Clamping Output Values

[Intenzity]

I found a couple references but not exactly the answer.

Vray clips the bright values at 1. The problem arose from a previous project that the client does all the post work using .exr files. They ideally want .exr files with bright values reaching the range from 3-4.

So my question is how can I achieve reaching those bright values without vray clamping them.

(Using Vray 1.5sp2 - I have clamp output unchecked.)

Thanks in advance.

- A

[duke2]

Output EXR's, with clamping off, and the renders won't be clamped unless you're using Exponential color mapping or something.

[Intenzity]

Clamping is off but it's still constraining the value to 1. I know by default Linear multiply clamps the value as does Reinhard. I haven't tried the others since I was assuming that the other color mapping methods clamp the bright values to 1 by default.

[rmejia]

Linear does not clamp the value. Exponential clamps the value. Reinhard is a mix of linear and exponential, in 0 burn it is exponential, in 1 burn value it is linear, so any value other than 0 will not clamp the colors to 1.0

[Intenzity]

I must be doing something wrong then. I had read on the manual that values above 1.0 will be clipped. I had understood that to be clamped. But your screenshot proves otherwise.

Just out of curiousity are you using vray sp3a and would it make a difference?

Thanks.

- A

[rmejia]

I am using SP3a, but that should not make a difference. As far as I know the only reason that they would be clamped in the frame buffer is if "Clamp output" is checked. When you render and inspect the pixel information, there is no value greater than 1.0 ?

Values over 1.0 are clipped (different from clamped), because monitors can't display any value above 1.0, but the color information is still there. So the exposure can be adjusted later using a file format like .exr that stores in full float.

[sv]

the problem could be in the post application, rather than vray. i.e. the post application is clamping the hdr data somewhere.
Vray does not clamp the data, unless you specify that option in the colour mapping...
SP2 / SP3 etc won't make any difference...