Intensity units for light materials

[Jpjapers]

It would be great to have the same intensity units available as part of the light material settings. The unitless approach now makes it difficult to match real units if youre using it.

[PROH]

I requested that a long time ago, and got the answer from Ondra, that this couldn't be done, because the light intensity is calculated based on the objects surface area - and this wouldn't be the same for all objects using the material (written out of my head, so it might not be totally accurate).

As far as I understood, the unit used now (watt), was the only one that could be used without before mentioned problem.

[Jpjapers]

I requested that a long time ago, and got the answer from Ondra, that this couldn't be done, because the light intensity is calculated based on the objects surface area - and this wouldn't be the same for all objects using the material (written out of my head, so it might not be totally accurate).

As far as I understood, the unit used now (watt), was the only one that could be used without before mentioned problem.

Oh i didnt realise it was measured in watts in the material. That should maybe be written next to the intensity box. I assumed it was unitless.

[maru]

The default unit, which is used for the Corona Light and for the Light Material is Watts per meter squared per steradian reflected into camera. :)
If you create a Corona Light and an object with exactly the same shape, and use the same intensity, you will get the same illumination from both.

The way you can "use" it is:
1) set up scene in correct units and scale
2) set up light sources with correct size, units, and intesity
3) optionally, for best fidelity, use PT+PT and set MSI to really high value (more than 100, higher = closer to reality)
4) disable any tone mapping, (even set gamma to 1.0!)
5) render
6) read data from VFB. Interpret the numbers as "Watts per meter squared per steradian reflected into camera" - "original RGB" 1,1,1 should mean 1 W/(sr.m^2)

(credit goes to Ondra, as usual ;) )

[Jpjapers]

The default unit, which is used for the Corona Light and for the Light Material is Watts per meter squared per steradian reflected into camera. :)
If you create a Corona Light and an object with exactly the same shape, and use the same intensity, you will get the same illumination from both.

The way you can "use" it is:
1) set up scene in correct units and scale
2) set up light sources with correct size, units, and intesity
3) optionally, for best fidelity, use PT+PT and set MSI to really high value (more than 100, higher = closer to reality)
4) disable any tone mapping, (even set gamma to 1.0!)
5) render
6) read data from VFB. Interpret the numbers as "Watts per meter squared per steradian reflected into camera" - "original RGB" 1,1,1 should mean 1 W/(sr.m^2)

(credit goes to Ondra, as usual ;) )

Ok cool thanks! Mini feature request to write (W/m2) next to the intensity spinner :)