compositing question: swapping out textures

[peterguthrie]

I have to render a gallery scene, and be able to swap out the paintings in post (for speed)

whats the best way to do this bearing in mind I'd like the lighting to be correct and the paintings might be behind glass (maybe too difficult?) so there might be reflections involved.

Its ultimately for a website, so I guess I need one transparent image that gets overlaid onto the new painting

thanks in advance for your collective knowledge!

[Donald2B]

This is pretty simple.

Just separate out all of your layers (Diffuse, Lighting, GI, Reflections, Refractions, Speculars, etc...)
Put them back together in your favorite compositing package (Nuke, Fusion, AFX, etc...)

Then once the layers are all put back together, make sure you have a matte for the white areas and then put the artwork in the diffuse channel and then all the other effects will then be placed on top of them correctly.

I am just giving a basic overview, I could try to find something that goes into more depth if you want to?

[peterguthrie]

thanks, thats what I have been doing but was hoping there might be an easier way, and one that will work in photoshop. Ideally I'd like just the hand over a psd and be done with it, plus the web guy needs a simple transparent image he can put on top of the new image. There could be hundreds of new paintings, so to have to open up AE every time wouldnt be realistic.

[simmsimaging]

You can render the frame once with a solid black "painting" in it and then take the glass area of that image, or the reflection pass from that image, and layer that on top of your new content painting images in Photoshop. Set it to linear dodge mode to drop out the black and you should be good to go to swap out the underlying images at will. Might need to do some levels/curves work on the reflection layer but this approach works great. Another layer or three for some shadowing of the frame onto the image should finish it off nicely.

[Donald2B]

Yeah, that gets to be a lot more difficult.

I'm not really sure what to suggest other than maybe "faking" it with some photoshop layers to simulate the lighting and reflections and then he could just replace the "artwork" layer and resave the image?

[pg1]

When I render an interior for an apartment I usually render it over black i.e. no background so I can replace the background with any sky. This is more or less the same for what you want to do.

make a hole where the painting would be, leaving the background black.
render the image with glass material set to affect all channels, glass should have reflections and you will be able to use the image alpha to put any image you want behind it.

You could then convert the painting layer to a smart object.Then you would just have to open the smart layer copy in the new image and save.
All the web guys would have to do is make sure all the paintings are same size.