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I have a set of polylines and a set of points that lie along or very near to the polylines, and I need a way to measure which points are connected to each other along the polylines, and what the distances between each point are. Having the results in a neat grid would be nice, but I'll take what I can get. I have the vague idea that I need to use GRASS or SEXTANTE, but I don't know where to go from there (then again, I didn't know what GIS was a few months ago). Also, I have access to ArcGIS, but I'd rather use QGIS if possible.

To clarify the data a bit, my polylines are waterways in the Talladega National Forest, and the points are beaver ponds that myself and my research professor sampled. The points are either on or very close to a waterway, close enough that Road Graph can use them. I also have an area estimate polygon for each point, if direct connection is needed. I know that some of the points lie on different waterways from the others, but I need an accurate and repeatable way to find those connections.

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