Spec Intensity goes wild

[Anonymous]

Hi i'm facing an issue wich happens in Arnold 4 (alSurface) and 5 (aiStandardsurface)

If i'm creating a shader with metal intensity 1 and a plain directional light with intensity of 1 it results in specular values of upto 500! This value decreases by increasing the radius/angle of the light - in my simple example i had to use an angle of 60 to get the spec values to something around 1.

If i use a skydomelight the specular intensity values matches the intensity of the light. Wich is what i would expect.

Why is that?

What can i do to tame the the spec intensity ? Clamping would be my last option.

thanks for any input

[gshankar165]

Yah. If feel same. Render setting clamping option would be better.

[zenop]

This is because it's relative to the solid angle of the light. A skydome will distribute the values over the whole hemisphere whilst a directional light will contain it within it's angular value.

If you'd capture the value of the sun on a reflective sphere, you'd see exactly the same behaviour.

To work around this you can do multiple things:

- Create a rougher material, pretty much everything in real life has imperfections
- Create a less reflective material, most materials are not nearly as reflective as you'd think in real life - even metals.
- Increase the solidangle of the light

You should avoid clamping at all costs in this situation.