PDA

View Full Version : Can't get nice ocean refractions on a swimming pool ground


robitabu
12-11-2009, 04:26 PM
Hi again,
I'm going further with my swimming pool simulation using the oceanShader. Now I'm concerned about getting a nice refraction lighting on the pavement of the pool, under the water.

I'm trying to get something like this: http://www.flickr.com/photos/grobledo/2447316752/ with a nice scattered light reflaction seen from above.

As I understand, that lighting is a combination of two reflections, the first on the water surface and the seconda caused by the light going through the water surface and reflecting back from the pool pavement. In fact, as can be seen in picture http://www.flickr.com/photos/king-edward/873378860/ the pool floor is lit in much the same way.

This second reflection is achievable only if light get refracted at the water surface downwards and I guess it has to do with caustics, but ... well ... I really never touched caustics before and even fooling around a bit with it I can't get _nothing_ like this. I'm shure I'm missing something crucial.

The scene is lit by a key Spotlight and a few very low intensity filling spotlights. I'm willing to use G.I. and F.G. (with which I'm confortable enough) ... and Caustics if needed.
Currently it renders like this (without G.I. and F.G.):
http://www.laubfrosch.it/tmp/swimming_pool_01_thumbnail.jpg (http://www.laubfrosch.it/tmp/swimming_pool_01.jpg)

still not quite what I'd like to get but I'm getting close.

Any hints about that? Anyone having a suggestion, a link to a tutorial or anything about this peculiar simulation?

mandark1011
12-11-2009, 06:42 PM
if you type "free caustic generator" into google you will find a nice tool for achieving a caustic fake. Then just project the animated texture onto the bottom of the pool.

Whenever I do water..unless there is an obvious movement behavior to the water, I generally just fake the caustics, saves a ton on render times, setup etc and is usually beliveable.

good luck

robitabu
12-11-2009, 07:44 PM
if you type "free caustic generator" into google you will find a nice tool for achieving a caustic fake. Then just project the animated texture onto the bottom of the pool.

Whenever I do water..unless there is an obvious movement behavior to the water, I generally just fake the caustics, saves a ton on render times, setup etc and is usually beliveable.

good luck

Nice trick mandark1011 :-) And of course nice little software :-)
Well, far from being the definitive solution, I wonder what happens when I animate the ocean displacement ... but for stills it's a quick and dirty hack that does the job. Thank you.

Nevertheless I keep on investigating on how get it done using the scene lighting.

Bonedaddy
12-11-2009, 09:48 PM
Honestly, almost nobody ever does physically accurate caustics. Projecting an image sequence is going to be a lot faster and more art-directable.

robitabu
12-11-2009, 10:07 PM
Honestly, almost nobody ever does physically accurate caustics. Projecting an image sequence is going to be a lot faster and more art-directable.

You know what? I'm giving it a shot anyway, how could I learn without even trying? ;-)

Bonedaddy
12-11-2009, 10:52 PM
Sure, there's plenty of tutorials out there. It'll help you wrap your head around MR's photon setup at the very least.

robitabu
12-11-2009, 11:44 PM
Honestly, almost nobody ever does physically accurate caustics. Projecting an image sequence is going to be a lot faster and more art-directable.

Anyway I find your point of view interesting. Since rendering is faking reality why not fake it in an easy way? Right :-)

robitabu
12-13-2009, 09:59 AM
I have to say the Caustics Generator has done the job well. After tweaking the image sequence and the swimming pool shader and textures I did get the result I was looking for using no real Caustics at all.

I just wanted to let you know you pointed me right. This is what it looks now:
http://www.laubfrosch.it/tmp/swimming_pool_02_thumbnail.jpg
(click to view a short highres animation) (http://www.laubfrosch.it/tmp/swimming_pool_02_xvid.avi)


I will still try to get it with real Caustics, since I've put it in my todo list. Have a nice day :-)

CGTalk Moderation
12-13-2009, 09:59 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.