[Radiance-general] water - any news???

[Greg Ward]

Hi Guilio,

I'm still catching up with e-mail after a week's absence.  This one  
also required some thought...

It would be a fair amount of work, but it's possible to use rtcontrib  
to give you a nice incident light field on the bottom of a swimming  
pool.  You could then model this as a glow source and see it  
reflected back through the wavy dielectric surface of the water.  If  
you were extra-ambitious, you could even model the water's surface as  
a height field, but it would have to be really choppy for that to  
even matter, visually.

I would have to spend some time to create an example of this  
approach, but the basic idea is to flag the surfaces defining the  
underwater portion of the pool so they can gather rays using  
rtcontrib.  You would have to also define bin numbers corresponding  
to pixels in (5) low-resolution images you would create and map back  
onto the surfaces for subsequent rendering.  The rays given to  
rtcontrib would correspond to the solar radiation on a rectangle  
covering the pool's surface.  Normalization for this data would  
require a bit of math as well, but it's all doable.  I won't call it  
easy.

-Greg

> From: "Giulio Antonutto" <Giulio.Antonutto at arup.com>
> Date: November 8, 2007 3:48:07 AM PST
>
> “You might be able to get Radiance to find the sun for a still body  
> ofwater using the 'prism2' type, but you have to know what you're  
> doing.How important is this to you?  If you're just going for looks  
> and notvery interested in physical accuracy, go ahead and use  
> 'glass'.  Atleast you will be able to see the bottom of your pool  
> that way.-Greg”
> Just going through and old question… simulating water properly.
>
> Did anybody do anything bout this in the last 10 years? Any news?  
> All still using glass?
>
> For who may not know the interface/dielectric primitive struggle to  
> solve the direct light component, hence it is not trivial to  
> simulate a pool with Radiance.
>
> We incidentally realized of this problem when dealing with water in  
> daytime, which indeed looks very dark…
>
> (in fact for nighttimes shots a wavy mirror is often good looking  
> enough…)
>
> Any input?
>
> G>
>