Lighting Maya Fluid System


#1

This has always troubled me, but I though I should concentrate on the sims more.
Lighting a fluids in maya is really weird (speaking out of my in-experience :hmm: ).

I’m attaching an image that shows where I am trying to compose the fluids into, along with the different results i am getting.
I tried with real lights off, then real lights on under the lighting tab in fluidsShape Node.
Light linking, light centric doesn’t seem to show fluids to unlink or link lights too…i was just trying that out.

So what is the best way to light fluids? how we give depth to it? it comes so flat when real lights are turned on sometimes, if that case how do we work around it, the playBlast and High Quality in viewPort gives much better look and the shadows and depth than in Mental Ray rendering with shadow method in segmented?
Is composting and working on the post the only way? :sad:

Thanks in advance for any help that comes this way - cause that’ll really help a lot. :thumbsup:


#2

its really sad, waiting so much for some one to come along and help :sad:


#3

Well, I have no idea what you problem is. Okay, the fluids does not respond to light linking and indeed compositing is the best way to integrate it into other footage.

But I often simply use default maya lights, turn raytraced shadows on, place it in the correct position and render with mentalray. Done.

And, yes, you are right, the detail in the UI often looks more detailed than in a final render.

To it looks as if you have a very dark color for your fluid.


#4

I’m not sure… Try to render fluids with maya software, yes it’s not so fast like mental ray, but it gives to you output image much closer to viewport like. turn on “real light” when you realy have light in you scene, and connect directional light parametrs to position of you light.
play with other parametrs in fluid “lighting”.


#5

Thank You for replying. :bowdown:
But I have tried what you have told me…
Sometimes I get a very good looking result like this - http://vimeo.com/31217152
However the same fluids if I take it to a scene with multiple lights then it becomes flat like in the image, regardless of whether it is Maya Software or Mental Ray for Maya.

I do the same thing as you haggi but things are changing when I am trying to compose it in a scene with other lights.


#6

OKAY, after going through forums, most of the fluid freaks are using basic 2 point ot 3 point lighting setup.
But they are either renders or playBlasts…
I did not find any composting…

So the doubt still remains :argh: , how to comp a fluid in a scene without making it look flat. :banghead:


#7

Easy answer would be is to look for Wayne’s “Gnomon fluid Dynamics DVD” & check the lighting he has done & explained in that. Use many lights with fluids is not successful always.


#8

Okay Vikki,
I have that with me. But my doubt is with composting it within a scene…how can you un-link those lights you have used for your scene?

So if there is no way, IS COMPOSTING THE ONLY METHOD?!
Rendering it in separate passes and then combining it?


#9

Do you have ambient lighting on in the fluidShape? Have you turned off the default light in the render settings? This is a long shot but are you working linearly in MR (this might reduce the contrast if you were)?


#10

Rochre,
Default light is off for sure but I will do a double check on ambient lighting and will post the reply soon.


#11

Do you have a lens shader attached to your camera? if so. Set gamma to 1.0 or leave at 2.2 1.8 etc. and set you lights to quadratic falloff. adjust intensity accordingly. this will also affect you colors (the would need an inversion of the gamma correction if you set it to 2.2 or 1.8.Obviously your directional light won’t have quadractic falloff but the others will.You could also try using MR lights instead. They will force quadratic falloff.


#12

I checked ambient light is 0.00 in fluid’s lighting tab
default light in Maya is unchecked but I do have a lens shader

“mia_exposure_photographic,” to my renderCamera but not to perspective, from which i rendered the above images.

settings of the lens shader, I have attached as an image.

I will look into what you have suggested once again and let you know

Thank You


#13

Well you shouldn’t be getting the results you are. I always render with MR and it comes out fine. Just going to have to double check everything. Self Shadow. Shadows on lights. lens nodes. Are you using FG? You’re photographics shader is set to the default gamma. set it to 1, render with that and see if it looks better.


#14

Rochre I am not using the lens shader in Persp Camera but a in renderCamera.

