The problem with having something tried and true is that every case really is different. It's possible to use tricks to pull this off but it will probably require a little bit of rotoscoping and clean background plates for your people to be over.
Using precomped gradient maps with the Gradient Wipe effect could help if you can divert the viewer's attention from the actual location of the wipe as it happens. If there are parts of the person that are in the same spot during a certain period of time, you can paint a gradient that moves through the motion of the person and wipes only when the parts are in a similar position.
You might also be able to use the Mesh Warp Effect to warp the parts of the person into the same locations at the time of the transition. Warp clip A to match a warped Clip B and then slowly unwarp Clip B back to it's original state.
Something that might help if you can get the imagery pretty close is setting the map for the Gradient Wipe to the clip you are transitioning to and feather the transition a bit. That does a great job with trees, wheat fields, water, and sometimes clouds.
Now, I bet there are others here who have used a combination of these or other effects to achieve the results you are looking for.
Of course, post your solution once you land on something so others can learn from it!
The methodology of making things seemless entirely depends on the content and without seeing it, nobody can advise. As Trent already indicated, corrective work may be necessary and sometimes a lot of it.
Here is a trick that I have used for creating seamless loops with difficult footage that has random motion. The short explanation is that you find a spot that you want to use as the start of the loop and make that the start of the movie by sliding it to the head of the comp and you use the out point of the bottom copy the new out point of the loop, then find a place in the middle where you can do a transition.
- Import a clip that is at least two or three times as long as it needs to be for your loop
- pick a point somewhere in the first 1/3 of the clip where you want the loop to start and split the layer
- move the clip on the right side of the timeline to the left so that the second half of the clip is the first part of the loop
- move the CTI down the timeline to a point where you think you can find a frame will provide a good transition point
- set the blend mode of the top layer to difference
- drag the bottom copy of the footage to the right until you find a frame where the overlap is nearly perfect
- trim the top clip's out point to the selected frame and set the blend mode back to normal
- set the work area to the outpoint of the bottom clip
- trim the comp to the work area
- nest the timed comp so you can apply time remapping or render the comp to a production format and import it so you can set the interpretation to loop
- if you decide to use time remapping then use the k key to go to the last time remapping keyframe
- move the CTI back one frame and add a new keyframe to time remapping
- delete the last keyframe
- add the expression loopOut() to time remapping
- extend the out point of the nested layer and you've got your loop
In this example I used a lens flair from a spotlight as my transition point
After setting the blend mode to difference and sliding the bottom copy I found this frame where the spotlight flair was almost completely black:
This is as good as it's going to get so I extended the top layer 2 frames to give myself a transition
After trimming the out point of the top layer and setting up a 4 frame opacity fade to hide the orchestra's movement and changing the blend mode back to normal I ended up with this:
I nested this comp in my main comp and applied time remapping as explained above I end up with a 10 second loop of the orchestra's big crescendo with the transition completely hidden by the lens flair from the spotlight. The audio track was cleaned up in audition and I was done.
I hope this helps. It's the only way I have found to create a visually seamless loop when you don't have a pair of perfectly matched frames. I have used this on waves crashing on a beach with great results but it took a lot of experimentation to make it seamless.
Thank you Trent. I am such a beginner that a lot of what you suggest is over my head in terms of navigating AE to implement these things but I do understand it in theory for sure. The simplest objective I have is how to clearly and easily identify the section of footage that contains the best possibility of a loop. It may not be perfect in the end but it will be the best possible in the footage. Then I see that work may need to be done (ie warp, etc). Would this be to duplicate the comp and changing the blend mode to screen or changing the opacity of the top layer and then scrolling through the bottom layer to identify the best section for a loop? I am basically taking a technique I use in Ps and somehow trying to apply it to video in AE. Lisa
Rick, THANK YOU! I do follow your instructions which are very clear. Now I am going to try it. I need to find a tutorial on adding expressions because I don't know anything about that and the same with "nesting"....that is completely foreign to me. I am going to see how far I get on this....thank you so much! Lisa
When you pre-compose layers you are nesting another comp inside the main comp. If you create your loop and trim it to the work area as I outlined then all you have to do is to drag that comp into a new comp that is long enough for your project, add time remapping, then go to the last keyframe, back up one keyframe and add a new one, delete the last keyframe, then Alt/Option click on the stopwatch and type in loopOut();
Then just extent the out point of the layer so you can see the video down the timeline. Nothing to it. By far the hardest part is finding a good section to overlap the shot so the transition is seamless.