here are some bits from the psg art tutorial by Arne Niklas Jansson
it’s incredibly useful and very comprehensive so please, check it out!
img 1: sub-surface scattering
Sub-surface scattering - Strong light can penetrate the surface of some materials and bounce around, then exit again. This will increase the saturation and make the surface look illuminated from the inside. In the case with human skin, we sometimes see it on hard edges between light and shadow.
img 2: layer passes
- Feel volume and angle of the form.
- Where is the light coming from?
- Try to figure out if there are any shadows that might be falling on the surface.
- Is there any reflected light (radiosity) that hits the surface?
- What is the ambient color of the scene? (sorta like global reflected light.)
- Any speculars. Is the surface gloss/wet and also angled so it reflects a light source, such as the sky?
- The exposure level. Perhaps it’s so heavily lit that it becomes more than white? Perhaps it’s so dark that even the brightest spot is hidden in darkness.
- Is there any fog in the way?
- The texture of the surface.
Note that this mainly goes for realistic styles. A brushstroke should also look efficient and consistent with the rest of the painting and your color scheme choice. You might also have an idea or style which disallows certain colors or textures and puts priority on other things. However, even in a powerpuff girls illustration there’s simplified elements of realistic rendering. Don’t hide behind “it’s not apart of my style so I’m not gonna learn it”.
img 3: speculars
There’s really just one kind of light. It bounces. You can only see the light (photon) if it enters your eye. Light does two important things when it hits a surface. First, a part of it is absorbed. This is how colors are made. A red apple reflects mostly red wavelengths, the rest are absorbed and turned into heat or something. That’s why black stuff get so hot in the sun. Anyways, the reflected light bounce away differently depending on the surface. If the surface is bumpy it will bounce away sort of randomly, like a tennis ball that hits rocky terrain. If the surface is smooth it will bounce away in a predictable path. A mirror is very smooth so the light comes back undistorted, so we can see our reflection.
Note that all surfaces have speculars, because speculars is just reflected light. It’s just more broken up/diluted on dull surfaces.
img 4: radiosity
Here on earth we have lots of stuff around us that the light can bounce off, so things here are more or less lit from all angles. For example we have the sky which is like a dome shaped blue light source. Then theres the ground, walls and other surfaces. In space there’s basically just one light source, the sun. This is why the moon just has a lit and shadowed side, and looks kind of flat. If you looks carefully however, you can see earthlight on the shadow side of the moon, but it’s very weak. Then there’s starlight, which I guess is even weaker.
When light hits a surface and bounces, it also change color. If it hits another surface of the same color it bounced off, it will make that surface look even more saturated.