[Therion] standard deviation and survey grade
Bruce Mutton
bruce.mutton at paradise.net.nz
Mon Nov 24 20:25:22 CET 2008
Seems OK as a start. Agree that the elevations are often less accurate than
the plan positions...
Just to clarify, are the values listed to be 2x sd (mean to 95% limit)
Or 4x sd (lower 95% limit to upper 95%)?
Bruce
-----Original Message-----
> What about 'position'? I don't think the BCRA grades have much to say
about
> these. (I'm sure we can make something sensible up)
First proposal could be:
GRADE; POSITION / HEIGHT error (95% confidence); comment
0 -- position unknown
1 1000 m -- rough estimate / memory
2 100 m -- GPS in bad conditions (canyons, foliage, SA), small-scale
map
3 15 / 45 m -- GPS, large-scale map
4 5 / 15 m -- GPS longer observation, distinct features on a large-scale
map
5 1 / 3 m -- GIS GPS
6 15 cm -- geodetic GPS, theodolite/total station, technical
nivelation
7 5 cm -- geodetic GPS, precise theodolite/total station,
precise nivelation
Martin
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