I've never heard of Bluesky but will find out who they are.
I'll bet the height is + or - 10 metres or so as well.
The accuracy of tree heights is probably rather good considering the volume
of data they are dealing
with, and the fact that a large part of the process is automated..so one lot
who did this counted
every tree within the M25. I expect it uses LIDAR which works on the
difference in return times of a
laser between ground and the top of the tree (and a plane from which the
measurement is taken).
As a side result I expect they could give us the number of trees in every
city that they have
surveyed. Puts TinT2 survey and estimates of stocking densities in towns back
in the stone ages.
Jon Heuch
Tel: 01233 713 466
mob: 07810 610 712
______________________________________________________________________
Greetings Forum. We are running a THREATS training day 19th August for two
local authorities & have spare capacity. The day will consist of training
in the use of THREATS, including advanced tree defect assessment,
comprising a mix of class & field work. Probable venue St Albans. Cost
dependant on numbers, but no more than £180 (exc VAT). Contact JFL or
Sally on 01767 641648 or email jfl@xxxxx.uk.com or baldwin@xxxxx.uk.com.
Booking will close 15th July @ 1200
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