interior swimming pool, caustics problem

[Dave Buckley]

currently have a interior swimming pool scene, with daylight system, sky portals at windows

 

i want my pool to have refractive caustics, i believe i have set everything up correctly

 

but getting the infamous "no photons stored after emitting . . . . ." error message

 

is there something i need to do to my sky portals when caustics is enabled.

 

i have caustics enabled on my swimming pool water surface, the daylight system and also in the render scene setup.

 

i am using photographic exposure with final gather and NO gi

[johnvid]

Cant you set up the scene with Direct lights for the caustics?

Did you sort out your text animatin problem, I posted a response but the system lost the post, Really you needed to elaborate, pictures would be a help.

[Dave Buckley]

i guess i could use direct lights but i want to be able to use the daylight system with sky portals. it must be possible???

 

 

the weid thing is, if i use the same setup but on an exterior (basically same but without sky portals or walls and ceiling) the caustics work, like on an exterior pool.

 

i'l update the text animation post with some images, but will need to draw some sketches and scan them in.

 

with regards to the text animation. if you imagine a cardboard box being unfolded so that it lies flat on the floor, i want to be able to animate it folding back up again. the only problem is i don't want to do it with a box, i want to be able to do it with text.

 

i've attached an image using a box as an example. eventually i want the text to look like each letter is made from cardboard,and has been put together like a cardboard box as shown in the example image.

[pixelperfectg]

i guess i could use direct lights but i want to be able to use the daylight system with sky portals. it must be possible???

Of course it's possible. Just follow the usual steps for creating caustic scenes:

1. Ensure your materials are properly configured to work with photons.

2. Ensure your geometry is properly configured to generate photons.

3. If you're wanting the mrSun to generate photons GI and/or caustic, use the photon targeting option of the mrSun.

 

Now, knowing that it's absolutely possible to setup a caustic scene with the mrSun & skylight portals, you have to decide if it's worthwhile. Perhaps simply using a caustic projection map on a light would provide decent results with faster render times, more control, and less hassle.

[Dave Buckley]

thanks for the response jeff however i'm not familiar with a caustic projection map.

 

i have however attached an image of the effect i want to achieve

[pixelperfectg]

thanks for the response jeff however i'm not familiar with a caustic projection map.

You use a bitmap of a caustic pattern in the projection map of a light source. Take a look in your 3dsmax/maps/lights folder, you'll see an example caustic projection map named "caustic.gif". There's also instructions on using projection maps in the help file under the topic of "advanced effects rollout" of light sources.

 

i have however attached an image of the effect i want to achieve

The reflective caustic pattern on the ceiling? Hmmm, I may be wrong here, but I don't think you'd actually see caustics like that in a similar 'indirectly lit' real world scenario. If the sun were actually hitting the water then yes I'd imagine a strong, pronounced caustic pattern like this would be visible.

 

For example, here's a few similar real world photos of indoor pools I found on a quick google search. I'm not seeing such a strong/pronounced caustic pattern on the ceilings:

http://www.lakeviewrise.com/DSCF0043.JPG

http://456js.co.uk/Images/SwimmingPoolB.jpg

http://image012.mylivepage.com/chunk12/973623/841/swimming%20pool%207.JPG

 

I know the point of your question isn't whether or not the reference image caustic pattern is physically accurate. It's that you simply want a caustic pattern to reflect from your swimming pool. I only mention the point about reality because once you solve the "no photons stored" issue in your scene, if photon caustics don't show up (or they aren't powerful), this may be why.

 

I could be completely wrong in my assumption here, but I think the person that created your reference render used a caustic projection map since that strong/clear pattern doesn't seem natural to me with the amount of sunlight in that room...so you may want to focus on that route.

 

A while back I remember seeing a few tileable caustic patterns on some website. I'll dig through my bookmarks to see if I saved it.

[Dave Buckley]

thanks jeff, i'll look it up in the help.

 

yeh i wasn't going for physical accuracy, just the effect because i like the render

[Justin Hunt]

for the light projecting, would you use an photometric area light or a plain old spot? (I'm too lazy to try for myself)

 

jhv

[johnvid]

THere is a program to export a 3Dmodel to flat paper for printing and cutting out to make a paper model, maybe you could use that to get the topology of what you want ? i think there is a program can't remember the names 3D Unfold or Something??

 

There is also a plugin for after effects that creates caustic patterns, you can then use those as a texturemap for the projection, the beauty of this method is you could also alter the rgb channels of the caustics separating them by slight amounts to give you a little chromatic dispersion instead of white.

 

I think the other comments are right the pool area may be too bright to get those caustics, they are also very well defined would like to know the settings on that, true caustics would not be created in the shaded areas of the water, so perhaps just one omni above the pool would sufice as the generator, never tried caustics with photons.... can anyone tell us if you get a better result that way or no difference???

[johnvid]

UNFOLD3D is the name of the program, though there must be a way to do it without it, maybe you had the right idea all along, with the texture map flatten thing, perhaps all you needed to do was simplify the spline for the font.

[Dave Buckley]

ok thanks i'l look into it.

 

joh i notice you are based in manchester??? what sort of work do you do??? i am in manchester myself just down in bramhall.

 

with regards to the caustics and sky portals at the windows???

 

if i keep the current setup, will i need to enable caustics on the sky portal object properties also???

 

or i was thinkin to just use an omni above the water with diffuse unchecked, and having that as the caustic generator rather than the daylight system???

[johnvid]

Dont work for cadassist by any chance you should have a hotline right to Autodesk, but perhaps this forum is a little different.

 

I didnt realise you where trying this with mental ray... as the image sample was vray....its a long time since i used MR, but yeah the omni above the pool might be the easiest method

Edited June 20, 2008 by johnvid

[mattclinch]

plain old spot with rectangular 'cone' is how i have done it in the past.

[Dave Buckley]

cheers matt but i wanna keep the daylight system in there providing the scene illumination.

 

john, funnily enough i do work for cadassist. u been their before for training or is that who you get your software from

 

and yes we do have a direct line to autodesk which is handy, but getting an answer is difficult. we usually have to wait until they put training on for us, for new software releases etc before we actually get to speak to anyone

[mattclinch]

you can still have your daylight system doing the scene illumination, then just use light projectors in spots to fire caustic light patterns at the ceiling/floor/wall/towel rail/ipod/bikini clad lady etc.

[John Dollus]

http://www.lysator.liu.se/~kand/caustics/

 

caustics generator - one of my all time favorites but then I used to live and breathe pools for a bit.

[Dave Buckley]

cheers for that link, do you have any example renders of work you have done using this program??

 

and also what is the workflow for using it?

[John Dollus]

I don't think I have anything done with it since 2003... a lifetime ago.

Basically, you follow the above suggestions - use the generator to create your projection map by setting the background color to black.

I would change the defaults to about 128 subdivisions, 16x supersampling, a high resolution and then blur it more in photoshop afterward a bit or downsample to smooth it out.

most of the settings are pretty obvious - depth is the distance from the water surface to the receiving plane, amplitude is the amount of water surface disturbance, etc.

you can export out a tileable animation sequence to use for animations as well - lots of fun!