Ball hits a tree

[Dakota]

Originally Posted by MD Longhorn

I have a ground rule triple example. One field I used to umpire on was at a park. In right field, about 250 feet out, the ground fell away (downward slope) toward a ravine. If you hit it past a spray painted line out there on the ground, it was a ground rule triple. No fence on that part of the outfield.

Why wouldn't that just be a GR double for a ground roller or a HR if it cleared on the fly? What is special about a painted line instead of a fence that would mean this should be a triple?