Complications with having the Point of closest approach at the head of the track
In the event below we see that although the track crosses the tile plane far ahead of the head of the track, the POCA between the track and the tile actually happens at the head of the track. (The vector of closest approach is show in red, it goes from the head of the track to one of the bottom corners of the tile.)
Here is a 2nd example. In this one we can see how the POCA would actually occur somewhat behind the head of the track.
In the current version of the algorithm, we would actually report the POCA behind the head of the track. In the new version we do things the way they appear in these two sample event displays and show the POCA ot the head of the track.