compensation, and the correSponding process comes to a Stop.
3e A posteriori compensation of systematic errors
After T-testing had been performed, if T>1, it denotes
that sisnificant systematic errors exist, and a posteriori
compensation is needed to be done. Values of a posteriori
compensation of systematic errors for coordinates of all
model points based on corrections of svstenatic errors at all
tie points are obtained by using method of interpolation
(in this experiment both method of polynomial and weighted
mean values interpolation are used). With coordinates of
model points after adding the compensation values, next whole
block adjustment begins to carry out.
Formula /2/ used for polynomial interpolation is given as:
VU, =0 HA x Ha, xy a,01 aux y! +a,x"—a,x!y
Uy T bo byx t buy baxY t DAY + bsx¥* |+ box + byx?y
Va mOed Cx d C4 CX T 04! ex y! + cx + cy
where x,y are coordinates of model points.
a;» by and cg are coefficients of interpolation
When adjustment is executed by using individual model as
unit, the preceding 6 coefficients of interpolation are used,
When adjustment is made by double models, all 8 coefficients
of interpolation are adopted.
Formula /3/ used for interpolation of weizhted mean values
is:
Z3 (Z,D/ a
i=1
/3/
where d; refers to the distance between voint to be deter-
mind p and tie point i , Z4; is correction of SyStematic error
at tie point i, Zp is the correction of svstematic error at
point p sn is the number of tie point. When des 1,d; is
taken as 1.
III. Experiments on a Posteriori Compensation of Systematic
Errors
le Materials of experiment
For this experiment both simulated and practical data are
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ree ree = _