The subject for the second of our AfterEffets sessions was rotoscoping. We encountered this before with Jay in year 1, where we used Photoshop to draw stick men on top of a video of a break-dancer. This time we had to clip out a subject from a video using AfterEffects.
Originally I had found a highlight/promo video for a French water skiing festival/competition, I had intended to use a 4 second clip of a guy doing some back flips, but once I had imported the clip into AE the subject was too far away and the back flips caused too much disturbance in the water so you couldn't get a clear view of the jet ski to use this technique properly, so I scrolled back through the video and found a close up of a man doing some beat-boxing or rapping or singing into a microphone (there is no direct audio in the clip, its drowned out by the overlaid music track). We had to cut out a 2 second clip, that we could loop to fill out a 10 second long clip. We could speed or slow down how fast the clip could play be altering the time stretch setting, playing at 100% meant it played at normal speed, stretching it to a higher percentage would play it slower, and vice versa.
For the next step we had to change one of the preferences, we had to turn off "Preserve constant vertex and feather point count when editing masks. Using the pen tool we had to clip around the subject, creating a mask, to speed up this process we did this every other frame, by creating keyframes every 2nd frame. Because my subject was also holding a microphone I had to clip out the background which was visible through the gap between the mic, his arm, and this head. The idea was to use as little points as possible whilst still keeping a smooth appearance. To animate the mask path we tried to use as few key frames as possible, and moving forward until the mask didn't line up with the subject, and then moving the points of the mask so that they fitted.
To check that the quality of the loop was good enough, we had to test it. We did this by opening out the layer in the time line, opening out all the masks, selecting all the keyframes, and then ctrl + clicking them you can toggle the hold keyframe. Playing this with the loop playback option you should be able to see the quality of the loop.
Then we created the new composition which would be 10 seconds long and be the final product. We dragged the rotoscope assest onto the timeline. To make the clip last the 10 seconds we had to go to the layer menu at the top of the screen, go to layer, then time, and enable time remapping. This allows us to manipulate the speed that it plays at, as moving the keyframes together allows us to speed up the composition, and stretching them beyond the 2 second clip allows us to extend it to the full 10 second duration. The next step was to move the playback head to the end of the tieline and then move it to the penultimate frame and adding a keyframe here. We then deleted the last keyframe.
Once this was done, we then had to loop the two second clip to fill the 10 second duration. This was done using an expression (which we learnt how to use in the previous AE session). This was done by alt + clicking the time remapping stop watch, and then pressing the play button inside the circle allows us to open the expressions dictionary. We then selected property, 'loop out property (type=cycle, duration = 0), we then could drag out the layer to fill the 10 second. I then added a solid background colour and toggled the trackmatte option to see the video.
Rotoscop'd! from Matt McGough on Vimeo.
Given more time I would have liked to be a bit neater with the clipping and maybe add a different background.
