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reflections are killing rendering time


d7man2000
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I have a basic scene with 3 buildings and glass in each building. When I render it takes long time like crazy. I used Mental Ray and it didn't take that long.

Please tell me what am I supposed to do. I want to create an animation.

I have 4 computers to do this. Even with distributed rendering it takes a long time to calculate each frame.

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vray is super slow in comparison to Mental Ray.

for exterior scenes with buildings that have reflective windows , Mental Ray is very fast , with Vray I am waiting and waiting, I reduced the settings but it is too slow.

I thought I would not miss Mental Ray but MR is a pretty powerful program, I can't get used to Vray, I got decent stuff done with Mental Ray, less settings, more efficient.

If anyone knows how to get a short render time please let me know.

I reduced the subdiv, refl. depth, it is still too slow.

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I'm with Travis. If you don't show us some test renders and let us know what settings you're using and/or how you have made your materials, there is no way of knowing what steps to take to speed up your renders. Like mental ray, there are a dosen different directions to go to get quicker renders. You first need to figure out what is actually making it take so long before you change every setting.

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this project I am working on is a proposal so I am not supposed to show it.

I did tests of both Vray and Mental Ray and I am gonna stick with Mental Ray.

It does Global Illumination very nicely, I can't tell a difference really. I cranked up AntiAliasing and FInal Gather and I use 1 directional light, 1 Sunlight and I am happy with a result. I am more efficient with 2 computers than 6 with Vray. I get Final Gather calculation of 250 quality quickly and rendering is quick too at 720x500.

One thing that pissed me off with Vray(with Mental too but less) are blotches,

you have to crank up the settings really high or use VRmap where you render multiple times but it takes time.

Anyway, in this case Mental Ray wins.

I have to render about 2000 frames of exterior buildings with reflection and refraction.

I will post settings soon, I have to finish when machines finish renderings, it should be today. I get something like 30 frames per 10 minutes of rendering.

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Wow. Okay, you have some settings here that are killing you. You need to go learn more about Vray settings before straying too far from the defaults.

 

The antialias max at 3 is probably unnecessary, the QMC Sampler settings are WAY too high, and the glass is pretty strange, I'm not sure what effect you are going for but maybe you could use the egz materials - go to http://vray.info and get the "Beta Collection" under Materials on the left. Change all your settings back to defaults and start doing some Vray tutorials. If you watch Chris Nichols DVDs (go to the Shop link above on this page) you'll get a lot on sampling rates and QMC settings.

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Change a few of these settings and let us know what you get.

 

Image Sampler:

Max rate: 2 - and check Object outline and Normals

 

Irradiance Map:

For an animation change it to the Medium-Animation preset. And uncheck Show calc phase for netrendering, it just takes time and memory.

 

QMC Sampler:

Adaptive amount - .95

Noise Thresh - .005

Min Samples - 4

Global subd mult - 1

(These would be different for a still than for an animation)

 

Material:

This looks fine to me, but you should know that the Reflection Interpolation doesn't really work well for sharp reflections and you don't have it checked active anyway. So I recommend you keep it off.

 

Raytracer: VRay ignores this as it uses it's own raytracer.

 

Other: make sure your sun casts VRay shadows and that all your materials are VRay materials.

 

Animation: If nothing in your scene moves but the camera, I would highly recommend using the LightCache. Also, look into creating a saved GI solution for the animation and then netrendering the frames.

 

Good luck.

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I have to disagree with both suggestions:

I had the settings you suggested and they will slow down render even further in QMC Sampler. The higher the faster render. I tried it many times.

As for Max Rate set to 3, I can't use Max Rate set to 2 because Antialiasing is bad. 3 only works.

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I tried the settings and it still too slow. Max Rate set to 2 shows broken lines, only with Max Rate set to 3, it looks ok.

the quality is not that better.

I will try using Lightcache but I had a problem using it with distributed rendering, it just crashes the server and I think it works only on one computer.

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I seriously doubt you are going to improve upon the 20 sec/frame you are getting with Mentalray, I mean if those frames are actually acceptable, have you put them together yet to see if there is any flickering, thats going to be the main concern...

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c'mon vray gurus, there must an easy way to do this, I liked Lightscape approach with radiosity, you run once a solution and you can render from whatever, render time=1second, now we're talking.

it's fine to get a nice render of an image that takes 12 hours to render but it is not practical in a real life situtation, your boss doesn't care what's photons or light cache, if something looks bad and takes too long, it doesn't suggest that guy knows what he's doing.

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I honestly don't understand your delema, why is it so important to do this with vray, if your getting what you want from mentalray, by the way does your mentalray animation flicker, I can't imagine your getting flicker free GI at 20 seconds per frame, but if its true maybe I'll take mentalray for a spin...

 

And the answer is no, you'll never get those kind of render times with vray with settings high enough to be flicker free, its the nature of the beast, unless you've got a couple hundred computers...

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yes the little flickering won't go away untill you pump the settings way up, on any render engine, that's where the long render times come from, by the way what are your material settings, you have a map in your reflection slot, what is it?

 

And you do have an hdri map in your environment reflections...

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Maybe you should set density based (splotch free:) ) sample lookup in IR map settings...

also set distance treshold to 0.2-0.3 or maybe even more...

That would slow things even more but should probably remove flicker...

 

Then try with 8 min samples in QMC sampler.

You are using 80 and secondary engine is QMC.

My guess is that this is slowing the hell of your renders.

 

The higher the faster goes for the noise treshold in QMC,

but that is giving you flickering when set on 1.0.

Try decrease it to at least 0.1.

 

 

Also try to reduce max rate in image sampler to 2 and check outline and normals box. This is good for any still so it must be good for animation.

For a better result you could also decrease treshold to 0.05 or less...

3 is good but slow.

 

I hope this helps.

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