AE - Rotoscoping

Rotoscoping is the process of creating a matte or mask around an element in your video, very useful when it comes to moving objects. After Effects has a very developed way of rotoscoping that delivers great results. Here’s how to use it!

	Put the clip you wish to rotoscope on your timeline. Double-click it to go to the Layer View. You can ONLY work on rotoscoping your clip in the Layer View.
	Your program will now open the Layer View for the clip.
	Select the Roto Brush Tool from the Tool Menu.
	Left-click, hold and draw over the elements you wish to mask out. It doesn’t have to be very precise. By holding Option/Alt while drawing the selection, you can subtract from it (a red brush will appear, instead of green).
	There are three views available to make masking easier. ALPHA ALPHA BOUNDRY ALPHA OVERLAY
	ALPHA Lets you clearly see the separation between the masked object and the background, however makes it hard to make adjustments.
	ALPHA BOUNDRY A clear view of the selection using a pink border.
	ALPHA OVERLAY Puts a coloured overlay over the background, leaving the masked object visible. You can adjust colour and transparency using settings next to the button.
	If you’d like to get a more precise edge, you can use the Refine Edge Tool. Select it and drag over the already existing selection. It will create an alpha channel area that shows the separation of the object. You need to have a basic Roto Brush selection to be able to use the Refine Edge Tool. It’s a great tool to deal with masking hair!
	You can change the size (diameter) of the brush in the Brushes panel for easier coverage.
	Once you’re happy with your selection click on the Freeze button to activate and track the mask. Once the Freezing process is finished you can scrub through the timeline to see the selection. If you wish to adjust your selection, you need to once again click on the Freeze button to unfreeze and update.
	Once you’re happy with your mask, you need to go to your Composition panel to view the final result. You can toggle the transparency grid (checkered background) on and off with the icon below.
	In the Effects Controls Panel you can adjust various settings for your Roto Brush and Refine Edge. Play around with those to achieve best result.
	Now you can put whatever you want underneath your main video layer and it will appear behind it.