[GRASS-user] Network Analysis Question

[Alec Ward]

I am a beginning GIS user attempting to use the GRASS plugin for QGIS to do a network service area analysis of roadmaps in Northern Ireland. I have encountered the following issue, and was hoping someone might be able to help me resolve it. I have imported the two shapeless containing the roadmap and the point I wish to use as the center node into GRASS and have connected the the point to the network using the v.net tool. I am now trying to use the v.net.iso tool to perform the service area analysis. In the GRASS tools dialog box for v.net.iso, I am able to select the network map I created using the “connect” function of v.net from the dropdown menu for “input arc” no problem. I am also able to set the cats and isoline costs. However, when I click on the dropdown menu for “input nodes”, nothing happens. The box highlights, but no menu appears, as if there are no files of the type eligible for that field available. I’m sure I’m doing something wrong, but I’ve read through all the literature I can find and can’t figure out what it is. Any help or advice would be very welcome.

Thanks,
Alec