Geoscience Reference
In-Depth Information
Worked Example 10.2 Trying triangulation
Figure 10.5 shows a topographical map of a
remote area with few landmarks where GPS
failure occurred. Locations had to be determined
by triangulation, using the few landmarks that
were visible and marked on the map. An initial
attempt at triangulation was made, yielding three
bearings to the three rather distant landmarks
listed in Table 10.3 (p. 216).
10
(a)
Figure 10.5
(a) Initial
attempt at triangulating a
location in a remote area
with few suitable landmarks.
The three plotted bearing
lines meet in a triangle of
error (shaded red), so the
location is not determined
very precisely. (b) Revised
attempt at triangulating the
location in (a). The fourth
plotted bearing line (green)
meets two of the previous
lines in a smaller triangle of
error, so the location is more
precisely - and accurately
- determined. (Base maps:
Ordnance Survey 1:25,000
Scale Colour Raster from
10 km grid square NJ(38)30
© Crown Copyright 2009.
An Ordnance Survey/EDINA
supplied service.)
(b)
