After Effects - Light Transmission

Taking steps into 3d animation taps your imagination. Allow light transmission to help you find your ‘inner artist’.

There is a very simple, very cool technique in After Effects which allows you to play with color, light, and shadows.

There is a combination of three settings, one on the object receiving the image, one casting the image, and the light which produces the image. This is one of those effects that is so easy to capture, nominal learning curve, yet really impressive results right away.

Any catches ? Not really. There are always surprises and other factors and like any new technique your comfort level comes with a wee bit of practice. Like so often, my first experience was getting it to work, then not being able to reproduce it thoughtlessly. This technique is so simple there are only a couple issues, so let’s take a look.

When I’m learning something new, I want to isolate any settings that ultimately affect one another. I also want to keep it simple. Include objects that you need to define and test your new technique and no others. This prevents the introduction into your composition of anything ‘other than’ the objects, technique, and effects you are proving. Once you see and verify exactly what produces the effect you want, what may vary or skew, then bring everything back into the larger context of a composition where you are actually going to use this technique. If you have issues, you can go back and forth with the certainty that it works, that certain parameters are necessary and separate this from everything else in your composition.

If this sounds a bit wordy, this is a better real world example, just for the effect I’m sharing here. I chose a stained glass image, brought in a textured backdrop. Created 3 surfaces, one behind and to the right and left of this stained glass. On stained glass (which is a .jpg file type), turn on ‘Casts Shadows’ and move ‘Light Transmission’ to 100%. You can leave all other settings at their default.

On the backdrops, mine are image files but they could be simply solid settings within After Effects, turn on ‘Accepts Shadows’. Now create a light, setting it’s ‘Cast Shadows to ‘On’. That’s really it. When I didn’t always see color shadow right away, I began to play with the orientation of the stained glass.

Just as in real life, the relationship, distance and angle between the light and the glass in reference to the surface receiving the shadow make all the difference. Play with th orientation of the surface receiving the light, in my case the stained glass. However, one of the most fun discoveries is that while glass, and especially stained glass allow light to pass through creating a colored shadow, After Effects is simply obedient software.

If the object you want to ‘Cast Shadows’ is a picture, or a movie, or quilt, or even yourself, After Effects will obey. Just because you don’t transmit light doesn’t mean you can use this setting in After Effects. Use it on a picture, clothing because any object you define to ‘Cast Shadows’ will and it will transmit it’s color, just like a stained glass.

It helps to play with the settings that make this work: ‘Cast Shadows’ on the receiving object, ‘Receives Shadows’ on the accepting surface, and ‘Casts Shadows’ on the light. Besides these ‘on/off’ settings, adjusting the ‘light transmission’ setting on the object which cast shadows, and the light intensity of the light brighten your new image.

Experimenting with the positional relationships of all three objects may be the best way to see the varied results. Once you are comfortable with the settings, that produce these results, experiment with the relationships, angles, and distances just as you would in a movie settings.

This is a lot of fun and produces 3D results with brilliant color on your first efforts.