5 Replies Latest reply on Nov 27, 2013 7:32 PM by Todd_Kopriva

    How do I Animate a Mask


      I'm new to After Effects and I would like to know how to use a Mask properly.


      I have an intro that I want to haver transition to a piece of footage via circular motion starting from a circle that appears at the end of the intro and grows to engulf the whole screen. I'm under the impression that a mask will do the job just fine but the only problem is I can't seem to animate it for the life of me, there are no scale options availible and as such I'm confused as to how to proceed.


      I would also like to know if this effect would transition if I brought the footage into another project (in other words, does opacity function across rendering and importing), and how would I make a transition that fades the whole screen?


      Help would be awesome.

        • 1. Re: How do I Animate a Mask
          Dave LaRonde Level 6

          That's an After Effects 101 sort of  question, so I refer you to..... After Effects 101:

          Getting started with After Effects (CS4, CS5, CS5.5, CS6, & CC)


          Happy learning.

          1 person found this helpful
          • 2. Re: How do I Animate a Mask
            Greg Baber Adobe Employee

            If you push M the mask properties should appear - the one you want is "Mask Path"


            If you click the stopwatch icon in front of Mask Path, then any changes to the shape of the mask will be keyframed on the timeline.   Using the selection tool, if you hover over the control points, it can be moved where ever you want. 


            If you just want to change the size of the mask, there is a mask property available from the twirldown menu under Masks called "Mask Expansion"  Increasing that value will cause the mask to grow outside the current bounds.  Reducing it will contract the mask.  This property also has a stopwatch and can be fully animated.


            This property can be exported out of After Effects if you render out to a format that includes alpha values.  In the Render Queue, the Output Module has a drop down that allows you to choose RGB+Alpha - that will get the transparency you are looking for.  Not all formats support this, you may have to try a few different types.  On a PC, you can use AVI with the Lagarith codec, just make sure you go into the codec settings and choose RGBA (RGB + Alpha)  On a Mac, QuickTime Animation is a good choice.

            1 person found this helpful
            • 3. Re: How do I Animate a Mask
              kiheerSEDMAN Level 1

              Wow, thanks a bunch.


              How does one make the Mask appear halfway through the project?

              • 4. Re: How do I Animate a Mask
                Rick Gerard Adobe Community Professional & MVP

                Even easier hold down the Ctrl/Cmnd key and press M. This will set a keyframe at the CTI for the mask property. The same trick, pressing Ctrl/Cmnd + s or a or r or t or p will set a keyfreme at the CTI* for Scale, Anchor Point, Rotation, Opactiy, or Position.


                You could also turn on automatic keyframing.

                Screen Shot 2013-11-27 at 2.55.37 PM.png

                This will set a keyframe any time you change any animatable property. Some folks like this. It drives me nuts, but it is another option.

                • 5. Re: How do I Animate a Mask
                  Todd_Kopriva Level 8

                  Please, do follow the link that Dave gave. Animating a mask is covered in the first resource linked to from there.


                  It is very important to learn the basics.