Full text: XVIIIth Congress (Part B5)

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SY BERUREING 
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three dats 
  
An effort was made to create the data sets in such a 
way that they approach closely nr imitate quite 
nearly the corresponding practical / live data. The 
true object space coordinates were perturbed using 
appropriate standard errors while assuming the usual 
normal distribution. Al other input data were also 
audified and/or perturked as necessary, The basic 
information used in simulating the data sets is chown 
in table !. The MEV Y-coordinates, used in deriving 
the corrections to computed Y-coordinates of non- 
control points, were perturbed for incorporating the 
random errors that are characteristic of practical 
data. 
The magnitude of the standard error used is tabulated 
in ites 4. The ‘Field Base' used in computing the 
photographic coordinates were perturbed using values 
of standard errors given against ilem 2 in the table. 
As regards pholographit coordinates, three major 
sources of systematic errors; the error in the 
interior orientation parameters, the error due ic 
Hils deforsalions, and error due to lens distortions, 
were considered. — The corresponding sean values and 
standard errors arg indicated in items i,2,and 4, 
sing these, two values were simulated for each one 
of the parameters & the first one was used to 
incorporate the source of error, while the second one 
wis used to counteract its effect, Bo, it is easy to 
see that the resulting photographic coordinates 
reflect the presence of  uncospencated residual 
systematic error effects, which is so characteristic 
of a practical! live data. The equations used in 
consideration of the radial and tangential lens 
distortions as recommended and used by Merchant, 
1972) and listed below, The data sets were used with 
9 MCV control points, equally distributed, in all the 
three planes, 
Br zo» Hb r2 6K2rd + 63 ré) PRL 
dyr = y Ui r2 € K2 r4 € K3 rh ) 5213.2] 
iisiPirze3232i € 22x yM 16€ Pu. 
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dut = 1 MPiny#P2 (r2 € 282 31H 1 foutu! 
vee iti) 
where, the subscripts — r and t refer to radial and 
tangential distortion effects respectively. Finally, 
the photoccordinates were perturbed far random 
Beaturement errport using indicated standard errors, 
401 
The data were analyzed on an JEN compatible PC, 
3, ANALYSES OF RESULTS 
The results chtained by processing the various data 
sets discussed in section 2 are summarized ang 
presented in table 2. RE already stated, three data 
sets were simulated and snalysed, For each dats set, 
three cases Ze, Jh and Jc with different casple sizes 
of 35, 7? and i were chosen, the first case Being a 
representation of the theoretical class, and the last 
one representative nf the typical pratiital cases in 
industrial phetogramselry, The comparison between 
the entries in items ! apd I gives the iagrovesent in 
quality which can be directly attributed to the NOY 
method. This improvesent expressed in percent 35 
averaged and shown against item 7, À comparison of 
the entries against itess 3 and 3 indicates the 
improvement im bias. This again is expressed at 
percentage and then chown az entries against iles 8, 
bias reduction. Finally, a rosperisen of entries 
against items © and & indirales the iaprovement in 
the standard error, This isprovemeni is against 
calculated as & percentage and chown ac entries again 
item 9, Thus, a Summary of the isprovesents gained by 
the use of the BOY method can be essily read by 
locking at the entries against items 7,8 and 5, 
Accordingly, il is essy to see that iaprovemenis of 
the order of &0X te 70% are generally achieves, 
However, it ic to be noted that 9? NOY control pointe 
distributed in the three planes, were used in 
achieving the stated improvement. 
5. CONCLUSIONS 
The conclusions are cusmarizes ss folioss, 
|j, The NOY technique is easily adaptable to the case 
of close-range photogrammetry. 
2, The reductions in AHS, Bias and Variante ere very 
substantial and hence worth the trouble, 
i, For the practical realisation of the method, it 
is essential for anyone io be able to invert the 
Variance matrix & 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996 
 
	        
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