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Least squares methods and some other related procedures 
may give solution to an important group of problems of 
photogrammetry and, generally, of survey and mapping, as 
for example: 
e network/block/joint adjustment; 
© surface reconstruction, form descriptors; 
e feature extraction and parsing; 
e image/map/object matching. 
Going further with the above said division of adjustment 
and interpolation/approximation problems of photogram- 
metry and, generally, of survey and mapping, first area col- 
lects: 
e on-line triangulation of images: spaceborne, airborne 
and terrestrial; 
e GPS data processing, automatic surveying (robotics). 
Prior to processing, it should be pointed out pre- 
processing of data collected by space photogrammetry tech- 
niques (SPOT, MOMS, SAR, ...), with due care, as well as 
in geodesy (e.g. GPS) and related sciences. 
As far as interpolation and approximation are concerned, 
one should remind a class of problems of photogrammetry 
and cartography, related to: 
e measurement devices (camera calibration and other 
systems and sensors) and secondary effects; 
e morphological features extraction, image/map/object 
matching; 
e DEM generation, orthoimage production and super- 
imposition; 
e image processing, analysis (classification) and under- 
standing (semantic interpretation). 
Note that these problems usually involve a large number 
of observations and parameters and, consequently, require 
the solution of large systems, i.e. systems with a large num- 
ber of equations and unknowns. For these reasons, because 
blunders, leverages and small outliers occur often in large 
sets of data, robust procedures (robust estimators, reliabil- 
ity analysis, ..) suitably provide for data preprocessing, 
testing and archiving. 
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Baarda W. (1968): A testing procedure for use in geodetic 
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Draper N.R., Smith H. (1961): Applied regression analysis. 
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Hawkins D.M. (1980): Identification of outliers. Chapman 
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Forstner W. (1986): Final report on the joint test on gross 
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Wicki F. (1992): Robuste ausgleichung geodätischer netze. 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996