[Inkscape-user] tracing lines from a bitmap

I want to trace a map from a bitmap, and using the built in tracing tools I get a reasonable trace. But I was wondering if there isn't a way to trace bitmap lines not as a path shaped as the outline of the bitmap lines, but as a single path going through the center of those bitmap lines. In other words, some kind of line recognition. I tried the edge detection, but that gives you two lines - not really what is required.

Thanks for any help.