Hi, My answer pertain to vector based road or river networks. Least cost and circuitscape are generally raster based analysis. Maybe you should post on a new email so we don’t mix up both topics. Cheers!
Nicolas > Le 26 août 2019 à 14:28, Falk Huettmann <fhuettm...@alaska.edu> a écrit : > > Dear all, > thanks indeed, > we want to optimize for the longest path, or the one with the most > habitat/pixels underneath, > or at least see all options. > It's opposite from 'minimizing'. > I am probably aware how it is computed, mathematically (=flip the > optimization), > but in case you already know or see a plug-in, or such tools and software > available please kindly advise. > > Very best and thanks > Falk > > PS There is a lot of philosophy showing how utterly poor those optimization > and mindless cost/benefit tools perform in real life (=Pareto optimum > described as a 'brutal racist' tool etc > See failures of Economy or when it gets applied to humans). > It's also utterly harmful for wildlife corridors (as wildlife then is just > EXCLUDED and MINIMIZED, > instead of maximized. Just think of Movement Paths for Elephants and computed > with > Least-Cost Paths, or Circuitscape. It's pathetic. That's why economic > developers and NGOs like those tools so much. > So instead here we are looking for other options and readily-available tools, > ideally. QGIS could be a good platform for that. > Thanks. > All of this has real-world implications (urban planning, road projections, > logistics landscape design, > national park design etc) > > >> On Mon, Aug 26, 2019 at 10:14 AM Nicolas Cadieux >> <nicolas.cadi...@archeotec.ca> wrote: >> Hi, >> >> Shortest path analysis can be done by counting the number of nodes >> (connections or intersections) or by using a distance variable >> (traditionally length). However, “length” can be anything. It can be any >> combination of factors. Therefore, if you can model the various factors in >> a single “length” variable, then you can find the best path for your model. >> Some algorithm will give you all paths to one point, some only the shortest >> path, and some will permit you to use a maximum cut off (ie max radiation >> absorption dose if radiation is part of the model.) >> >> Nicolas >> >>> Le 26 août 2019 à 13:43, Falk Huettmann <fhuettm...@alaska.edu> a écrit : >>> >>> Dear Kind Colleagues, >>> >>> thanks, I have a similar question, but with an opposite aim: >>> >>> We have two points, >>> and want to connect them, >>> but then, NOT with the most direct and shortest path. >>> Rather, with the most meaningful and considerate one. >>> Like, >>> length is not to be penalized but other factors, habitats available, amount >>> of pixels >>> underneath etc. >>> Perhaps even showing different scenarios (aka, many paths lead to Rome...) ? >>> The path can consist of more than a line, an area connection let's say. >>> >>> So in other words: the optimization is NOT done by short distance. >>> >>> Would you have any ideas and suggestions on that ? >>> >>> Thanks so much for any input >>> Falk Huettmann >>> >>> >>> >>> >>> >>> >>>> On Mon, Aug 26, 2019 at 2:07 AM Chintan Advani <chintanadv...@gmail.com> >>>> wrote: >>>> Hi guys, >>>> >>>> I have a shape file with set of points on a road network. I am trying to >>>> find the shortest distance among these points using the shortest path >>>> tool. I have tried using the distance matrix tool in QGIS but it gives >>>> eucledian distance between these points whereas I am looking the path >>>> distance (based on road network). Can someone please suggest some tool or >>>> technique that can help me solve this problem? >>>> >>>> Thanks and Regards, >>>> __________________________________________ >>>> Advani Chintan Sanjeev >>>> Research Scholar, >>>> Civil Engineering and Build Environment, >>>> Queensland University of Technology, >>>> Brisbane-4000, Australia. >>>> _______________________________________________ >>>> Qgis-user mailing list >>>> Qgis-user@lists.osgeo.org >>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> _______________________________________________ >>> Qgis-user mailing list >>> Qgis-user@lists.osgeo.org >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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