Adjusting VFB Curve breaks compositing workflow

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

I’m trying to recreate my beauty pass from renders saved out with a VFB curve baked inside photoshop but it only works with the curve off.
is this a bug? I tried saving out individually from the VFB instead of the multi save option and still no go!
Cheers for any help, this is a really urgent problem for me :frowning:

2

Damn, so I’ve just realised the curves adjustment in the VFB isn’t floating point. omg :frowning:

3

It is fully floating-point when writing the final images. But not when adjusting interactively (it’s lower precision for speed reasons for display).

Other than that, it is normal that you won’t be able to composite things properly if they have any sort of color correction except. If you plan on compositing anything after the render, you need to render linear colors and do any color correction after all the compositing is done.

Best regards,
Vlado

4

How come when I save a 32bit exr with a VFB curves adjustment, I lose all my floating point values in photoshop CC?
It’s limited to 255 colors, are you 100% sure?
On the left is saved out with the curves, right is linear

772×648 73.7 KB

5

Dude, you really need to read my posts, you’re always 2 weeks behind :stuck_out_tongue:

I don’t think it saves full float.
I showed the issue here but I think it has been lost in the sea of comments of that post :

http://forums.chaosgroup.com/showthread.php?83887-Request-Film-Response-Curves-(Comparing-Octane-to-V-Ray)&p=661836#post661836

Stan

6

I saw that post but have been so busy producing the lesson I didn’t take notice! Jesus!
Ok well I’m going to get the lesson out and pinpoint it as a bug/problem and hope it’s fixed for the next one!

Cheers

7

Just bumping this thread, is there any hope of having this looked at? I was really hoping to incorporate the curve adjustment into my workflow but had to make some last minute changes to the lesson which might confuse some people.
Cheers!

8

I’m totally sure that it does save as floats - just tried it now. Whether it saves as HDR though depends on the last point of the curve - you need to make sure it doesn’t truncate to white. From what I can see, adding points to the curve resets the right tangent of the last point, which is more likely the problem.

Best regards,
Vlado

9

Here are some screengrabs to make this clearer - after you add a point to the middle of the curve, the last point is reset to truncate values about white. You will need to adjust the tangents of the point depending on what you want to happen to your highlights.

(we should probably adjust those colors though, it’s really hard to see the curve).

Best regards,
Vlado

curve_orig.png
curve_orig.png1020×580 32.6 KB

curve_added.png
curve_added.png1020×580 33.2 KB

curve_adjusted.png
curve_adjusted.png1020×580 33.4 KB

10

Yep correct, if I make sure the info above 1 so not clamped, it works.
I’ll keep a mental note to make sure to double check that.
Cheers
Stan

11

Grant, are you aware that you can save the Vray VFB curve as a Photoshop curve? So you composite your passes in Photoshop or AE in linear space and load the Vray curve preset in a Curve adjustment layer on top of everything.

Regards,
-Eugenio

12

I was about to post the same thing. Just right click on the curve and save out the preset and load it back in later.

13

I actually explain that in the lesson but the curves simply don’t match…

14

Thank you so much! Would have been great to include that in the lesson :frowning:

15

May I ask how you ad a point to the curve? I can’t seem to figure out how. Cheers

16

I believe it’s ctrl+left click on the curve.

17

The V-Ray docs list the available controls:

Best regards,
Vlado