Persp is where I am rendering for the tests, does that lens shader affect then?


#15

No lens shader shouldn’t be conncected to your perspective camera. The only time a lens shader would be connected to all your cameras would be if you had create a sun and sky system. Howeever if you plan to be rendering out of a camera with a lens shader then that’s probably the camera you should be basing your final look on. That said. I’m plum out of answers for you. Can you post the scene file?


#16

No lens shader shouldn’t be conncected to your perspective camera. The only time a lens shader would be connected to all your cameras would be if you had create a sun and sky system. Howeever if you plan to be rendering out of a camera with a lens shader then that’s probably the camera you should be basing your final look on. That said. I’m plum out of answers for you. Can you post the scene file?


#17

Ya I am aware about the MR Sun & Sky.

Rochre, the thing is I am sure all this effects are color corrected done more justice in post, becuase Wayne keeps emphasizing on post on his DVD, he tells the sim has to look good first (priority); And then you go do all color corrections and add things like Motion Blur in post …

Even though I know we can do it in post, my doubt, I should rather say CURIOSITY…about how these pros in VFX comp a fluid into the scene and match the lighting without a flaw, I mean you still need a good base lighting to edit in post.

I think I should make my query more transparent, so here goes.

  1. How to light a fluid to match your scene lighting. Even if its color corrected in post there has to be some lighting done to match the scene. How many lights to use or at least a good starting so the fluids won’t render flat shaded. Sometimes turning of “real lights,” gives awesome results, not to mention playBlast, often looks so cool.

  2. If it’s not dependent on post then how to un-link the scene lights from fluidSystem to it won’t render flat.

  3. After rendering in Hardware render buffer (hrb), Mental Ray & Maya Software render renderer
    Mental Ray and HRB is giving the best results (at least to my tests). And some HRB is way to cool but can we use it? in final shot? do they use it?

Now to some people this post may seem noobish, but this something I face almost all the time cause I always do sims on a good lit environment. So I am really curious.

By the way Rochre the scene file has been attached to the this post, do check it out and let me know. And thanks for all the help mate.

Gov


#18

I’ve taken a look at your scene file and there are a couple things you can do. First I’d like to tell you how I render and light fluids. All my fluids are rendered as separate elements that I then composite back into the final render using a composting program. When I light a fluid I try to fake as much of the lighting as possible. You don’t have to match it perfectly.

Fluids are lit a little different that geo. The main difference is shadowing. The reason you have flat shading is because the majority of you lighting is not casting shadows. A light that does not cast shadows completely penetrates your fluid and illuminates all parts of it equally. I would start with one keyLight that is casting raytracing shadows. Always start simple. My typical lighting set up consists of one direction light casting shadows and one ambient light, which is used as a base luminance. If I need to add more shadowing detail I can add another directional light to highlight the areas that I want to see. (again casting shadows.)

Your scene basically has a moon light that is your key light and a backlight being cast from your lamp. Basically you can set up a directional light for you moonlight, and ambient for fill lighting, a secondary directional for some highlights, and a point light with falloff for your lamp. That should give you the basic lighting you need. Then all you have to do is composite the images together in aftereffects or nuke with mattes, holdouts, and shadows.


#19

Hey Calibrix,

           Yes I actually did something similar to your suggestion and I got this - http://vimeo.com/31217152

I mean two Dir-lights and one point-light, a basic three point lighting setup.

So i guess my doubt is clear regarding this.

*** COMPOSTING is the best way to match fluids into a scene, and do the tweaking on NUKE/AFX or whatever***

Great… :beer:

Thanks to all who took time to reply. Appreciate it :bowdown:


#20

Please don’t feel I am comparing or being biased but

fume fx has an option of light-linking.

I don’t understand when fluids is such a HUGE area in Maya’s dynamics, not having a option like that. Then all this fuss over lighting can be avoided right?!

Well there must be a strong reason why they don’t have it, but who cares Maya rocks anyways. :slight_smile: