A common question I get from other 3D artists:
"Why do you have those spheres? What do they tell you?"
The two spheres in my LookDev environments serve as a way to monitor the impact of lighting on my work. The bottom sphere is shadeless, meaning that the lighting in the scene has no impact on it, and it has a specific value that remains constant. The top sphere is identical in value, but it is influenced by the scene's lighting. By comparing the two, I can see how much my scene alters in color and value. Take this scene for instance. See how the top sphere is roughly the same value and color as the bottom shadeless sphere? This tells me it's relatively "accurate." Of course, accurate here is a tricky word, but I'll get more into that soon:
Compare that to this next scene, where the lighting influence is much more blue. Of course, you might not notice just how much more blue without our bottom, control sphere. This is a perfectly valid LookDev scene as well. The bottom sphere simply gives our brain more context into value and color. Without it, there's a chance we might paint everything a bit too orange during texturing, to compensate for the blue scene. I'll get into brains and color adaptivity in a moment. It's something called "color constancy." More on that momentarily:
But why is this necessary? Well, it all comes down to the fact that color is relative. Our eyes and brains constantly adjust to the light around us, making it challenging to accurately perceive colors. To understand why, we need to take a closer look at how our eyes work.
Our eyes contain two types of cells that are responsible for our perception of color: rods and cones. Rods are responsible for seeing in low light conditions, while cones help us see color. There are three types of cones, each sensitive to a different wavelength of light: red, green, and blue.
When we look at a colored object, the cones in our eyes respond to the wavelengths of light reflected off that object, and our brain processes this information to create a perception of color. But here's where things get interesting: the cones in our eyes don't just respond to the wavelengths of light in the object we're looking at. They also respond to the wavelengths of light in the surrounding environment.
This means that if we look at an object with a particular color for too long, our eyes and brain adjust to the surrounding light, making the color appear less intense. This is known as "color adaptation" or "color constancy." Essentially, our brains adjust our perception of color to account for changes in lighting so that we can still perceive colors accurately, even in varying lighting conditions.
So, what does all of this have to do with my spheres? Well, as I mentioned earlier, the shadeless bottom sphere provides a specific value that remains constant, while the top sphere is influenced by the scene's lighting. By comparing the two, I can see how much my scene alters in color and value. This helps me ensure that the colors I'm using in my work are accurate and consistent, even when viewed in different lighting conditions.
"And what about the mirror sphere? And what's up with that color chart thingy?"
You may have also scene a setup in vfx that looks something like this. It's a mirror ball, another rough sphere, and a color chart.
This LookDev environment (created by artist Thiago Sul. Yes, this is a rendering😲) accomplishes more or less the same thing, but with some added benefits. We still have the specific gray sphere on the left being influenced by lighting in the scene. On the right, we have a chrome sphere meant to reflect the entire scene to give the viewer further context into the lighting. On the bottom, we have an xrite color calibration chart. These charts are available for purchase in "the real world." They're essentially a collection of very consistent, very accurate colors. When brought into a digital environment, just like with our shadeless ball, we know what the baseline, non shaded colors should look like. Because of this, we're able to essentially negate effects from the environments lighting, and bring the image back to a controlled, predictable baseline.