I'm trying to create a an area that can be reached within a certain amount of time/distance from a single (or multiple) points. To do this i'm using the GRASS tool v.net.iso (via the GUI). I've succesfully made a Grass routable network with two layers (arcs and nodes) via the v.net tool.
The trouble starts when I want to use the v.net.iso tool. I select the input arcs and input nodes to be my created network. But than I have to input "cats (select from the map or using their id)" When I hover mouseover, it sais the following: "Categories of centres (points on nodes) to which net will be allocated. Layer for this categories is givan by nlayer option.
Do I just type the coordinates from one of the nodes? e.g. "xcoordinate|ycoordinate". Because if I do this, I get the following error: "Not enough centres for selected nlayer. Nothing will be allocated."
And can I let the cost isolines be dependant on an attribute? Or can I only manually enter the cost isoline in mapunits?