83
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When there is a known point not yet measured; perform measurement using the same procedure beginning with
step 3 in “Chapter 15. Resection Measurement.”
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When a known point is to be added, perform measurement using the same procedure beginning with step 1 and
2 in “Chapter 15. Resection Measurement.”
EXPLANATION
·
In some cases it is impossible to calculate the coordinates of an unknown point (instrument station) if the
unknown point and three or more known points are arranged on the edge of a single circle.
·
An arrangement such as that shown on the left is desirable.
▲
：
Unknown point
●
：
Known point
·
Sometimes it is impossible to perform a correct calculation
in a case such as that on the left.
When they are on the edge of a single circle, take the
following measures.
Move the instrument station as close as possible to the center
of the triangle.
·
When the distance between known points are fixed. When
distance between station point and known points are
increased, their included angle are lessened, the known points
can easily be on the edge of a single circle. It is impossible to
calculate the coordinates of the instrument station if the
included angle between the known points is too small.
16. Area Calculation
It is also possible to calculate the area of land enclosed by three or more known points on a line by manually
inputting or reading the coordinates of the points.
Coordinates(Known value)
：
P1 (N1, E1) Area (calculated value)
：
S
P2 (N2, E2)
