[GRASS-dev] [GRASS GIS] #2820: v.surf.idw results seem seriously wrong and don't match r.surf.idw results

[GRASS GIS]

#2820: v.surf.idw results seem seriously wrong and don't match r.surf.idw results
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  Reporter:  lrntct   |      Owner:  grass-dev@…
      Type:  defect   |     Status:  new
  Priority:  blocker  |  Milestone:  7.0.3
 Component:  Vector   |    Version:  7.0.1
Resolution:           |   Keywords:  v.surf.idw r.surf.idw interpolation
       CPU:  x86-64   |   Platform:  Linux
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Comment (by annakrat):

 Replying to [comment:8 pkelly]:
 > Hi Moritz, Thanks for bringing this to my attention. Looks like the bug
 with the squared distance was introduced when support for powers other
 than 2 was added in r32957, and ported to GRASS 7 in r59107.
 > My original interpolation use case was image pixels from a ground-level
 camera view that had been perspective-transformed to an overhead view,
 resulting in highly uneven point density across the region. Without the
 indexing s.surf.idw (as it was then) could take hours to run. The
 following extract from my PhD thesis gives some of the background:
 http://www.stjohnspoint.co.uk/gis/idw.pdf (although at the Firefox built-
 in PDF viewer seems to have trouble displaying it; it's converted from the
 original PostScript).
 >
 > Paul


 Perhaps you could summarize your algorithm and we can put it in the
 manual. Currently there is almost nothing about the -n flag.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2820#comment:15>
GRASS GIS <https://grass.osgeo.org>