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NDoubleV
06-09-2012, 03:23 AM
I tried some unbias render - maxwell and indigo . it is too slow for rendering. maybe , the result can get 99% realistic but 95% in bias render as result on mental ray and vray is similar. i have not yet try render man. Why do they increase speed for unbias rendering?

Darkmalan
06-09-2012, 12:06 PM
The reason why unbiased rendering engines take a long time is because they sample every light path within a scene. Biased rendering engines such as mental ray allow the user to roughly define how many times a photon can bounce or how many light rays are sampled and then the rest of the samples within the scene are approximated from the samples that were actually calculated.

Biased rendering engines are very fast for this reason because they approximate samples but this can cause errors to occur within a scene if not enough samples are calculated and too many are approximated. Whereas the results of an unbiased rendering engine will be flawless in almost every situation.

The main difference is that biased rendering engines are fast to render but take a long time to set up the rendering eg setting up photon mapping, light caching irradiance mapping. Unbiased rendering engines do not need any of these settings but do take a long time to render.

So unless you are an expert with biased rendering engines, unbiased rendering engines will take about the same production time up you just spend your time differently. Either tweaking approximation values rendering and re-rendering constantly, or just hit render once let it render overnight and have the result in the morning with little effort... just depends on how you want to spend your time really.

matthewspencer
06-11-2012, 01:56 PM
I agree with everything said by Darkmalan. Really, even though the actual render time for something like Maxwell is quite slow, it is true that you save huge amounts of time in the set up. There are also quite a lot of tips to get faster renders out of unbiased renders, that many people don't take advantage of. (E.g. don't use pure white materials, use real-world scale for objects, don't use volumetric glass, don't use one-sided subsurface scattering)

If possible I think it's good to have some combo of renderers at your disposal. Pair VRay with Maxwell or C4D Advanced Render + Luxrender. Versatility is great; you can make quick and dirty test renders and then set up overnight unbiased batch renders for your serious stuff.

Oh and if possible, get a beastly workstation ;)

MikeBracken
06-11-2012, 03:29 PM
Just wanted to mention that with experience comes much faster setup times. In archvis one guy here can setup complex scenes in a couple hours. When working with Mray,Vray, etc, you just get to know what to expect, so there arent hours of tweeking for GI, reflections, etc.

Regards,
Mike

matthewspencer
06-11-2012, 05:56 PM
Mike has a very good point. Product design studios who work in VRay don't even need to change settings render-to-render, they can just swap out the object on the "stage."

I guess it really would depend on the needs of your workflow. If you work in a studio that needs to output many renders all week long, unbiased rendering is probably not wise. If you mainly deliver work to clients in large infrequent presentations, an unbiased renderer could give your work real depth.

Personally, once I turned to Maxwell, I haven't looked back since. But if I hadn't bothered keeping VRay on my machine, I'd be at a real disadvantage if a client needed finished renders 2 hrs from now.

NDoubleV
06-12-2012, 03:04 AM
thank all. ur experience is valuable. at now, i just only use Mental ray for all jobs but it have many limited. I want try one more to provide my job. these are many programs at now, i dont know how to start. Vray and Mental ray is similar method, that is my think :shrug:
what do you think 3delight render engine?

matthewspencer
06-12-2012, 02:41 PM
Even though I'm a huge fan of Maxwell, and use it for all my work, I'd probably encourage VRay in your case, since you're already coming from mental ray. It has a larger user base than any of the unbiased renderers, and integrates well with 3DS Max, if you're already familiar with the interface.

IMHO, steer clear of niche software like 3delight that have a really small community. Learning new software is when you need assistance the most! An empty forum doesn't help.

If you still feel like getting into unbiased rendering, maybe give LuxRender a try? It's free + open source so you have nothing to lose.

CHRiTTeR
06-21-2012, 04:49 PM
I dont agree that biased renderers take much longer to setup, though.
While an unbiased renderer does take quite some extra rendertime to get clean results.

Darkmalan
06-21-2012, 05:20 PM
Its like i said though, if you have a lot of experience using biased rendering engines then you will be fast at setting up. If you have little experience with unbiased renderes then you will get results but after hours of tweaking. It also depends on how complex the scene is as well.

CHRiTTeR
06-21-2012, 05:44 PM
Hours of tweaking is exagerated, the only difference is you need to know the amount of samples to use. Thats it. Everything else is the same.

And if you use adaptive sampling you dont even need to setup the amount of samples it will be done automaticly for you. You only need to set the treshold value and you're done.

matthewspencer
06-21-2012, 06:12 PM
Hours of tweaking is exagerated, the only difference is you need to know the amount of samples to use. Thats it. Everything else is the same.

Ehhh...no

GI reflection bounces, GI sampling algorithm, GI sampling accuracy, oversampling, caustics settings, AO settings if desired, refraction bounces, shadow density. These are just a few common biased rendering areas that a person has to tweak, which do not exist in unbiased renderers. Add to that: scene lights with arbitrary intensity settings, materials driven by arbitrary parameters, etc. Then in the case of VRay add 500 more steps ;) (only joking)

Again, as stated by Darkmalan, setup matters less and less as a person becomes more and more experienced in a particular software package. However the very nature of tweaking compartmentalized, meaningless rendering "values" is just inherently more intensive than setting up your scene with (e.g.) some 100 watt lamps, automatic lighting with a real world sky, and using a 35mm camera to make an image. Real physics, real-world values.

But if I need 10 images in the next 2 hours? Bias all the way.

CHRiTTeR
06-21-2012, 06:51 PM
Ehhh...no

GI reflection bounces, GI sampling algorithm, GI sampling accuracy, oversampling, caustics settings, AO settings if desired, refraction bounces, shadow density. These are just a few common biased rendering areas that a person has to tweak, which do not exist in unbiased renderers. Add to that: scene lights with arbitrary intensity settings, materials driven by arbitrary parameters, etc. Then in the case of VRay add 500 more steps ;) (only joking)

Again, as stated by Darkmalan, setup matters less and less as a person becomes more and more experienced in a particular software package. However the very nature of tweaking compartmentalized, meaningless rendering "values" is just inherently more intensive than setting up your scene with (e.g.) some 100 watt lamps, automatic lighting with a real world sky, and using a 35mm camera to make an image. Real physics, real-world values.

But if I need 10 images in the next 2 hours? Bias all the way.

Again greatly exagerating. Those are hardly hours of work.

And actually vray removes quite some steps if you use full adaptive sampling

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