Obtaining something like a "renderbox"

[Digitaline]

Hello everyone,

I am working on a sci-fi project, and we want to obtain a certain effect.
Having a character levitate some kind of hologram above a desk, hologram in the shape of a box, like a cubic screen.
And inside this cubic hologram display, zooming on certains parts of a 3D model.
while the cubic hologram screen remains at the same size on the desk.

The thing is, the concept seems like basic sci-fi stuff, but we have absolutely no idea how to obtain this effect in 3D.

We thought of Bolean meshes, but the bolean way of "cutting" objects is not dynamic.
Or to fake the effect using a DepthofField map, but it would only help us hide background objects, and not foreground.

The ideal would be to have a "render box", a box in the scene where everything inside is rendered, and everything outside is not.
The hard part is also to have the meshes "sliced" and not just hide then unhide.

Would by any chance any of you know a way or if it's plainly impossible?

We are currently using octane on Maya.

[Digitaline]

I got some succesfull attempts using the "cut face tool", and parenting their gyzmos to locators on the side of the "renderbox", but I still have issue with animated objects.

the "cut" act as if the animated object was still at the same spot as he was at frame 1
Despite the fact that he had moved.

[Bulwerk]

Try to make a specular material with a refractive index of 1 and no roughness. Apply that material to the cube volume you desire. Apply an Octane object tag to all the geometry that you want in the interior and toggle to "Camera visibility" At least this is what works inside C4D plugin.

[senorpablo]

There are a number of ways to do this in 3ds Max. Animated booleans, or a modifier stack including slice and cap.

[Digitaline]

Yeah, the maya's "cut face" tool is similar to the Max's "slice" modifier.

Try to make a specular material with a refractive index of 1 and no roughness. Apply that material to the cube volume you desire. Apply an Octane object tag to all the geometry that you want in the interior and toggle to "Camera visibility" At least this is what works inside C4D plugin.

This seems a lot simpler that what I have done. Thanks!
As far as I understand, the C4D "object tag" is the "Octane geometry type: Movable proxy" in Maya. And allow the object to be refreshed in real time in the IPR render view and to be hide from the camera.

But What do you mean by "Toggle to camera visibility?" ?
In maya, the camera visibilty can be 0 or 1, off and on. And I don't see what I can do make the objects "half hidden" using the specular refractive box.
The objects would go from visible to invisble in a snap.
What exactly did you do you?

[Digitaline]

Haha.

Just got it. This is geniusly simple.
Thanks!

[Bulwerk]

Glad it worked!

[Digitaline]

Too bad we still see "beyond" the cube. It shows the infinity behind itself, and not just its sinside.
But still, it will suits most effects.