real world unit of light intensity

[Anonymous]

Hi there,

I have a question regarding a unit of light intensity in Arnold. I am using Maya, which is not relevant to my question, though, I guess.

Lights in Arnold have attributes of intensity and exposure to control strength(or luminous intensity which sounds redundant) of lights. Is light intensity in real world unit such as candela, lumen? Or at least proportional to real world unit with a converting equation?

I wonder if I can have reference values of light intensities in Arnold to compare lights in real world and other renderers.

Thanks

[Stephen.Blair · Accepted solution]

Arnold units (including lightintensity) are arbitrary units, so there's no correspondence with other units of measure.

[Anonymous]

Hi Steve,

Thank you for the clear and quick answer.

I get to have a further question. Does "arbitrary unit" means that Arnold does not guarantee linearity of the values? Let say I set a light in a scene rendered almost like a 1000 lumens flashlight, then can I double the light intensity or raise exposure by 1 of a light to get 2000 lumens flashlight in a same scene?

I would like have some technical backgrounds to plan rendering tests with various lights in Arnold. It would be great to have references and resources about Arnold to read and learn other than docs.arnoldrenderer.com.

Thanks again!

[Stephen.Blair]

exposure=1 will give you double the amount of light.