Le Sun, 19 Apr 2009 23:20:47 +0200, Bill Pragnell  


> Tricky things, clouds. All my previous experiments with media clouds  
> have been
> slow, unrealistic, and fiddly. Gilles' df3 technique is sly, and his  
> example
> images beautiful. However, I've always wanted a cloud macro that will  
> 'just
> work' in a scene, without the need for external tools and without the  
> memory
> consumption of hi-res df3s.
>
> This image is a decent result from a set of macros I've recently been  
> developing
> - it rendered in ~30 mins on my 1.8GHz macbook, which I think is very  
> good for
> 'pure' object-pattern-based media (this is without aa - unfortunately it  
> takes
> a lot longer with aa).
>
> Using a blob as the pattern template makes the rendering much quicker,  
> and
> lowering the media aa_level is also a great speedup I'd never tried  
> before. My
> basic cloud macro currently has 11 parameters, which sounds like a lot,  
> but this
> includes location and size, turbulence, solidity and so on, which makes  
> tweaking
> a lot easier. I've also got a quality parameter, the lowest setting of  
> which
> just uses the solid blob objects - very handy for shape and location  
> checks
> (and also looks pretty surreal!).
>
> Anyway, this is a wip so I'll post more interesting results as I get  
> them...


Hello POVers.

Perhaps some people here will remember me. It's a loooong time I was not  
present among the POV community. Real life took me away from you (sigh...)  
for months and from my POV-related projects. The main project is still  
alive and is called TerraPOV. It deals with landscape scenes, inspired by  
Terragen, and I was mainly focusing on atmosphere and cloudscapes, which  
is a difficult exercise if you want to have quite-realistic results. I had  
some encouraging renders. I came back on POV forums and to TerraPOV  
recently. My new machine (overclocked Q6600) allows a step forward. I feel  
like I can say something on this thread about clouds.


TerraPOV has 3 major dimensions:

     1) Atmospheres & cloudscapes/single could
     2) Terrain generation/texturing
     3) Preview & other user-friendly features

I also remember that I promessed you a tutorial for the principles ruling  
TerraPOV's atmophere & clouscape system. I will keep my promess soon.

Here are a few things I can get, among them is the last render I got last  
night (atmo_demo5bis.png and atmo_demo5ter.png), based on a previous test  
scene, but with higher settings. The problem I have now is to find a  
solution for multi-layer cloudscapes because monte-carlo integration can  
only be in a single container. Until now, cloud layers are contained  
within spherical shells. I am currently trying to find a way to have  
multiple layers (2 or 3 are enough for most cases) within a single shell  
container without setting too many intervals or samples for the media.

The last picture 'atmo_demo5ter.png' is the same as 'atmo_demo5bis' shows  
what can happen with 2 layers, which is more visible at low elevations  
(resp 3deg and 18deg). The bottom layer is dark because integration only  
occurs within the shell and does not take into account what happens above.  
You can see that the top layer bahaves as It could be expected.


I am very happy to be back, and I sincerely hope I can get regular  
availability and time here. It is always a nice pleasure to be with people  
around here.


Bruno

-- 

http://www.opera.com/mail/

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Attachments:
Download 'atmo_demo5bis.png' (405 KB) Download 'sky_21.png' (234 KB) Download 'sky_23_2.png' (350 KB) Download 'atmo_demo5ter.png' (299 KB)

Preview of image 'atmo_demo5bis.png'

Preview of image 'sky_21.png'

Preview of image 'sky_23_2.png'

Preview of image 'atmo_demo5ter.png'