COMBINATION OF PROGRESSIVE GROSS ERROR DETECTION WITH ROBUST 
ESTIMATION ON A QUASI ON LINE ERROR DETECTION IN AEROTRIANGULATION 
Joao Bosco Lugnani 
Universidade Federal do Parana 
Curitiba - Parana - Brasil 
Edson Aparecido Mitishita 
Aerodata S/A.-Engenharia de Aerolevantamentos 
Curitiba - Parana - Brasil 
ABSTRACT 
This paper presents the results of a research conducted by the 
authors, seeking to improve reliability and efficiency in time and 
economy, when simultaneous off-line block aerotriangulation is 
performed. 
Frequently the conditions in which the simultaneous block 
aerotriangulations are performed, particulary in Brazil and probably 
in many other countries, sum up a great number of sources of gross 
errors that cause serious problems for the processing of the 
simultaneous block adjustment. These errors increase the processing 
time, cause doubts in the detection of gross errors, reduce the 
precision and reliability of the results. 
A set of algorithms and a system of programs were conceived and 
implemented to detect gross errors, progressively, on a quasi on 
line basis, as the measurements are conducted. The algorithm were 
developed, implemented and tested for both, bundle block and 
independent model aerotriangulation adjustment. 
The results of the tests showed great imprevements in time of 
processing, efficiency in the detection of gross errors and in 
reliability. Robust estimation was applied in some steps of the 
sequential detection to encrease its efficiency. 
1. INTRODUCTION 
It has been an area of attention of the Photogrammetric Community 
the problem of reliability of the estimated parameters of 
phototriangulation. Reliability is closely related to detection and 
location of gross errors, that affects also the processing time and 
cost. 
Progress has been achieved in this area during the last few years. 
Some methods like the Data Snooping [02], [03]: The Danish Method 
[08], [07]; the Step-by-Step, [01], [06]; and the On-Line, [09]; 
have improved reliability. Some of them bring benefit also to the 
saving and others bring heavy load of processing time. The 
combination of methods has also been implemented and tested [06], 
[04], with benefits for the area. 
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