I need to generate isochrones considering emergency vehicle’s speed. I have checked several packages in R and different plugins in QGIS. I found QNEAT3 (Iso-Area as polygons) as the only tool that the speed can be configured in but I am not sure if this plugin is the appropriate one in my case or not.
Selecting optimization criteria is mandatory in QNEAT3. It means that I have to choose shortest path or fastest path, while I just need to generate isochrones and it should be created using a feasible path for an emergency vehicle and I am not looking for routing optimization. My question here is that how does QNEAT3 works concerning one of these optimization criteria? Does it consider road network for creating iso-Area polygons or the iso-area polygons which QNEAT3 creates maybe be created through paths which a car could not traverse?
Another question is what is the difference between default speed and speed field?