which are the differences in coordinates of the centroid mentioned
above and the inverse point of station I on the a-b coordinate
system, apart from a scale factor.
It is then seen that
V1 caAYi c^AXi w I \auAYi bijAXivai i vi p.
The law of propagation of errors applied to this gives in partly
symbolical notation:
1 n +(CaQvi CbQxt)2S2 (~1^) 2 V («I-iQy, +&I-iC)A'f)2 t
This relationship can be derived for the other stations II, III etc.
and also the covariances aFi„n, Gvivm etc.
One should avoid unnecessary complications of correlation by
omitting the occupied stations I, II, III etc. as mutual orientation
points in the field.
In order to minimize cr^i the orientation bearings (]>ishould be
selected in the field so as to reduce the distances ca and cj to a
minimum.
This term would be zero if the centroid of the inverse points of
the orientation stations i coincides with the inverse point of station
241
Inverse point of P
not on scale
b
Figure 2
i n l
i 1
(II)
i - n 1
i- 1
(I
