Map matching with sDNA?

Question

I have a series of walking traces that I need to link to a walking network. So far, the matching algorithms available as plug-ins for QGIS (Offline Map Matching, Assisted Map-Matching) have yielded poor results and are computationally too demanding. Another approach would be to build buffers around the traces and calculate the shortest paths representing the traces on the network within the buffers. I am wondering if sDNA could provide a solution here, as the start and end points could be used in an OD matrix to derive OD geodetics. I am aware that ArcGIS Network Analyst can do this, but I would like to stay with QGIS (or GRASS).

The crux with sDNA is limiting each OD geodetic calculation to the buffer of each origin-destination pair. Using the buffers of all traces would essentially mean using the whole network.

Any suggestions if and how this can be accomplished?

Answer 1

I managed a work-around using R GIS, an R loop and GRASS GIS (rgrass) v.net.distance to calculate shortest paths. The advantage is that this allows me to use variable buffer sizes and that the code works with new data and networks as well.