HDRI Dome Light Exposure VS Nuke grade

[jakob.schwarzAHQFZ]

Hi guys,

I stumbled upon a behaviour I didn't expect. I have a simple dome light with a hdri lighting my scene. I want to make it brighter so I cranked up the exposure to 1 (intensity stays at 1). So I doubled my light power from 1 to 2 (color * intensity * 2^exposure formula). So far so good.

For the lightrig setup I'm building, I need the exposure to be at 0, so I simply wanted to grade the hdri image in nuke to the desired value. I used a grade node and cranked up the multiply from 1 to 2. So now my values doubled.

When I now change my file node to my new brighter hdri and leave the exposure at 0 the direct camera rays from the dome light are correct, but the light hitting the objects in my scene is way to dark? I don't get it. It seems like the texture is clamped or something? But I can't find anything where that should happen... Any ideas? Is my math wrong? Tx files are not the issue. Any hints would be highly appreciated 🙂

J

[jakob.schwarzAHQFZ]

For those who might stumple upon the same issue. It was a simple 16bit clipping in the highest value. Rendering the hdri exr as 32bit fixed the issue.