Author Topic: Render selected object inside a volume  (Read 643 times)

2023-03-17, 13:28:55

second ich

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Hello,

I need to render a selected object, but it is inside a "fog volume" (box with CoronaVolumeMTL). So it always considers the fog volume in front of the selected object and renders a black image. Is there a way around this?

Thank you

2023-03-17, 13:50:55
Reply #1

TomG

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Not sure entirely what you need, solutions would seem to be

- Include the fog object as part of the selection being rendered
- Manually disable the fog object from being rendered just for this object selection render

Those don't fit the need/process?
Tom Grimes | chaos-corona.com
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2023-03-17, 14:57:19
Reply #2

second ich

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I need to render 1 object of an animation. The fog covers the entire screen and the object is inside the fog.

So if I select the fog as well then everything will be rendered and if I disable the fog then the object will look different since it is affected by the fog.

2023-03-17, 15:48:40
Reply #3

maru

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What you need to render is the object affected by the fog or not? Should it appear covered by the fog or not?
If not, then should it be affected by shadows of other objects? Should it be affected by lights?
Marcin Miodek | chaos-corona.com
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2023-03-17, 16:11:33
Reply #4

davemahi

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I think what they are saying is that you can't “render selected” an object in a volume. The Volume renders everything that is inside, even if render selected is used.

2023-03-17, 16:15:17
Reply #5

second ich

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Yes, probably have to use region render and move it if the object moves in the animation.
« Last Edit: 2023-03-17, 16:24:02 by second ich »

2023-03-17, 16:31:04
Reply #6

TomG

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From what is described, does sound like render selected (on its own at least) is not the solution. Depends on the purpose, to save render time, or to allow editing the object independently in post? If the second, then using some object mask render element should let the object be isolated in post, with no need to change the render.

If it's about render time, not sure - region render as noted could work, depends on whether the object will be moving around its location within the frame as not sure render regions can be animated. If not, then another possible workaround is using a plane with 0 roughness, 1.0 IOR, full refraction, and use that as the sole render selected object. Since "what it sees in refraction" is fully maintained as part of its render selected, this plane then becomes a "window" through which only that part of the scene is rendered. Most likely this would need to be right up close to the camera (else the depth of the fog may be different). Not the easiest of set ups, but you can then at least animate that plane to follow the camera, and even to move around in the frame to always keep the desired selected object in view.

EDIT - crude test scene attached in case the description of that last set up was somewhat confusing in text form :)
Tom Grimes | chaos-corona.com
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2023-03-17, 20:35:57
Reply #7

second ich

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Yes, it's about render time.

If not, then another possible workaround is using a plane with 0 roughness, 1.0 IOR, full refraction, and use that as the sole render selected object.

I actually tried this before, but since I'm using DOF and the plane needs to be very close to the camera because of the fog volume, it's completely blurred.

Would be a nice feature to add a select render option for objects in a volume or behind transparent objects.

2023-03-17, 21:13:12
Reply #8

davemahi

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I actually tried this before, but since I'm using DOF and the plane needs to be very close to the camera because of the fog volume, it's completely blurred.

Would be a nice feature to add a select render option for objects in a volume or behind transparent objects.
[/quote]

Yes I have run into this issue many times and wished there was an option.