underwater caustics in maya - dotted?

starogre · Oct 2012

Hey so I'm trying to learn the 'high quality way' of caustics, rather than dropping a preset or 2d ocean texture on everything. So I followed this tutorial here - http://www.creativecrash.com/tutorials/underwater-lighting-parti_volume--2

and i can't for the life of me figure out why the caustics look polka-dotted. I've tried a ton of things to modify it - increasing photons from 500k to 1m+, changing radii and merge distance in the caustics settings, accuracy of the caustics, removing the parti volume node, etc. I have only been able to get them to show up darker, less sparse, brighter, and too blurred, but no crisp connected edges. Even tried changing the properties of the ocean displacement map plugged into the dielectric material...

Anyone recognize this property and/or have any idea what might cause this?

Edit: also brought the spotlight aka particle emitter closer thinking they wouldn't spread out so much... and changed the caustics shape to cone rather than box...no luck

BARDLER · Oct 2012

Well the first question to always ask is did you render using Mental Ray, and not Maya Software?

starogre · Oct 2012

yep, definitely! even tried boosting final gather, global illum., all the caustics numbers way up, etc. the tutorial's caustics are even dotted in their final render, and no one in the comments complains about it.

i found another tutorial that doesn't have this problem, a video tutorial by digital tutors- but they don't implement the parti_volume for the light ray 'fog' underwater. but i wanted the light rays.

Ark · Oct 2012

Posting a pic would help. I assume you have the caustic options enabled under the render properties?

starogre · Oct 2012

Sadly I'm on my phone at the moment but on the last page of the tutorial (4th part) my render looks exactly like the final product of the tutorial. The problem is the caustics are all dotted looking just like the tutorial's final image. It's just that the tutorial didn't bother to finish polishing the caustics so I'm not sure what's causing the spotted look of the caustics

Ark · Oct 2012

Not to sure what you mean by the spotted look, but if you want it to look smoother, you can try increasing the amount of photons, which will also increase render time. The parti-volume node could probably be replaced with light-fog aswell.

starogre · Oct 2012

If you compare the caustics of the water to a photograph you'll notice the render's are made up of dots and not crisp and smooth. I already tried increasing the photons. Does light fog get affected by the refractive surface of the water? Or would the fog shine through the water completely? I want the light ray fog to animate with the caustics in the end.

starogre · Oct 2012

If you compare the caustics of the water to a photograph you'll notice the render's are made up of dots and not crisp and smooth. I already tried increasing the photons. Does light fog get affected by the refractive surface of the water? Or would the fog shine through the water completely? I want the light ray fog to animate with the caustics in the end.

Ark · Oct 2012

Light fog is probably a post-process effect so your probably better of sticking with the parti-volume if you want reflections.

Again for the end result, your better of posting a picture.

starogre · Oct 2012

On the left is my render, on the right is a photo. As you can see I'm getting spotted caustics and I can't figure out why. I've listed off a bunch of stuff I've tried messing with in the first post. Anyone know what might be causing this?

Ark · Oct 2012

Well comparing your render to how something is supposed to look can be debated all day. That's what most are trying to achieve in CG.
Still if you look in the photo, there's still some noise in there.
Have you tried blurring the ocean texture? Or at least messing with the ocean textures settings?

starogre · Oct 2012

I have an ocean1 texture plugged into the displacement map of the dielectric material on the water surface. It seems to look smooth to me!

I've messed with the size of it as well. If i make the waves smaller basically, The same size dots still show up at the bottom to try and make up the smaller patterns which is interesting cus then it looks all messy.

starogre · Oct 2012

If my render was more 'noisey' than I could accept it. But the dots are all lined up such that it looks too mathematical to me. Edit: Plus, like I said, If i try and make the caustic patterns any smaller, they degrade into nothingness because the dots that make up the patterns stay the same size. Then it just looks like a giant noise texture

Brendan · Oct 2012

The problem appears to be the resolution of the 'large' waves in your render. Maybe make a much higher-res texture for it, as well as detail normal map and blend them properly (in your shader, the detail map should be reoriented so that 128,128,256 is whatever the base normal map value at that point is). Make sure texture filtering settings are alright, as well as any texture compression that may be going on (kill it).

If that doesn't help, then the only other thing I can suggest is fiddling with the number of samples each pixel interpolates between.

Changing the height of the water/place could be useful in determining what's the problem. See if this happens in more shallow or deep water!

starogre · Oct 2012

thanks for the tips, i'll try those out ASAP and report back!

starogre · Oct 2012

Ok, so I tried what you said, and it barely changed. I ended up trying to scale everything way down and it still didn't really work.

ALTHOUGH, NEWS FLASH: I followed this short 10 minute video tutorial EXACTLY MULTIPLE TIMES (the first free lesson part about actual caustics, not fake): http://www.digitaltutors.com/11/training.php?pid=302

WTF? Is there something wrong with the computers I'm using?? This is boggling my mind mannnnn

It looks like maybe it's something wrong with the ocean1 texture I'm using ontop? But I did the same thing as he did. Same with his render settings, step by step the same...

This is what it looks like though -

underwater caustics in maya - dotted?

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