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I used a falloff shader as an atmosphere:
Escaping Gravity – 10 Tips for Photoreal Planets


INNER GLOW

The previous examples all use falloff to draw attention to the angles that turn away from the camera, enhancing the edges and sides of the object with highlights and reflections. But falloff is just as valuable a tool on the front-facing parts of your model.

Falloff can create an “inner glow” as if the light source is embedded deep under diffusing glass. It helps create the illusion of a point light within a translucent shape, as opposed to light emitting from an object’s surface. Useful for old fashioned light globes, pillar candles, street lamps, and mysterious tanks of glowing goo.





Falloff in the Glow Channel multiplied with a color

FAKE SUBSURFACE SCATTERING

You need to warm up skin tone but don’t want to wait for SSS to calculate. Simple: fake it with a falloff mixer. Similar to the Inner Glow effect above, copy/paste the diffuse map into the A and B slots of a shader mixer in your Glow Channel, set the image Brightness low in one, even lower in the other (I used 32% and 6% Brightness in this render). Use falloff to control the blending.



SSS is not only slow to render but difficult to control, changing drastically under different lighting conditions. But our fake SSS trick is easy to control. Here I’ve multiplied the front-facing glow with a fleshy pink color to warm up the dark skin tone. Works equally well to warm up light skin shades too!



Fake SSS Shader

BACKLIT HIGHLIGHTS

As you see, falloff can be used to isolate the parts of your model that face towards the camera as well as the areas that angle away from it, but it can actually do both at the same time. Here I’ve used a falloff mixer in the Highlight Channel and duplicated my specularity map with different Brightness settings. The appearance of “light wrap” becomes more pronounced with two separate settings for Highlight controlled with the falloff shader.



falloff defines two sets of highlights to exaggerate a backlit effect

GHOST

In both of the previous effects we’ve seen what looks like a lighting trick is actually done with shaders. Let’s take that idea a step further and ignore our scene lights altogether. Falloff in the Glow Channel with all other channels set to black or “none” creates an ethereal ghost effect Other uses include X-rays and electron microscopy where images are similarly created without the visible light spectrum. This render requires no scene lights at all!



TOON

Applying that same idea to the front-facing polys while allowing the falloff angles to be dark creates a false sense of “depth shadow”. Using only the Color Channel (with help from another DCG plugin SHADERS PLUS), we can create semi-dimensional toon shaders that don’t look “flat”. Again no lights in our scene means very fast rendering. Here the character’s skin, shirt, and even the hair have a pleasant cartoon-look without resorting to outlines or flat shadows – no lights necessary!

Hopefully I’ve given you some ideas of how to improve your renders with a falloff shader. Nearly any scene can be enhanced with falloff whether your goal is photorealism, illustration, or graphic design. Falloff increases the perception of depth on your models by exaggerating shadows and highlights, even creating the illusion of depth regardless of the lights in the scene.

Good luck, and happy rendering!

LINKS

SHADER OPS by Digital Carver’s Guild
http://www.digitalcarversguild.com/plugin.php?ProductId=11

SHOESTRING SHADERS by Shoestring Graphics
http://www.des-web.net/html/shoestring_shaders.html

EDGE FALLOFF SHADER by Sparrowhawke3D
http://www.sparrowhawke3d.com/Sparrowhawke3DLaboratory.html