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I have multiple sets of points that represent 'instances' of GPS traces. When ordered and connected, I have a line that represents each trace. I'm trying to find the most average line through this point cloud.

I've tried several approaches - the current one I'm working on is to put all the points together on the same layer in QGIS, and then run it through the SAGA 'Point filter' tool to remove outliers and select a core set of points. I then re-order them (I store ordering information alongside the lat/long of each point), and I end up with a set of points that pretty well represents the route.

Where I'm struggling is in understanding the QGIS parameters for the 'point filter' tool - I can make the parameters I choose work for some routes, but not others. I can't find any documentation on it and I don't quite understand what they do, which makes it hard to tweak them.

Specifically, what unit is the radius in? What does the attribute do? What do the minimum/maximum number of points do? What are quadrants? How does the tolerance affect the selected criteria? How does the tool choose what the maxima and minima are that it applies to tolerance/percentage to?

I've been changing these parameters myself, and haven't really been able to figure out what they do.

Has anyone used this tool before?

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