Hi, friends
Today I decided to figure out the the reasons of a little bit strange (in my opinion) lighting calculation in Cycles.
We all know, that Cycles is physically based unbiased render. So as I understand it calculates light transfer according to some physical laws, which in the end gives us more realistic results.
I also hope that Cycles calculates all lighting linearly, according to linear color space workflow.
So during a long time working with Cycles I noticed, that I always have to overbrighten the lightsources to lit the scene with appropriate amount of light.
Look at this image
https://docs.google.com/file/d/0ByHRy_pSYAhgd1hQZy1Pcl9tX2M/edit?usp=docslist_api
Notice how overblown the lightsources is. I had to gain the lightsources strength 3x times to lit the cloth on the background. Notice, how unrealistic (in my opinion) tell image looks. The lightsources is overbrighten, and there were also have this overbrighten light spot on the floor under the lightsources.
Now look at this image
https://docs.google.com/file/d/0ByHRy_pSYAhgSGdFeWJCb2Z2ejg/edit?usp=docslist_api
This image and the previous one looks identical exapt the lightsources. It is not overbrighten now. In this image I left the strength of the lightsources at one, but I multipled all the colors in the materials by 3. In this case everything looks realistic exapt the overbrighten light spots under the lightsources.
Now, look at the third image
https://docs.google.com/file/d/0ByHRy_pSYAhgZE1lVTBjNEpJR2s/edit?usp=docslist_api
Notice, how realistic (in my opinion) it looks in terms of light behavior. Here I did the same operations with the colors, but I also added the Light Falloff operation to the lightsources with the smooth 0.2.
And looking at this 3 images, I’m asking myself, why it is so? Why I have to overbrighten the lightsources, or gain the materials colors extremely to get the appropriate lighting in the scene.
It is very important to me, because in this situation I have to use much more lightsources to lit the scene, I also receive much more contrast results in this case, and it is much harder to get realistic results without these tricks. All these symptoms saying to me, that the deal is in the linear workflow in Cycles, and looks like something is not working properly in it. Or maybe I don’t understand something.
P.S. There is no indirect light in the scene. Only direct.