Physical Camera Exposure and Image Plane

V-Ray for Maya V-Ray for Maya :: Issues
1

If you are using Physical Camera to match a plate using an Image plane you can’t get out of not having the camera exposure effect the image plane. The only way I got around this was by creating a plane and assigning a camera projection to the V-Ray Light material and turning on compensate camera exposure at shader.

Can compensate camera exposure be added to Image Plane, or is there another method to not have the exposure effect the background image?

THanks.

2

Instead of using an imagePlane or a geo plane, you can plug the projection node that you created directly into the background color slot in the environment tab of your camera attributes. Then if you turn off “affect background” in your render settings you should get what you want.

David

3

Thanks Scott and David for the tips. I was bothered by this before, but now I learned two workarounds.

Jason

4

Awesome David! Thanks.. That beats throwing up a plane with light material. Too bad DOF from physical camera isn’t ignored as well. :slight_smile:

5

Hi, David,

Have you tried this with RT? I tried the technique you mentioned and it worked for regular render. For example I change the aperture size of the Physical camera, the background plate is not affected between two renders. But if I use RT, as soon as I change the aperture size, the background turns into black!?

ps. am using ver. 2.004

6

V-Ray RT does not support the “Affect background” option; for the moment it always applies the color mapping as a post-process on the final pixels when the information required to separate the background is already lost.

It is on the “to do” list to add a “compensate exposure” option for image planes though.

Best regards,
Vlado

7

Thanks for the explanation, Vlado. Looking forward to the “compensate exposure” option for image planes.

8

Hey Vlado and devs,
Along the tangent of the issue mentioned in this thread, is this feature incorporated already or it’s replaced by other options somewhere else in the UI?
I did a quick check in one of the newer nightly of 3.4 and didn’t find any option like “compensate exposure” under physical camera or imagePlaneShpe node.

9

We are sorry to report but this feature is not developed yet.
We’ll keep you posted for any updates.

10

I cant replicate this bug…Using backplate / imagePlanes and RT-ing cars is my general workflow all day, and the first thing I do when I drop a dome light in is adjust the camera exposure so my values look realistic…and this doesnt affect my imagePlane. It used to, Im sure, and I found it very annoying, but at some point (I dont remember when) it stopped happening. So as far as I can see, I cant control the imagePlane exposure with the physical camera.

11

It’s still on the to-do list.

12

Hi,
rescuing up this thread to ask if there is any way of having a back plate not being affected by the tonemapping?
If i plug a camera projection with the plate image to the background override on render settings i get a clear match between what i get on render buffer and the original image plate… but with two big limitations.
We cant use the progressive mode neither use an exposure layer or any other layer on the frame buffer.
I understand that a post processing layer (as a color corrector or a glow pass) should affect the entire render area but i think that we should be able to adjust exposure on the rendered assets without compromising the background plate if we wish so.
Is there any workaround that im not aware of?

thanks

13

Have you considered using masks?

14

i am also wondering if there is any way to disable dof for image planes?
this would be very useful for quick preview renders with the physical camera.
VFB background is not affected but very limited with its placement, enviroment background is also problematic. we often use 2d pan zoom and there is no easy way to replicate that. unless i miss how we could apply the image plane into the enviroment background in some way (maya 2024 vray 7)
right now i am considering a mini post job after render which would be avoidable if we could disable dof on certain or all image planes

15

Just tested Image Plane + Dof in Arnold, and there it seems to have the opposite problem - it’s always disabled (or at least I couldn’t find a way to turn it on). Anyway, it seems like a good idea to have an option for this. Add it to the Ideas Portal.

16

yeh I had to test this to believe it…seems wild to me that image planes would get blurred by DOF. Obviously my workflow never needs them in render, or Id have known this by now, but still seems like they shouldnt be affected for sure.

17

added this to the ideas portal. i read somewhere that it is not trivial to exclude image planes but i cant remember where and if arnold manages this then it should be possible.