How to composite 3ds Max / V-Ray CGI in After Effects

[vladimir_djukic]

Hello guys,

I need your help... I've struggled for weeks to figure out one thing, and that is what is the best way to export 3d scenes so I can have better control in my composition software - After Effects.


I am using V-Ray, and this is my example.




I shot green screen footage and keyed it in After Effects. Using bitmap and image to plane I managed to put my model into 3ds max environment.

1. How I can export only my model (girl in picture) separately using V-Ray, and background separately so I have more control in other software? I guess the solution is simple, but I can't just find it.
2. When I render exr sequence it's not rendering sky and clouds from hdri (it is transparent), what is solution for that?
3. Does anyone know the best way to do this kind of shots in 3Ds Max, is it the right choice to use image to plane, or?

I tied cryptomatte, and it works fine but not for exr sequence, it always crash After Effects... Is a better way to use State Sets? I tried that too, but I can't composite it right, because it renders the whole image (green screen model), not only visible parts.

Please if someone has good workflow for 3ds max / Vray and VFX, share it with me.

Thank you all...

[hermit.crab]

1. How I can export only my model (girl in picture) separately using V-Ray, and background separately so I have more control in other software? I guess the solution is simple, but I can't just find it.
2. When I render exr sequence it's not rendering sky and clouds from hdri (it is transparent), what is solution for that?
3. Does anyone know the best way to do this kind of shots in 3Ds Max, is it the right choice to use image to plane, or?

1. One way is masking - you've already tried Cryptomattes, but check the other Matte Render Elements. For the background, it's easier to use the VRayBackground element.
2. This depends on the way you've set the HDRI and the scene's lighting. If you've set the HDRI as an Environment Background, make sure VRayDomes' invisible checkbox is ticked.
If the background is not visible in After Effects, it most likely is because the Alpha is premultiplied. Check the footage properties.
3. Somebody with more practical experience can answer this better, however, I doubt that there's much variety in the methods.

[vladimir_djukic]

Hello Aleksandar,

When I saw your link to Matte Render Elements I managed to set Object ID with VRayMultiMatte and put out a red, blue, and green channel, after that, I simply used "Shift channels" effect in After Effects, then set a, etc. red channel to alpha, and made a perfect mask around my subject. Thanks a lot for help.

[Joelaff]

In answer to Number 3, I would first see if there was a way to keep the talent (woman) in comp software the whole time, using the camera from 3d, but I am not sure how well AE can do this (I think pretty well these days-- we don't use AE). Sometimes you can't do this for technical reasons, but it will usually produce a higher quality result.

But let's say you want to keep her in 3d in Max. Then it would depend on how much the camera moves. First try is a card (plane) in 3d space. If this looks good, and doesn't look flat due to the lack of parallax with the camera motion then you are done. Next would be to bend or sculpt the card to give it a little depth around her outline so that you could get some parallax if the camera moves. Another approach is to apply a displacement map to the card using a blurred alpha of the woman in order to round the edges a bit again to try to get some parallax. You can also use displacement to bring her head and nose out for a better effect. (All of this is moot if the camera does not move-- just use a card.) Finally, you could model full stand-in geo for the woman (like a 3d model of the woman) and project the image onto it. This is the hardest, and rarely needed.

For Number 1 you could use layers in Max and set up Scene States (or use a scene manager) where you can make the other elements not visible to the camera, or make them be matte objects, etc. You just have to figure what what are the combinations of setups that you need to get both the rendered data, and any mattes exported. If you make the woman separate than you will have to add the glow back in post (could render the effects result channel). Read the Chaos docs on Matte Objects and/or VRayMtlWrapper.