Ambient Occlusion pass.

[Rob49152]

I do most of my renders with the PMC render target but I need to do an AO only render pass. I'm not sure how to do that with octane. Not sure if this is even possible? I'd imagine the surface override would be used.

If there is a way to do this then there is a feature I'd love to have at some point in the future. When I name a surface I prefix the names so they group in the surface editor and are even easier to find quickly. Any name that begins with a '+ ' means that the surface emits light and "_" means that it is a specular surface allowing light through.

I'd love a feature that allows you to wildcard an over-ride. So I could say anything with a + means not to render AO but make it solid matte white. That way when I'm in my composite software I can do a multiply or color burn without getting shadows on something that's an emitter. It's painful to have to go in and paint in areas after the render.

Also that anything beginning with a _ would also not render AO pass but would also be 100% transparent So If I have a glass wall I can still see the AO on the objects on the other side.

Or maybe another way is a check box on the specular and emitter nodes that allows the user to 'override surface for AO'. And it would then do the different time of surface pass.

Anyways maybe this idea is just me. But I think it would be very handy option.

[juanjgon]

Currently you can exclude full objects from material override with the custom object plugin, but not each surface inside the objects. Anyway I have in my roadmap some improvements in the override system for the future releases.

-Juanjo

[Rob49152]

Just wondering if this is still on the roadmap? I have to spend hours doing post work to fix ambient occlusion images. And it's really slowing down deadlines.

Here's an example of the problem. This is a sample scene render;

As you can see there are light emitting areas that are recessed. The ceiling lights, the back of the shelves and the 'window' like area

[Rob49152]

This is what I get with the AO set to 1meter

As you can see the AO for the recessed areas is rather dark. When compositing these into the final image I'll use either 'multiply' or ' color burn' if I want a more dramatic effect. In some cases I'll use both.

[Rob49152]

So I usually have to spend a long time masking out, erasing or changing the brightness of the areas in question so they don't cause problems.

This is the default layer set to 'multiply' in PS. You can see it completely covers the light areas. But is ignored by the glass which I can't seem to get consistent transparency with AO. Sometimes it's solid and other times it's transparent.

[Rob49152]

So this is what I need to end up with to get the proper results for an AO pass.

This allows to use 'multiply' and 'color dodge' with very little problems. You can see this works really well for the pin-hole lights in the floor. I still have to spend some time with lights light the top one that hangs down (not recessed). The dark AO trim where the light surface meets the ceiling doesn't work.

It would be awesome that on a per-surface option to select it to render either solid white or a percentage getting close to white. 0% would be normal AO and the default. 50% would be light AO and 100% would be solid white. I don't know if that's possible with the way the system is? But it would save me hours if not days of clean up time.

Also I am not sure why sometimes the glass lets AO through and other times it doesn't??

[Rob49152]

This is the cleaned up AO pass set to 'multiply' and the default of 100% opacity.

This leaves the lit areas looking bright. And the pin-hole floor lights look good.

There is a strange effect of the AO behind the glass pane that's partially in front of the shelves. It leaves an AO shadow on the wall, but not on the wall that's visible directly through the glass. Also the AO on the glass spheres to the right really darkens them up. Look at the light reflection on the bottom sphere.

Also the gold spheres inside the glass tube to the right have no AO on them. So this requires another AO pass where I set the transparency of the glass surface to 100%.

[Rob49152]

So this is the final AO pass with the glass surface set to 100% transparent.

This is kind of a weird image in that it shows that AO doesn't respect surface transparency at all. But it is needed to fix the problems with the areas behind glass where there is no AO when the glass is 0% transparent.

[Micha]

+1

[Builtdown]

Hi,

When you render your AO image, put a low emission node value for the areas you don´t want AO to show?