Rendering Speed

[Donfarese]

A Clamp for the GI like Octane has might really help cleanup. In Octane that one setting really helps speed tremendously. I don't really see a down side to Gi Clamp, can you explain some possibilities? I am working on putting together another scene, I am so busy right now and it takes some time to do both scenes in each render engine. Wondering if your team has come up with anything yet, would absolutely love to see vray gpu render faster than octane, or as fast. In all my scenes so far which has been 4, Octane has been much faster.

Also is there a way to get Lens effects to be interactive with RT like it is with octane, I see this as a huge advantage of working on a scene. Also Lens effects sometimes shows at the end of the render, but sometimes it doesn't.

[savage309]

We have "max ray intensity" which helps removing fireflies. It is in the global switches, see if that helps for you.

We have simplified the scene you have send. We had, since the original ones had gamma, glossiness, GI depth, lights (power, color, and even number) different. Renders make difference between light texture and a light, and this leads to different results.

This is not a good benchmark yet, it lacks many stuff - complex materials (Ward/GGX?, layered, SSS), procedurals, UDIMs, complex geo (and displacement?), and so on. Fair comparison is not easy to do. The scene now is simple, and there are still differences in the light which are biasing the results.

Also, V-Ray builds its GPU kernels on-the-fly. This has many advantages like - the newer your driver is, the faster V-Ray will be. But may take some time more before render start. This time is included in the render time. We cache those kernels and if you render a scene again that does not require new kernel build, V-Ray will appear faster (no extra time will be added).

Having many fast or feature-complete GPU renders is great - both for the users and the render engines. We get better, you have choices. It is great to have feedback (and scenes to profile & debug ).

Images comparing different number of GI bounces, same amount of time, 1 Rect Light + Diffuse Mtl. Just for fun, there is also one with LC that was rendered for half of the time the others had. Tests were done using Titan X, driver 353.06 and V-Ray 3.20.02.

[savage309]

The forum allows 5 images per post, so here are some more. We may try to create more real-world comparisons in the future, too.

[Donfarese]

Looks like we are using the same hardware, I too am using a Titan X, driver 353.06 and V-Ray 3.20.02. Seems Vray still has some more noise, would like to see you test with lights, & IES, that's where it seams I am getting a lot of noise from vray. Loving what you have done with vray, and I think with some tweaking it will be astonishing GPU renderer. For right now on all the more complex scenes I am using, it does seem to be quite behind in removing noise. I have a scene I'm putting together for you guys to test from a client, it's not that complex, but might be better for test.

[Donfarese]

One thing I noticed with the LC, it is great and super fast, but from lights it leaves a lot of Speckled noise on object highlights. Doesn't happen with the BR + BR. what can I do to resolve this?

[savage309]

One thing I noticed with the LC, it is great and super fast, but from lights it leaves a lot of Speckled noise on object highlights. Doesn't happen with the BR + BR. what can I do to resolve this?

The support guys are much more familiar with that, so it will be best to send them scene for investigation. Also, you can check the docs for the Light Cache http://docs.chaosgroup.com/display/VRAY3/Light+cache. Probably you can try to switch the "Use light cache for glossy rays" option to see if that helps.

[Donfarese]

Okay I actually found it has a lot to do with the "Max paths/Pixel" and "Max. Noise" RT Settings working together. you actually don't even have to touch the LC Settings. With the right RT settings of those two, they can be pretty much universal, and I cut some of my renders by 1/4th.

[super gnu]

yes you have to use the max noise setting, if you have it set to 0, it refines all the pixels continually. if you set it to a nice value ( 0.006 for example) it will quickly stop working on the easy areas, and concentrate on the difficult bits. the max paths/pixel and max time settings are less useful generally.

[Donfarese]

yes you have to use the max noise setting, if you have it set to 0, it refines all the pixels continually. if you set it to a nice value ( 0.006 for example) it will quickly stop working on the easy areas, and concentrate on the difficult bits. the max paths/pixel and max time settings are less useful generally.

You are correct sir. The max paths/pixel are really important for animation which is what we are doing, combined with the max noise of course. The max time is not nearly as useful, but an awesome feature to have.

[super gnu]

im wondering why max paths/pixel is useful for animation? surely you want the pixels to have a uniform noise threshold, and dont care how many paths each pixel needs to get there? i guess im missing something!

[Donfarese]

im wondering why max paths/pixel is useful for animation? surely you want the pixels to have a uniform noise threshold, and dont care how many paths each pixel needs to get there? i guess im missing something!

You set the max noise to .004, that will give you a clean render for noise, and once the easier areas reach that number the renderer then focuses on the more difficult areas this giving you a really nice speed boost and cleaning noise in hard areas. If you have max paths/pixels set to 0 the renderer will just continue to render pretty much wasting time for clarity you will not really notice. Setting the max paths/pixels to say 10000. Will give you a more accurate time per frame, will render faster, and will keep the renders more consistent. Unless I'm mistaken.

[super gnu]

as far as i understood it, if you set the noise threshold to 0.006, then once a pixel reaches that threshold, vray will stop working on it and focus one the ones that still need it. therefore progressively working on less and less of the image, and speeding up.

once all the pixels are at the noise threshold, it stops.

i cant see how limiting the rays per pixel changes this. if its more rays than the number you need to reach the threshold, it wont affect anything, and if its less, you will end up with noise in your difficult to clear areas, since it will stop shooting rays for those pixels before they are clean.

i dont think you need anything more than the noise threshold, or the time limit if you need something absolutely finished in a certain time. may rays per pixel is the odd one out for me, i still dont see its real-world use.

[Donfarese]

as far as i understood it, if you set the noise threshold to 0.006, then once a pixel reaches that threshold, vray will stop working on it and focus one the ones that still need it. therefore progressively working on less and less of the image, and speeding up.

once all the pixels are at the noise threshold, it stops.

i cant see how limiting the rays per pixel changes this. if its more rays than the number you need to reach the threshold, it wont affect anything, and if its less, you will end up with noise in your difficult to clear areas, since it will stop shooting rays for those pixels before they are clean.

i dont think you need anything more than the noise threshold, or the time limit if you need something absolutely finished in a certain time. may rays per pixel is the odd one out for me, i still dont see its real-world use.

I'll Give you an example.

On a scene I'm working on:

Max. Noise .005, Max Paths/Pixels 40000 = rendertime 1min 50sec

Max. Noise .005, Max Paths/Pixels 0 (so disabled) = rendertime 14min 49sec (only because I got tired of waiting and stopped the render)

Out of both of those you could not tell a difference at ALL.

[super gnu]

this, to me, just means you can get away with a higher noise threshold, since its never reaching 0.005 with the max paths/pixel stopping it in the difficult areas before it gets close to the final noise threshold.


did you compare both images after the same amount of time? i.e. how does the image with no paths/pixel limit look after 1 min 50 secs?

[vlado]

V-Ray's adaptive algorithm is generally somewhat conservative and may continue sampling some pixels way beyond what they really need. It's on the "to do" list to try to improve that. But for this reason, I would not recommend using 0 max paths per pixel - best to always put some cap on that.

Best regards,
Vlado