"real" ambient occlusion

[atrask@hksinc.com]

Can we get an ambient occlusion render element pass that gives us exactly what we get by checking "Amb. occlusion" under the GI tab in the render dialog?

I realize the current solution for comping an AO pass is the dirtmap trick using the VrayExtraTex render element. But that's a bit hacky, for instance there shouldn't be ambient occlusion in direct light which the VrayExtraTex doesn't account for.

Anyway, having this would help bump up Vray's caliber imo.

Thanks!

[vlado]

I don't really like using ambient occlusion for GI to be honest. If you want your scene to look like the space hasn't been dusted for a while, then I guess it's fine, but in general it makes the images less realistic.

Other than that, you can use an AO pass with VRayDirt and apply it only to the GI render element before comping the direct lighting on top.

Best regards,
Vlado

[Art48]

I have to kind of agree with atrask here. We're doing Product Viz mainly and we use AO (ExtraTex that is) 100% of times. While we are used to the workflow of painting in AO manually (meaning masking the ExtraTex element where appropriate) it would still be of help to have the "GI AO" if you will as base since we will never paint in AO where much direct lighting hits. Just for your information Vlado, I think people may use AO way more than you think. While yes it is not neccassarily realistic, it is a huge help in making details pop and in the end it is all about making an image more readable to the viewer. AO helps - so we use it very frequently. Also we don't do comping the layers but we start with the beauty pass and go from there. Photoshop just lacks too much to do the "usual" workflow of comping elements like you may do in Nuke.

edit: To elaborate - we are also often rendering huge images (25k px) via online render farms and they don't support rendering without the VFB so we often run into cases where we cannot have all render elements neccassary for proper compositing because if would blow up the RAM.

[Micha]

I use AO for adding details to technical metal objects like dental implantats with fine threads. Simple multiplied over the beauty pass in Photoshop. Not everywhere at the image, only there needed. An automatic AO pass would be a time saver.

[kosso_olli]

In my opinion AO should not be there anymore in any renderer. I mean, why have something that ancient when we have fast GI methods these days? It is a dirty cheap trick, and you can see that everywhere where it is used. Man, I had so many fights over this crap in my years.
Multiplied over the beauty pass. I get shivers when I just read that... That is one of the reasons why I just "forget" to hand the AO over to the retouchers...

[Micha]

If my client ask for it and need it for technical illustration and 100 % photo real isn't wished, why should I ignore him? And he pays not bad. And result was perfect.

Where is the artists freedom? Right, AO as cheap GI looks bad often, but for postwork it's a good tool. Sounds you think AO should be canceled from the feature list.

[Art48]

In my opinion AO should not be there anymore in any renderer. I mean, why have something that ancient when we have fast GI methods these days? It is a dirty cheap trick, and you can see that everywhere where it is used. Man, I had so many fights over this crap in my years.
Multiplied over the beauty pass. I get shivers when I just read that... That is one of the reasons why I just "forget" to hand the AO over to the retouchers...

In the end you have to make an image that the client is satisfied with or even love it! If that means taking an AO pass to make some details in crevices pop so be it! I am mot talking about multiplying a 2 meter radius AO over everything. Use it with a bit of knowing what you want to achieve and not overdone and it makes stuff pop.

[kosso_olli]

Sounds you think AO should be canceled from the feature list.

If there was a poll, I would definitely vote for removing AO from V-Ray. From any renderer in fact. It is fakery from a decade ago. Problem is that clients got used to that "look" from the past, thats why they demand it.

[Art48]

Remove it? Do you mean removing the VRayExtraTex or rather the VRayDirt? Would make literally zero sense. If you talk about the AO settings in the GI Tab - it could propably be removed but then again as long as it is disabled by default - who cares. It would mean less clutter in the UI though And I know Vlado aims for that (successfully with the beginner/advanced/pro settings). I on the other hand am all in for even more clutter! :P

[instinct]

If there was a poll, I would definitely vote for removing AO from V-Ray. From any renderer in fact. It is fakery from a decade ago. Problem is that clients got used to that "look" from the past, thats why they demand it.

