Brazil R/S guy

[arcfx]

I have been using Vray for about a month now after using Brazil R/S for four years and Mental Ray in the side plus a good amount of Final Render. I am noticing Vray works much different on how it renders. I am have trouble keeping renders down to reasonable time. My renders look great because it is using real world solution to render, but sometimes I just want to render one or two quick passes with out rendering the whole shot. Also I notice you cant turn off second bounce G.I. on selected lights. That would be nice because sometimes you will have lights the you could with out complex GI calculation and leave it to the hero lights in the scene. Anyways this is a long confusing question but if any of you guys come from Brazil R/S pipeline and know how to make it feel more comfortable with some quick solutions on how pull off photo real with some cool cheats drop me a response,

Cheers

[Burnsyman9000]

I know what you mean Nathan, I always considered being able to disable 2nd bouce or even all GI from selected lights was a key method for making renders fast and efficient, it seems frustrating not to have the Option in Vray, maybe something for the wishlist.

[arcfx]

good idea

good idea, I will post it in the wish list,
Cheers

[cpnichols]

You can turn off the secondary bounces. Simply select "none" as an option.

[arcfx]

but...

but you can't do it for selected lights

[ene.xis]

i don t see the point of this...

u could concentrate on a all lot of areas to keep ur rendertimes down, and would then realize turnig gi for a selected light wasn t needed.

nevertheless,
i think that it can be done by tricking gi...just precalculate ur gi solution only with ur "hero" lights. save it. turn on the 2nd lights and render using the saved gi...

ps. if u need help with ur rendertimes or any othr subject just post it...i m sure u ll get all the help u need to get it going!

[percydaman]

I disagree. I think removing selected lights from being included in GI, would be incredibly helpful. It might not be something I would use alot, as I render alot of specific passes anyways, but not everyone needs that.

[Paul Oblomov]

Does VRayLight produce GI light ? I always thought it makes just direct lighting.
Only if you "bake" it in irrmap, then it became GI light.

[arcfx]

thanks

Thank you percydaman for understanding.

I use all the renderers out there for 3dsMax and I find this a great option to have less GI less render times. I know Vray works much different than other renderers out there but this is a fact for any renderer, less GI to calculate fast render times.

Lets say I have 100 light in the back and I have a hero light that is an area and I'm rendering in film res like 2k or 4k. this is when rendering 100 GI lights is a pain and could do with out.

anyways every other renderer has it so why not Vray,
Cheers

[ngrava]

I have a question: Why would you need 100 lights in your scene?

The reason I ask is that a common problem that I see with people who come from other, usually non GI renderers, is that they tend to think of lighting from a "Painting with Light" perspective. This is where you start out completely dark and start adding lights to very discreet areas of the scene in order to make things pop out from each other and create a more dynamic range of shading in the scene. The over-all effect in a non-GI renderer is really nice but in a GI renderer, it can look really bad, add unnecessary calculations and in general counteract the whole look of GI in the first place. The problem is that GI should be doing the dynamics for you. Essentially, a GI renderer is performing a simulation and you need to learn how to work within the simulation.

For character work I usually start out with a background color. 50% grey or sometimes a gradient. Then add a key light. Sometimes, depending on the scene geometry, thats all I need. Basically, I try not to use to many lights in the scene because every one adds time the render. A lot of times I'll even add a bounce card instead of another light on the opposite side. But a lot of times the background color takes case of the usual fill lighting that you would normally have to build yourself without GI.

Now, this might not be the case for you at all. Maybe you already know all this. Maybe, you are using 100 lights to simulate track lighting in an Arch/Vis model. In that case, you can still cut down on the number of lights. Here's a trick:
in Max, you can use a texture map on the light that is basically a black image with white spots on it. When you put this on a large light, the light only shows through where the texture is white giving the illusion of multiple lights.
But, maybe that's not it either. Maybe you just need to use a lot of lights and you just want to see what it looks like. In that case, I would use Light Cache (I use this because it is more intelligent about bouncing that QMC), with it's subdivisions set to something like 200 to 500 and an irradience map set for "Low". That should give you a fairly quick render. In addition, you can lower the hemisphere subdivisions (in the irradience map settings) to 20 or so from the default of 50. Remember that if you are using Reflection and/or refraction interpolation in any of your materials, that's going in effect your irradience map too. So, if your just doing stills, use low settings like -3 to -2 for the rate. Increasing the "Max" value will actually add more passes to the irradience map at times.
And lastly, raising your Global QMC threshold can have a big impact on your scene too. This controls the overall adaptiveness of the renderer. Lower numbers will make it less adaptive, thus making it use it's highest settings more frequently. Higher numbers will use the lower setting more often. One way of understanding this is that every now and then you'll see minimum and maximum rates for things like IR Map, interpolation and sampling in the panels. Vray can be told to intelligently concentrate on the details in your scene. The global QMC threshold is a setting of how intelligent it will be about that. How often it uses minimum number of samples and how often it uses the maximum number of samples. (those are the little -3 to -1 setting).
I know there are a lot of setting in Vray but if you stick to the irradience map presets, they will actually work for you just fine. Vlado knew what he was doing when he created them. A lot of time when rendering animation for commercials here at work, we just use a few lights, background color, Light cache (set for 700 subdivs) and irradience map set to "medium animation" and it works great without touching anything else. All of this has been learned over the corse of using Vray for about 3 years now.