[Award Winner] Structural Shadows in Photoshop

[paradox_wanderer]

Here's where you get to make a decision. Do you want to take the easy way or the pretty way? I added a texture to the background for giggles.

Easy way: See Figure 3a. Select the area between the rays. Apply a radial gradient (Black to white with the center balance at 75% to white, look at the gradient picture.) that starts at the center of the column and extends out as far out as you think your shadow should go.

Pretty way: See Figure 3b. Generate a profile of the collision object from the point of view of the height of the light. It can get rather complicated, but if you take your time, you'll have excellent results. As you can see, I didn't really take my time with my profile. I find it most beneficial if you can stick to paths in lieu of the raster masks. Using free transform, position the profile to line up with the shadow extents. (See Figure 4b).

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After you have the shadow in place, change the blending type to something more appropriate. Multiply or one of the Burns. Stay away from the Light section as it tends to alter the picture in the white section as well as the black, and we don't want that.

[paradox_wanderer]

Now it's time to soften the shadow. As it stands, it's not exactly attractive.

Easy: Select the area around the shadow (Go bigger then the rays, you'll need to have space for the blur to work.) Try to start one corner of the selection box or area exactly on the column. We're going to be using the radial blurs and it's mighty difficult to try to position the center of the blur in the exact location. The program interprets the extents based off page and/or selection. Hence the effort to try to make the column one of the corners of the selection. Apply a radial spin blur (I used 10 px in the tutorial images) and move the origin of the blur to the column. Change the opacity of the layer to somewhere near 50% and boom! You have a shadow. (see figure 4a).

Pretty: Again with the complicated selection from the easy section. This time, however, apply a zoom radial blur first. It softens up the edges better. I used 10px zoom, and make sure to move the center to the column. Then apply the radial zoom and again, Boom! (Figure 5a) you have a shadow.

Additional tips:
if you're using the Sun as your light source, decide the angle of incidence and use that for every shadow angle. 45° shows up pretty well for most maps.
When using multiple light sources, make sure you calculate each light individually and in their own layers. That ensures darker shadows when they actually overlap.
Don't be afraid to futz with the edges with a blur tool to make it look exactly the way you want it.
If you have a shadow that continues out to infinity, skip the gradient and go with a solid black.

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Good luck. Sorry for the highly unstructured method of my tutorial. I find that design is fluid and sticking to numbers gets me in trouble. I intend this to be a general guideline. Like cooking, the best comes out of personal tastes.