Enhancing Autumn Cinematography with the Power of After Effects 3D

This season I had the opportunity to do something I haven’t done in a while: seasonal nature cinematography! Depending on who you ask, nature cinematography can be inspiring, frustrating, calming, or anything in between. For me, it was an opportunity to combine some traditional filmmaking techniques with some After Effects magic. Using After Effects expressions, effects, and 3D camera tracking, you can turn your cinematography shots into entirely new, ethereal autumnal scenes! If you haven’t seen the video yet, check it out:

The first trick I thought of was using After Effects 3D camera tracking to add “god rays” to forest imagery. This volumetric trick allows you to render streaks of light appearing from in between branches, leaves, etc. to give your shots some atmospheric realism. We can get the origin of the rays to remain the same thanks to After Effects’s 3D features!

First, prep your footage. Get it into the lowest frame rate you’re comfortable with (shouldn’t be under 24FPS). Next, track your footage with AE’s camera solver. This is automatic, so it shouldn’t involve much more than just pressing the button, sitting back and waiting!

After the track is done, select the camera track effect in the effects panel, hover over the footage, and you’ll see some 3D markers. Right click on the spot in the image where the god rays would be coming from, and click “Add Null and Camera”. This will plop a null object right in 3D space where the light is coming from; scrub through the timeline and you’ll see it stays in the same spot. Perfect!

Now, how to get those rays? First, duplicate the footage layer, and apply a radial blur effect. Set it to a zoom mode and adjust the amount until you see a streaky semblance of your image. Then, alt+click on the center point icon (little target). This will allow you to write an expression to tell AE where to put the center point. We’re going to tell AE to use the 2D screenspace that corresponds to the 3D null object’s location. To do this, paste this code as the expression (but change the values for your footage):

src = thisComp.layer('Null'); // Enter the name of the Null you made
src.toComp([0,0,0]);

Next, we only want the streaks to show up when the part of the screen where the light is coming from is bright. Otherwise, the light is probably blocked by a branch, etc. We can tell AE to adjust the opacity of the streaky layer according to the brightness of a certain part of the screen! Alt+click on the “opacity” timer icon, and paste this code in as the expression:

area = comp("NameOfShot").layer("NameOfLayer");  //Enter name of your comp shot, and name of the layer.
sample = [960,260]; //This is the location in the image you want to sample.
sampleArea = [50,50]; //This is how much area around that target you want to sample.
luminance = rgbToHsl(target.sampleImage(sample,sampleArea))[2];
linear(lum, 0, 1, 50, 100)

That code will adjust the opacity according to the brightness of an area of the screen of your choosing. Finally, just change the blending mode of the streaky layer to “Add” or “Screen” so you only get the bright parts of the image, and (after a bunch of tweaking of values), you’re done! You’ll also want to add a “curves” effect to the streaky layer to control the sharpness of the rays.

I hope you enjoyed this little After Effects tip; we’re open for custom work, animation, visual effects and more! Visit www.newflightdigital.com for more info.