Within QGIS I am trying to perform a surface analysis to show the part of the terrain that can be reached from one or more source points in let's say 1, 2 and 3 hours of walk on the ground. That is to determine the minimum accumulative travel cost from a source to each location on a raster surface (DEM), considering the actual surface distance as well as other horizontal and vertical factors (friction, slope, type of soil, etc.).
I am NOT looking for a least-cost path tool (that only considers two points), nor a network analysis tool (that uses a network of streets, and so on), and not even a simple buffer zone/Euclidean distance (that doesn't consider the slopes). I'd like to consider all the terrain around one or more sites, so that if the cost to travel between the points varied according to some characteristic of the area between them, then a given location might be closer, in terms of travel cost, to a different point.
I am attaching an image of a simple map I'd like to achieve that might help in understanding the issue.
I know that in ArcMap this task is done by the Path Distance tool (link), but I am not able to find any tool or plugin in QGIS, GRASS or SAGA. I found that the VARCOST in IDRISI should do the same (link). The problem is also that I cannot find the exact term to define such analysis, as many different names seem to be used at the same time: cost surface analysis? path distance? travel time analysis? cost distance? travel cost? catchment area? service area? cost allocation? ...
I am using QGIS 3.16.1-Hannover on an Ubuntu 20.04.1 LTS laptop.
