little perf tip: when using Barriers, Groups, etc constraint_referenced_tags is 1-2 orders of magnitude faster than constraint_referenced_ids. Quickly adds up for complex layouts.
A chart I put together a couple years back for a (rejected) Sloan paper.
Using SportVU data to compare typical "windup" motions for a player's three point shot.
Each dot on the chart is spaced 0.01 seconds apart.
1/