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15. RESECTION MEASUREMENT
*
Nullification of calculation will result. The figure below describes
the better arrangement.
It is
best to avoid a situation where the unknown station (instru-
ment station) lies on the same circle a s the known stations (in the
case of
3
or more known stations).
0.:
Unknown station
(Instrument station)
0 . :
Known station
Note:
When calculating the instrument station coordinates by only
measuring the angles of
3
known stations, if a station i s on
the same circle a s the known stations, the calculated station
coordinate will differ from the correct data.
If this situation i s expected, the following action i s suggested.
1) If possible move the station to the near centre of the
triangle or
2) Observe other known stations which are not on the
circle or
3) Measure the distance of one of 3 stations along with the
angles.
*'
0
h
31
0
@
If the angle between 2 known stations is narrow, the observing
condition i s not sufficient to calculate the instrument station
coordinates. When the distances between the instrument
station and the known stations are long, it is difficult to deter-
mine that the angles are narrow thereby avoiding the instru-
ment station being on the same circle as the known stations.
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