it ShiJie who wrote:
>Dear NG,
>
>No matter what I do it's really difficult to have the same render of
>Terragen for my terrains in my Pov.. so I decided to try this trick on to
>render my background in Terragen and the objects in Pov and then use Gimp
>(my only photoeditor) to merge the background with the objects.
>
>I am not yet very professional at this, so some advises would be much
>appreciated. I try to but a lightsource exactly at the position of the sun
>where it is declared in Terragen so that the shadows would be realistic
>when I mix the images... Then I try to select part of my pov image by color
>in Gimp and cut them and then put them in the background that I created in
>Terragen. I am still feeling that I might get a bad work on this .. and
>many will notice that the two images are made at different times. I was
>looking for a way to find a script in Gimp that seperates the image and the
>shadows into different layers for each image (by some color selection
>method.. etc.) but I couldn't find one .. I think this functionality one
>can find in photoshop..
>
>I would of course just prefer to have all the image rendered in pov (after
>some magical teragen-forrester combo to produce the pov).. but that's
>really looks impossible (and I have limited time... I want to finish the
>picture this month) as pov really doesn't produce the terrain scenes
>exactly like that in Terragen.
>
>Would appreciate any comments/advises/suggestions.


Rather than "selecting parts of your POV image by colour", wouldn't it
be easier to render your POV objects onto a transparent background.
[Ensure that your output file type supports transparency (e.g. PNG
format by using +FN) and add +UA to the command line to generate
transparency.]

The Gimp supports image transparency, so you just copy and paste your
pov objects onto your Terragen background image, where they appear as a
floating selection (just the opaque parts are selected) which you can
then drag into place. You can then drag the floating selection into
place and, if necessary, turn it into a separate layer.


Another different approach is to do your image compositing in POV. Paint
your Terragen image onto a backdrop as an image_map. You need to be
careful not to cast any shadows onto it, which can be achieved by
setting the backdrop to finish {ambient 1}. I believe that the tricks
used in the supplied incdemo/screen.pov can be used to accurately place
the backdrop object so that it exactly fills the POV screen.

-- 
Mike Williams
Gentleman of Leisure

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