So in my testing I'm not seeing much difference in using surface brightness on emission surfaces other than the increase in brightness.
Meaning if I have an emitter that is set at a power of 20 with Surface Brightness checked and another emitter set at power of about 120 without surface brightness checked I get the same result.
I'm wondering if there is an advantage to using this..or what the thought was when included in the system? Thanks for any thoughts....
Surface Brightness or NOT That is the question...
Moderator: juanjgon
If you enable the option "surface brightness" in an emitter material, the power defines the radiosity, i.e. the amount of energy emitted per area. If you disable the option, the power defines the luminosity, i.e. amount of energy emitted over the whole area of the material.
In other words, if you scale up an object and thus increase the surface area of the object, the pixel colour of the emitter stays constant, if you enable "surface brightness" and gets darker if you disable the option. On the other hand, the amount of energy emitted by the emitter increases when you scale up the object and have "surface brightness" enabled, but stays constant if you have the option disabled.
So you turn on "surface brightness" if you are interested in the brightness of the emitter itself and turn it off if you are interested in the illumination of the surrounding of the emitter.
By the way, if you enable "surface brightness" and set the diffuse channel of the diffuse material to black, and use a texture emitter with a RGB spectrum texture and set its power to 1, and also set the camera imager to linear, switch off vignette, set exposure to 1 and gamma to 2.2, the colour of the emitter in the rendering on will almost exactly match the colour of the picked emission colour.
In other words, if you scale up an object and thus increase the surface area of the object, the pixel colour of the emitter stays constant, if you enable "surface brightness" and gets darker if you disable the option. On the other hand, the amount of energy emitted by the emitter increases when you scale up the object and have "surface brightness" enabled, but stays constant if you have the option disabled.
So you turn on "surface brightness" if you are interested in the brightness of the emitter itself and turn it off if you are interested in the illumination of the surrounding of the emitter.
By the way, if you enable "surface brightness" and set the diffuse channel of the diffuse material to black, and use a texture emitter with a RGB spectrum texture and set its power to 1, and also set the camera imager to linear, switch off vignette, set exposure to 1 and gamma to 2.2, the colour of the emitter in the rendering on will almost exactly match the colour of the picked emission colour.
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra