VrayRT does not work with Exposure Control of the Physical Cam

V-Ray V-Ray for 3ds Max Issues
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1

Hi,
I work a lot with the Vray Physical Cam, its Exposure Settings and Vray RT.
Unfortunately I have always the Problem that my render appears a lot darker in Vray RT if I use the Vray Physical Cam with Exposure.
It seems it cannot handle the Exposure Settings in the Vray Cam, or am I missing something?:face_with_spiral_eyes:
While rendering without Exposure or with the standard Max Cam it works very well.
Can somebody help me with that?
Thanks
Jon

VrayRT_Exposure_Problem.jpg
VrayRT_Exposure_Problem.jpg942×531 111 KB

2

This might be a gamma problem, what are your color mapping settings?

3

I render everything in linear space and tell the VFB to display the picture in sRGB space. I thought the Vray RT frame buffer does the same thing?
As mentioned if I render without the exposure control with the same color mapping it works.

Jon

color_mapping_exp_prob.JPG
color_mapping_exp_prob.JPG341×174 11.8 KB

4

Could you put your mode to ‘Color mapping and gamma’ instead of ‘Color mapping only (no gamma)’, and see if that helps.

5

Yea I can change it to color “mapping and gamma” to burn in the correction but the difference between VFB and VRTFB is still there while rendering with exposure controll in the camera.

6

Very quick test, but I can’t reproduce your problem. (I only have Vray 2.40.03 here at my job though, but don’t have this problem at home either)

Edit: make sure, your gamma in max is set to 2.2 as you can see in my screenshot, if it’s at 1.0 your active shade is affected.

Capture.JPG
Capture.JPG1143×437 64.7 KB

7

Thx for your Support. Its strange, I checked it with different workstations here in the Studio and all have that issue. I will switch later back to 2.4 and give it a try.
Jon

8

As mentioned above ( I edited my post, you might have missed it ) are your gamma settings for max at 2.2? I don’t have the problem with 3.00.05 at home.

9

Ah Yes I missed it. Its always on 2.2 yes.
I noticed that we currently rendering with 3.00.03 maybe that could be the reason!

10

I haven’t tried previous builds of vray 3.0 yet, but I doubt that the vray Version has anything to do with it. Although updating might not hurt.

11

Yes I still have the same Problem even with 3.00.05

12

Send me your test scene to have a look :slight_smile: peter.matanov@chaosgroup.com

13

It’s a known bug, turn off sub-pixel mapping. For more info:

http://forums.chaosgroup.com/showthread.php?78010-Dark-RT-CPU-RENDER

14

Ah, that’s why, I don’t use subpixel mapping :smile:

15

Thanks anybody for helping me to clear this up. With this Sub Pixel Workaround RT works like a charm again :slight_smile:

16

Sub-Pixels Mapping issue in V-Ray RT has been fixed for the next official service pack.

17

hey great ! Thank you for the information.
Jon