While i agree that AO should never ever used as a GI replacement and i am also pretty sure in most cases it is used wrongly even when used as that (e.g. applying it in direct light areas being the main offender) i still think there are very valid use cases
for NPR and for artistic post things like emphasizing details. That is not "fakery" it simply serves a different purpose than GI.

That being said an ExtraTex element serves fine for that.

Cheers,
Thorsten

[Syclone1]

If there was a poll, I would definitely vote for removing AO from V-Ray. From any renderer in fact. It is fakery from a decade ago. Problem is that clients got used to that "look" from the past, thats why they demand it.

Not every artist is looking to produce 100% photo realistic renderings, we are called artists for a reason and a vast majority of even Arch-Viz renderings are "Artist Impression" because you are creating a scene of what you think the end result of the plans you are working on will look like when built. If the client and/or artist like using AO then what is the harm in it, yes it is not "Photo real" but you have to ask yourself is someone else's use of it really affecting you in ways other than your personal opinion? If you don't like it then don't use it, and if there are images using it then just don't look at them if its that offending to your eyes. Sorry even though I don't use it myself I don't see a reason to kill it off because you don't like it, Im not trying to start a huge debate but Im just trying to point out both sides of the issue and these are just my thoughts.

[kosso_olli]

Thing is I have to use it because post guys are demanding it. Mostly it goes like this:

Post guy: "Can I have the AO please, I need it!".
Me: "Do you know how to use it?"
Post guy: "Yeah, I just multiply it on top, right?"
Me: "Get out!"

Thorsten, nice to see you! How is business?
Sure, AO has its advantages at big houses like Macke. I remember people there used to know how to use it correctly, so it never looked odd. But believe me, I have seen so many images with wrongly applied AO that I can became tired of preaching the right way.

[Art48]

Thing is I have to use it because post guys are demanding it. Mostly it goes like this:

Post guy: "Can I have the AO please, I need it!".
Me: "Do you know how to use it?"
Post guy: "Yeah, I just multiply it on top, right?"
Me: "Get out!"

Thorsten, nice to see you! How is business?
Sure, AO has its advantages at big houses like Macke. I remember people there used to know how to use it correctly, so it never looked odd. But believe me, I have seen so many images with wrongly applied AO that I can became tired of preaching the right way.

What would be the right way to use it (apart from maybe multiplying with the GI pass if you do the real compositing stuff)? Personally I start with multiply mode, but mask it black completely, then paint it in where I think it fits and looks good, sparing parts in direct light and so on. I've heard people using the AO as a mask to levels adjustment layers and all sorts of stuff but the (nuanced) mutliply way of doing things seems fitting to me. I really don't want to step on anyones toes and I am always willing to learn so could you point out what the "right" way to use it would be in your opinion?

[instinct]

What would be the right way to use it (apart from maybe multiplying with the GI pass if you do the real compositing stuff)? Personally I start with multiply mode, but mask it black completely, then paint it in where I think it fits and looks good, sparing parts in direct light and so on. I've heard people using the AO as a mask to levels adjustment layers and all sorts of stuff but the (nuanced) mutliply way of doing things seems fitting to me. I really don't want to step on anyones toes and I am always willing to learn so could you point out what the "right" way to use it would be in your opinion?

To be honest i don't think there is a "right" way if you are using it as a GI replacement heh. The main point often missed and leading to the issues Olli mentioned is applying it to the image all over rather than just to indirectly lit parts (=no direct light hitting).

I would step back from using it to contribute to lighting in any way though. I'd say it is an artistic tool you can use to bring out detail or to do NPR stuff.

OR and that would be the most important use case: Use it to accumulate dirt in the corners...hence the name VRayDirt