I have been giving a lot of thought to what makes a 3d model realistic enough so you would be hard pressed to see its not a photo. Watching and reading about photography techniques for lighting and props i began experiments in photorealistic renders only to have my hopes dashed over and over again. I thought to myself if used proper real world lighting techniques I.E. Shutter speeds , iso values and Fstop and using shaders that used true PBR material values i could get close. Much to my chagrin that didnt help, and in a lot of my experiments seemed to go backwards.
I began questioning to myself about what makes a render look photo real. Is it the light and shadow? That is part of the equation to be sure but understanding how iray lighting works and the ability to create mesh, and photometric lights that behave like real studio lights with proper temp ranges and lumen values you still cant get there. So its not the lights. I then thought maybe its the models themselves. Perhaps they look too doll like to be shot to be photo real. I noticed something in some of the models i use if you cut off the heads during the render the skin textures are very life like, details like stretch marks and skin imperfections looked very real and even more so in a well propped room. I said to myself what if it is the models faces themselves because this seemed to indicate that there must be something wrong with the head and face. So i began experimenting with up close face portraits. After a few dozen attempts i managed to get some portraits that almost hit that uncanny valley. So now i am scratching my head.
If it wasn't the head and face what clues did i have for what was wrong. I kept using real photo's for reference because i was determined to find the answer. At first i thought it had been the lack of details in a 3d models skin. But looking at a lot of artistic nudes i noticed that alot of them had skin that was so smooth genetically, or completely airbrushed to remove all fine details and blemish that Vicky 4 would be put to shame for how smooth and even their skin tone is. And yet looking at those photos i knew right away it was a photo. So skin details isnt the problem. So on it went, first the hair, then the topology then the makeup, shaders, light tricks, reflections, subsurface scattering, you name it i tried it and i am not closer to my goal of hitting that uncanny valley. Some of my renders come so close but one look it is apparent that it is a render. Even artists that are far more skilled at lighting, shaders and postwork get so close and yet 1 pass over a render and you know its a render and not a photo. I am still scratching my head but the experiments continue. I realize that alot of people feel that 3d art should be a fantasy representation of real photo's but i for 1 want more out of them. So i continue not even knowing where to start to remedy this.