1

I have a DEM which I want to find a point with largest amount of visibility ,I know that viewshed leads to visibility from a point but how can I find a point with highest visibility ?

One way is to loop every pixel in my DEM and then calculate visibility for each pixel. but this is not a very clever method.

Is there any tools or Algorithms which I can use to achieve this goal?

I can use c++ to run the algorithm.

  • You can limit search to local maximumss – FelixIP Sep 12 '17 at 19:35
  • @FelixIP But not all maximums are the points with highest amount of visibility – Majid Hojati Sep 12 '17 at 19:55
  • Correct, but it will greatly reduce list of candidates. – FelixIP Sep 12 '17 at 20:07
  • @FelixIP humm, I had this in my mind but How can I find local windows size to search? – Majid Hojati Sep 12 '17 at 20:19
  • I'd start with very large and compare with something much smaller. I don't think you'll find much difference. Yes, a lot of iterations.. – FelixIP Sep 12 '17 at 20:36
3

The whitebox GAT software has a tool that does what you need to do (I think), its called Visibility Index. From the manual:

This tool can be used to calculate the visibility of all locations within an input digital elevation model (DEM)

Whitebox is an opensource tool so there is an option for viewing the underlying code. You should be able to work out from there how it works.

You can download Whitebox for free here: http://www.uoguelph.ca/~hydrogeo/Whitebox/

  • thanks very much for your help, I'll take a look at it and hope I can find some informations about the algorithm behind it – Majid Hojati Sep 12 '17 at 19:50
  • The developer of whitebox (Dr John Lindsay) is on here as WhiteBoxDev. He might be able to assist gis.stackexchange.com/users/35151/whiteboxdev – Ed Rollason Sep 13 '17 at 8:30
  • Thanks very much, It is exactly what I need but it simply loops over every pixel I want to find an optimized method, I'll ask Dr. Lindsay to find out more about it – Majid Hojati Sep 13 '17 at 9:18
  • Something that might spark some thoughts (this may not work and I haven't tested). Would a looping of that tool using a lower resolution than your DEM grid find areas of generally higher resolution that you could then feed into a more detailed analysis using those areas as locations? It would avoid looping repeatedly over redundant areas of a high resolution DEM. – Ed Rollason Sep 13 '17 at 9:21
  • So you mean we can some how divide area into bigger pixels and then select those area and test on real image? – Majid Hojati Sep 13 '17 at 10:01

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