How and Why to Unsolve a Scene!

Under some situations, you need to UNsolve parts of a scene: when a solve goes wrong; or when the solver detects an error and says you must, after you've deleted too many trackers. A new graph editor channel, #Solved, shows the number of solved trackers on each frame, providing guidance and insight into the solver's operation.

Script for Search Engines:

Hi, this is Russ Andersson. You've heard me talk a lot about solving scenes, but today I'm going to talk about UNsolving scenes. We'll do that with the "Unsolve frames" script, which is enhanced for SynthEyes 2204, and guided by a new data channel, number-of-solved, in the graph editor. There are two main times when you need to unsolve parts of a shot: when you're solving a long shot, and the solve goes wrong, or when the solver tells you to as you start Refining. I'm going to demo with a long 360VR shot, but this tutorial is NOT 360VR specific. The shot is already tracked and partially solved. The solve went off the rails and stopped; let's see what happened, using the Graph Editor, and fix it. I'll turn on the camera's solved-frame channel, the number of valid trackers channel, the number of solved trackers channel, as well as the per-frame error channel. The number-of-solved trackers channel is the new one, it gives a lot of insight into solving. You can see where the solver has been working earlier and later into the shot, at around frame 9000. We need to identify the source of the problem. The Ricoh Theta S cameras are prone to lens flares that appear as a floating red dot. There's one around frame 8900 that caused the problem. We'll delete it. The solve in that area has been corrupted by that bad tracker; you can see its impact on the error curve. We want to remove the effect of that tracker, by UNsolving those frames. We'll do that now, using the Unsolve Frames script. We'll unsolve the last 200 frames from the end of the solved portion. And we'll require that any solved frame have at least 30 trackers, which is about half the 60 that they do on average. You can see how the solved region has been pushed back. Now we're ready to resume the solve. So that's the first, basic, use of Unsolve Frames. For illustration, I'm going to create a problem, then solve it. I'm going to unsolve all the trackers that are valid on this particular frame, creating a hole. If I start a Refine, I get an error message. At present, frames are labeled as solved, but they don't have any solved trackers on them. That's an inconsistent state that must be fixed. You can look at the curves in the Graph Editor to see where the problem lies. I'll address it by unsolving all the frames after this one. Now I can hit Go and the refine will proceed. In this last example, I unsolved the trackers, and showed how to recover and resume solving. But if I had deleted the trackers from the middle of the shot, I would have partitioned the shot into two completely separate pieces, where ANYTHING at all might have happened in between. That's super-bad, but that's what people tend to actually do, by over-deleting when trying to clean up a solve. It's difficult for SynthEyes to detect a partitioned shot when both parts have already begun solving. You need to be alert for it, and create additional trackers, or links between trackers in the different sections, to avoid it. So sometimes, UNsolving a scene is the best way forward to solve it. This is your developer, Russ Andersson, signing off. Thanks for watching.