1. 44, No. 2, 
Bas, Hiiseyin Gazi 
  
THE ACCURACY OF USING THEODOLITE IN CLOSE-RANGE ENGINEERING MEASUREMENTS 
Hiiseyin Gazi BAS 
University of Sakarya 
Engineering Faculty 
Department of Civil Engineering 
Sakarya- TURKIYE 
Working Group V 
KEY WORDS: Engineering Measurements, Accuracy, Using Theodolite in Photogrammetry 
ABSTRACT 
Digital theodolites have been increasingly used in engineering measurements and industrial 
applications recently. In these applications the accuracy of object space coordinates is a function 
of the object distance, the base, and the measured angles with theodolites. In this study, a 
mathematical formulation has been developed to estimate the accuracy of object space coordinates 
when a theodolite as a measuring tool and the parallax equations of normal case of 
photogrammetry are used to compute the object space coordinates. Some tables related to data 
acquisition have been given depending on the main parameters which affect the accuracy of 
coordinates. 
1 INTRODUCTION 
In the current measurement technology, digital theodolites have been increasingly used in close 
range engineering measurements and theodolite measurements heve become a part of industrial 
application. This technique, called “combine method”, (Bas, 1993) is preferred to the close range 
photogrammetric technique used by Abdel-Aziz (1979). The basic features of the method consists 
of portability, non-contact, veriable geometry and automation. The simplest components of the 
system are a theodolite (traditional or digital) and calculator. A digital theodolite, a computer and 
suitable software are the best and most suitable components of the system. 
The engineering and industrial measuring areas in which this method has been applied require 
results with positional accuracies to within fractions of a millemetre. In addition to the 
instrumentation and software features of the system, the other components of the system are very 
important for achieving this high level of accuracy. Briefly the accuracy of the object space 
coordinates is a function of the elements of the system which are the theodolite used, pointing and 
centering the theodolite telescope to a targeted object point and the configuration of the control 
network. 
The most important characteristics of the theodolite in achieving the desired accuracy are reading 
precision and sensitivity of the level bubbles. The resolution of the theodolite angular measuring 
units is the initial limiting factor and currently available theodolites have resolutions of 0.3 
seconds of arc (0.1 mgon). The factor affecting the accuracy in the photogrammetric procedure 
such as limited format, image distorsion, and focal length are not present when a theodolite is 
used. 
Tests have indicated that under good conditions it is possible to achieve sighting precision of 1 
second of arc (0.3 mgon) with a single pointing of the theodolite (Grist, 1991). The configuration of 
the control network controls the geometry and the data acquisition of the method. The main 
geometrical factors which affect the accuracy are directions or angles measured with theodolite, 
object distance and the base. In addition to these factors, other secondary sources of errors such 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 45