[sebbo]

I have a question about which photometric units are used in the dome light and the physical sky ?

we want to have our hdr images physically correct in terms of real world light intensities and now we stuck a little
on which units to calibrate to as we don't really know what is used in maxwell.

also are the the units used in the dome the same as in area lights ?


cheers seb

[tom]

Intensity for skydome is cd/m2 (also called nit). Emitters have different options... Which plugin are you using?

[sebbo]

Maya is the plug in... but what about the dome light when using HDR images ?

[eric nixon]

I calibrate hdr's by setting the approx EV for the camera, then adjusting the gamma/exposure of the hdr. Beware that exr's can go out of range if pushed far enough (the sun spot will become black in the rendered reflections even though it remains white in photoshop) adjusting maxwells hdr sky intensity setting can overcome that problem.

[sebbo]

Hey Eric

my goal is to calibrate our HDRIs to real world values... so what im interessted is it the units used in maxwell so that we can adjust the pixel intensitys to it.
We used photomatics defaults but the is a discrapency with the factor of around 1000... so we are trying to understand the whole light unit thing a bit but get somehow confused with too many variables.

[eric nixon]

Well the only unit I would trust is the camera EV, but thats a good starting point. Maxwell sky seems to be out by a factor of seven in a recent test I did!

[AlexP]

Try sky intensity 0.2 and sun 5. Maxwell sky seems to be out of proportions too.