Shading Technique

[whipstache]

I know I've been absent recently, but it's because I've been working, honest!

I just wanted to post a little shot of a rough WIP, because I've developed a new technique for doing building shadows. At least, that's what I'm using it for. I imagine it could be adapted for a number of different things.

And, it's not perfect, but, I think it works here.

It's probably something you all already know how to do. If, however, someone is interested in how I've gone about it, I'll write up a short tutorial guide.




As always, comments and critique are welcome and encouraged!

EDIT: If someone thinks this thread should go somewhere else, by all means...

[Falconius]

I think it looks pretty darn cool. However that is not how shadows (or rather light) behaves in reality. I think it does gives a strong indication of information about what is happening on the map, so it may be a good choice. Where as a more solid shadow may not give as much info.

[whipstache]

Thanks! I generally lean more towards an illustrated style over realism in my maps.

But, out of curiosity, what would make it more realistic? Less of a gradient effect and more single tone?

[Falconius]

Yeah pretty much.

A factor that modulates shadows (provided there isn't more than one light source) is reflected light bouncing into the shadow. This effect is stronger where there is more to bounce off of, so on flat ground there is very little source for this bounce, but closer to the walls there is more reflection possibility and so generally more reflection. In atmosphere, surface angle to the light also modulates the shadow intensity, but since the ground is roughly all at the same angle it's going to be uniform.

[whipstache]

Interesting. I'd always though shadows were darker the closer they got to corners because there was less area for the light to enter the space.

But, what you're saying makes sense. And the vocabulary you've used makes me think you probably know a thing or two about the subject.


So, as a follow up, how do factors that affect diffusion (like light cloud cover, say) have an impact on the uniformity of a shadow? Or just the density (and thus, hardness of the shadow's edge)?

[Falconius]

As you said they cause diffusion I think, which basically as I understand it, means instead of all heading the same direction the light is heading every which way, the more diffusion, the more it scatters. That's what makes shadows on an over cast day so much softer. The contrast would be space photos where there is no diffusion where the shadows have edges like a razor blade.
As for what I know, this is just what I understand of it from observation and more educated sources, I don't know anything about light sciences.

[Midgardsormr]

You're close in a few different ways.

Diffusion tends to become more pronounced the further you go from your shadow caster. So at the base of your building, the edges of the shadow will be relatively sharp. The further you get from the building, the fuzzier the edges will get. On a bright, dry day it may not be very noticeable. On an overcast day, or in a more humid environment, the effect is accentuated. The further the light travels from whatever is casting the shadow, the more diffusion can blur that edge.

Regarding shadow density near the base, you have three different things going on. First, indirect light bounce will indeed brighten areas that are close to one another and receive light. On the other hand, when the surfaces get very close together, they'll start shadowing each other, creating a darker area around where they're in contact (in CG we call this ambient occlusion). Finally, as you get further from the building, it occludes less of the diffuse sky light, slightly brightening the shadow the further away it gets. Here's an illustration:



Do keep in mind, though, that a map doesn't usually try to replicate physical reality. If it looks good, helps communication, and doesn't obscure other information, then it's correct. After all, the convention is to light shaded relief from the northwest, which is an impossibility in the Northern Hemisphere.

edit: For the sake of completeness, I want to also mention the terminator line, which is that transition area between the lit and shadowed sides and is darker than either. That only happens on round objects. It's the surface that is tangent to the sun's light rays, receiving no direct illumination, and distant from the floor, receiving less bounce light.

[Nikademis]

As others have mentioned, though not necessarily how light acts in reality, if it fits your personal style and conveys the message then its successful. I personally think it looks very sharp. Have you played with this technique on other objects?

There's some great information here in regards to light and shadows. I will definitely play with this in ps. Thanks all.