[GRASS-dev] Re: [GRASS GIS] #390: r.viewshed precision bug

[GRASS GIS]

#390: r.viewshed precision bug
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 Reporter:  neteler     |       Owner:  grass-dev@…              
     Type:  defect      |      Status:  new                      
 Priority:  major       |   Milestone:  6.4.2                    
Component:  Raster      |     Version:  svn-develbranch6         
 Keywords:  r.viewshed  |    Platform:  All                      
      Cpu:  All         |  
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Comment(by hamish):

 Hamish:
 > tgt_elev=: how is that used if a target coord is never defined?

 never mind, I get it.

 > alternately, we could add r.viewshed in 6.x with a
 > wrapper script for the old r.los name, like r.cats ->
 > r.category.

 I'm liking this idea. [+ compatibility option for gr6]

 > any interesting coverage/patch map functionality
 > from r.cva which would be interesting to clean-room
 > reimplemented?

 fyi, r.cva:
 {{{
   r.cva draws heavily on the code for r.los, which was written by
   Kewan Q. Khawaja, Intelligent Engineering Systems Laboratory, M.I.T.

   *****

   PURPOSE

   1) Perform cumulative viewshed (CVA) analysis.

   OPTIONS

   1)  Record the number of cells visible from:

   all          every map cell;
   systematic   a systematic sample of map cells;
   random       a random sample of map cells;
   sites        a list of sites.

   2)  Record how often each cell in the map is visible from:

   all          every map cell;
   systematic   a systematic sample of map cells;
   random       a random sample of map cells;
   sites        a list of sites.

   3) Random sampling may occur with or without replacement.

   4) All types of sampling may be subject to binary masks such that:

      i)  Not all possible destination cells (cells to be `looked at')
          are of interest;

      ii) Not all possible viewpoints are of interest.

   5) It is possible to specify the height of the observer.

   6) It is possible to specify the height of the target object
      above ground.

   NOTE

   r.cva includes fixes for two bugs in the current version of r.los.
   These are that the observer elevation is cast to an integer, and that
   the patt_map does not effect the viewpoint and its immediately
   neighbouring cells
 }}}



 module options:
 {{{
 input: elev raster
 target_mask: binary raster map for target cells
 viewpt_mask: binary raster map for viewpoints
 sites: vector points layer
 output: raster
 obs_elev: ...
 target_elev: ...
 max_dist: ...
 seed: for rand num gen
 sample: sampling frequency as a percentage of cells  (default 10.0)
 type: {all,systematic,random,sites}
        all cells; systematic sample; random sample; sites map

 -f  calculate the `visibility from' rather than `viewsheds of'
 -m  differentiate masked cells from data value zero
 -n  treat sample size as no. of cells
 -r  allow replacement during random sampling
 }}}

 Hamish

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/390#comment:8>
GRASS GIS <http://grass.osgeo.org>