Bruno Cabasson wrote:
> For cumuli, the problem is different than clouscapes and quite tricky. I think
> I'll have to do with single clouds. But I am afraid that the turbulence feature
> is not completely appropritate for the 'roundness' of cumuli. I tried with the
> current system, but it is not suitable for cumuli and I could never get
> acceptable results (mainly because the density is based on standard patterns).
> Perhaps a particle system will be necessary, but I absolutely do not master
> that. Advice/ideas welcome.

   For my cumuli I used the object pattern, using as object a conglomerate 
of spheres, distributed in a loop to resemble the shape of a cloud, then 
used this with media and turbulence. But as you said, I never got realistic 
results with turbulence... it should be my fault, because Gilles used it 
very well on his DF3 clouds.

> It can define the terrain either as
>     *) pigment-based function (user-defined), allowing overhangs (isosurface)
>     *) Height field out of pigment function
>     *) Height field out of image_map
>     *) Image_map generation from pigment function

   I would add "isosurface based on a external heightfield". I have some WIP 
on this subject, and it is very handy, as you can control the general shape 
of the terrain with a heightfield "guide" and then add overhangs with an 
extra function. I even developed a method to add the overhangs only on the 
vertical parts, although it is very trick (requires calculating a "slope 
map" of the heightfield first).

> It can (will) define the sky as
>     *) Media, like the skies I already posted. Allows cloudscape to cast shadows
>     -) Sky-dome image map (probably a sphere)
>     -) DF3 generation for single clouds.

   For the skydome imagemap (which can be very useful indeed), take into 
account the possible output as HDR. This means getting a good balance 
between the intensity of the sky and the sun.

>     *) Water

   Plane, heightfield or isosurface? For close-ups to the shoreline, an hf 
or isosurface is very convenient.

  > One big piece will also be to incorporate vegetation. It can use 
POV-Tree, and
> stuff from PlantStudio or so. I would like to provide for pattern-based
> placement macros (I already have something for that).

   I think it's better to let the user supply their own plants/trees, you 
only need to provide the placement macros.

> I want all be declarative, so that a MMI can be easily plugged. For example, for
> the last version of my sky system, and for the sky that is currently rendering:

   Looks like the right direction to me...

> PS: By essence, skies require intensively the media feature. What about media
> with 3.7?

   IIRC, it will get ride of the container artifacts you are going to meet 
with individual clouds... ;)

--
Jaime

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