sRGB speed problem

[Devin Johnston]

I never noticed this before but when using the vray VFB and having the sRGB color space engaged it really slows down rendering. When it's on my renderings take about 75% longer, this is with the same GI & AA settings the only thing that's different is the color mapping. Does anyone know why this happens?

[Chris MacDonald]

It shouldn't, as it isn't affecting the render at all - only the frame buffer/image output. Can't say I've ever noticed it, but then again I've always had it turned on so have nothing to compare it to.

[ARTE DELLA VITA]

lol, i see you asked this question on chaosgroups forum also and got some good answer but just for the benefit of others here, it was not the srgb button on the vray frame buffer slowing the renders down it was having "dont affect colors on". please read this thread before you guys gett confused.

 

http://www.chaosgroup.com/forums/vbulletin/showthread.php?71652-sRGB-mode&highlight=srgb

[Devin Johnston]

I'm still confused.

[ARTE DELLA VITA]

I'm still confused.

 

really? from what was said i thought you got it by now, the whole issue i see though is with gamma and linear workflow, i will make a video on this for you and send you the link, i think just explaining without pictures and demonstration is not enough, a picture is worth a thousand words so just let me know if you me to go ahead and make a youtube vid on my blog for you Devin. I also notice that on chaosgroups forum some people try to give hard and complicated explanations sometimes for very simple things which confuses alot of people sometimes and people are then afraid to ask what they mean and not look foolish but i have bought many tutorials and i have a stock libray packed with help and advice so i can help with the simple things sometimes

[Devin Johnston]

Thanks shawn, I understand that Vray is calculating the scene differently and that's why it's slowing down, I guess I'm not so much confused as I am irritated. My tests haven't shown any appreciable difference in the image quality of a scene rendered with and without these settings turned on. I'm sure there are instances where these settings are needed especially if there is a lot of excess noise generated. It just irritates me that such a simple thing can cause such a massive increase in render time.

[ARTE DELLA VITA]

well i ran some tests but with a small plane and tea pot with other small geometry to see how this affects my scene and there are slight changes but not much in terms of time, 2mrw i will run some tests with a more complex scene, there are occasions though when i had to work this way and have the srgb button on and the gamma 2,2 and dont affect colors on when i had some very small artifacts the were really annoying me it fixed the issue and i was not even paying attention to render times because they were not really much different. but i will dig for that scene and run some tests on it to see for myself the effects of using one option over another and post the result for anyone who wants to have a look.

[Devin Johnston]

The scene I was testing it on was an interior with quite a few IES lights and an HDRI for exterior lighting.

[ARTE DELLA VITA]

hmmm, ies lights, looks nice but a killer on render times, i will also use that setup in my tests

[ARTE DELLA VITA]

well here is what happened, a made a few tests and there is no difference between having the don't affect colors button ticked or unticked even with a few ies lights in an interior scene. I will try an even bigger scene 2mrw with higher settings but for now there is no difference in render time

[Devin Johnston]

It must be something specific to my setup then because Chaos said they weren't able to replicate it either. I sent them my scene this morning and I'll let you know if and when they get back to me. I am using an older version of Vray 2.1 so maybe it's a bug that they've already fixed, we'll see.

[ARTE DELLA VITA]

ok no problem

[Devin Johnston]

Ok I got a response from Chaos, here it is:

 

"Thank you for sending us the files. We reproduced the issue and discussed it with the developers.

According to them there was a change in the sampling attitude requested by users. We need to over-thing that again. For now that is the way it works, but we are still improving it.

The effect can only be reproducible with Adaptive DMC sampler and Sub-pixel mapping enabled at the moment."

[ARTE DELLA VITA]

hmmm, i see, i will also try to reproduce it this way, thanks for keeping us update devin

[artmaknev]

The VFB does slow down the system a bit, I noticed that as well, when I switch to maxFB it closes fast, but VFB takes a few seconds to close after, not sure why.