I\'m trying to implement a polyline simplification algorithm. The original article can be found here: http://archive.is/Tzq2. It seems straightforward in concept but I don\'t un
I was confused by this too, went back and read the article again, and afaict it's not needed if you're removing points as you go - aka if you're doing a one-off simplification with a fixed area threshold. afaict the javascript implementation works this way, so it actually doesn't need the 'if' statement (but it has it anyway, oh well).
The 'if' statement is needed if you're keeping all the points around. In that case, you're storing the 'effective area' with each point so that later you can filter them, perhaps using an interactive slider that controls the # of output points. By storing that larger effective area, you preserve the proper ordering.