Get floor with AO map as a separate render element

[kimmo_hernborg]

I have a scene where I need to use an AO map as ground shadows. I will be doing some light compositing in photoshop and my images need to have a transparent background, so I would need to have a separate element with just the AO map from the ground plane since a want to be able to manually adjust how strong it is in PS, and not have it be effected by any elements I might add.

I have added an AO map in extra tex element, and have it include only the ground plane. I’ve also added a VrayObjectProperties-tag and played around with the settings, but haven’t been able to achive the desired result.

Any suggestions? I need the usual render elements (lighting, GI, reflection etc) but without the ground AO map visible in those, and I need an extra render element with just the ground AO map.

[viktor_angelov]

Hello kimmo_hernborg

What you need to do is follow 4 simple steps:
1. Create an Extra Tex Render Element
2. Add a V-Ray Dirt texture to the Texture slot
3. Set the Mode to Included
4. Drag the desired geometry to the Object window

I have created a visual representation of the steps for you as well. Please, find it useful: http://ftp.chaosgroup.com/support/sc...8_10-18-40.jpg

[viktor_angelov]

Hello kimmo_hernborg

What you need to do is follow 4 simple steps:
1. Create an Extra Tex Render Element
2. Add a V-Ray Dirt texture to the Texture slot
3. Set the Mode to Included
4. Drag the desired geometry to the Object window

I have created a visual representation of the steps for you as well. Please, find it useful: http://ftp.chaosgroup.com/support/sc...8_10-18-40.jpg

[kimmo_hernborg]

Hi Viktor

Thanks for your help. I still haven´t been able to get the result I want though.

The best would be if the AO map only showed up in the extra tex render element, and not in the main render or any of the other render elements.

I´ve tried to achieve this by making the plane a shadow catcher object, but I have turned off the shadows checkbox in the vray properties tag (I dont want any normal shadows on the ground, only AO).

When I check the element in the VRB after renderings it looks fine. But on the saved extra tex render element render there are black pixels where objects which are not the plane are, and transparent pixels where the plane is.

I´ve also tried exluding the plane from the normal rendering by removing the shadow catcher tag and instead applying a material which is transparent (a vray material with a black opacity chanel), hoping that this will make the plane invisible in the normal rendering but still yield the ao map on the plane in the extra tex chanel.

I get the same results as with the shadow catcher method: the AO map is shown when viewing the extra tex element in the VRB but the plane is transparent in the saved extra tex file.

[viktor_angelov]

Hello kimmo_hernborg

I understand you need a AO map of the Ground only in a separate Render Element. Is that correct?

If yes, then the proposed set-up should do the job. I am attaching a new video. Please, notice how the AO Map is in a separate Render Element and does not affect any of the other channels: http://ftp.chaosgroup.com/support/sc...4_11-38-41.mp4

If this is not what you aim for, please send us a visual representation of what your current outcome is as well as what you would change.

[kimmo_hernborg]

Hi Viktor

Thanks again for your help. I think I might have been unclear.


It seems to be what I need, except I want the ground plane to be invisable in all passes except the ExtraTex/AO pass. In your example I would need every pass (except extra tex) to just be the cube without the ground plane.

[viktor_angelov]

Hello kimmo_hernborg

What you can do is create a Mask and remove the Ground Plane in post. Render the Background separately and then combine the Background and Foreground together. Finally, apply the AO pass.

Let me know if this would work for you.

[kimmo_hernborg]

Hi Viktor

Thanks, I´ve thought about that solution. Idealy I would want to get everything I need in one render. Over time doing double renderings would lead to alot of extra work.