Vray 3,3 render test comparison

[BBHead]

Hi All,

I am writing this post to try and achieve two things. The first is hopefully help myself and others with understanding the new sampling in Vray 3,3. Second to confirm what I'm saying is actually correct
I wanted to see what was the optimal setup to achieve highest quality results with optimized render times. The reason I done was after listening to CG Garage Podcast with Lele which was great by the way! The new render method in 3,3 was spoken about at length so I wanted to see what it could do and maybe try and understand it a little.

I have attached am image which is a comparison of the renders with and without use of local subdivs. It's a basic scene which came with one of the lessons for a Grant Warwick course I'm doing at the moment. The render set up was as follows:

640*480
min sub 1
max sub 8
noise threshold .005
No GI

So without use of local subdivs the scene rendered very quickly compared to render with local subdivs in use but there was definitely more noise and the AA was by far doing the most work as seen in sample rate pass.

Then I tried a high quality render without local subdivs to try and achieve better/same as render on right. Settings:

640*480
min sub 1
max sub 32
noise threshold .001
No GI

Quality was the same now at least in color render but still some noise in the reflection pass and now with a much longer render than one on right side(using local subdivs)

I would like to know if what I seeing here is what you would expect?
I would also like to know, is it right to expect best results using local subdivs?

Am I right in saying the new sampling is great for getting results quickly without having to play around with settings but when looking for best quality/time one still needs to tweak local subdivs?

Michael

[Alex_M]

I'm not sure if I'm knowledgeable enough to answer your question about whether using local subdivs is better if done properly but I would take your "noisy" render (the one that took 7,9s) any time over the other one that took 5x more time to render. When you factor in the great noise to speed ratio, the faster image here is the winner. Heck, I don't even consider your "noisy" picture noisy. To me some very fine noise is ok as it adds a bit of believability (real-world cameras ALWAYS produce noise to some extent). If you really need impeccable silky-smooth render, I would run a light noise reduction filter and it will be as good as the other just 5x quicker.

Are you sure you're not viewing the Reflections render element with sRGB turned on? I'm pretty sure this is the reason for the noise in it. If you turn off sRGB you shouldn't see that much noise in the Reflections element. Render elements should always be saved in linear space anyways and that's how they are being composed so the correct way should be to view them in linear space (turning off the sRGB button).

By the way, did I say that I LOVE the new sampling method in SP3? It really kicks @ss and it's my preferred way of work now. After using it a bit I really realized how tired I was doing things the old way, setting up subdivs for each and every light and material. If any other company were to release such an awesome update with all that great new features and bug fixes, it would have easily been branded as a new release. You guys rock!

[padre.ayuso]

That's an interesting point that Alex_M brings up, I had no idea about this sRGB making noise in reflections. Now, in terms of photographic noise, he's right, but as a photographer, I also attempt to achieve smooth photos and noisy photos are not necessarily a good thing to have, but you are right, perfection is basically unattainable, so making your renderings less than perfect with some noise will definitely add realism and sure enough, "perfectionism".

Just a point for Michael, I answered your post on Grant's website. I think if you take all of the answers around you will get a good idea of what level you want to achieve. Additionally, if you want to reduce that noise, you increase Min Subdivisions, and increase Max Subdivisions. The problem you are facing is that VRay is not using enough Samples and thus creates noise. Give it a try, there will be an acceptable level somewhere in there. Additionally, I had a scene where I decreased the Min Shading Rate as I did not need to clean up my GI solution (as I was using IR and not BF and it was clean enough with 2 Min Shading Rate) and then increased the Min Subdivision to 10 and my Max Subdivisions I think I had it up to 100, the whole rendering cleaned up, no "noise" and it rendered under 1 hour at 3K. Had I had that knowledge before I sent it to render, it would have taken me 10 mins of setting up and test renders. Now that I know, I can play with those parameters and achieve what I need with just a few clicks. And as I said earlier, I'd not have been able to work it out without Grant's knowledge, so keep on going and use the workflow best suited for your needs.

[vlado]

Kind of hard to say without looking at the rest of you settings, f.e. I don't know if you are using the new adaptive or not; your color mapping settings might have some effect too. Best to post your scene as well.

Best regards,
Vlado

[BBHead]

some good feedback guys.

To Alex M - I hear what your saying about render quality and time trade off.I agree that you can get good results quickly but In my opinion for a render that will be used by a client that level of noise in some cases would be unacceptable. There are obviously several ways in which you can render an image to achieve acceptable results but of course it then becomes a question of what gets you there the quickest. It just seems to me that when you leave the AA to clean up an image it will in some cases take longer and might not even get you there especially when going for super clean results. I am a student of Grant Warwick and I feel his logic on render settings still apply's here when looking for a high quality render. Meaning using local subdivs and reducing the work load on the AA to achieve a balance between the two while finding an acceptable noise threshold number. Giving a very clean render quicker.

To Vlado - I am using the new adaptive. On the color mapping I have tried a few different settings but still seeing better results with local subdivs being used. Is there anything more specific you can point to with this. I can't send a file at the moment as not near my workstation for a few days.

Cheers

Michael

[vlado]

Ok, it would be best to continue the discussion when we have the scene then

Best regards,
Vlado