HOW TO OPTIMISE THE RECORDING OF GEOMETRICAL DATA AND IMAGE 
DATA FOR THE PURPOSE OF ARCHITECTURAL SURVEYING 
Michael Scherer 
Ruhr-University Bochum, Geodesy in Civil Engineering, 44780 Bochum, Germany - michael.scherer@rub.de 
KEY WORDS: Positioning; Laser scanning; Photogrammetry; Engineering survey; Low cost technology; Architectural surveying; 
tacheometer; Totalstation 
ABSTRACT: 
In architectural surveying it is much more effective to closely integrate different surveying methods than to use them side by side. 
Based on this experience, new hardware and software as well as corresponding new measuring tools were developed. The hardware 
is based on a notebook-directed robot-tacheometer capable of reflectorless measuring, making it possible to run various new 
measuring functions, for example precise tacheometric scanning. This type of instrument is also called an intelligent tacheometer. 
Various surveying technologies were developed which are all based on control circuit mechanisms: The ability to traverse feedbacks 
distinguishes the active, object-oriented robot-totalstation fundamentally from the passive, not object-oriented laser scanner. 
In combination with an additional digital camera, the instrument may be used in a lot more possible ways. I. c. it offers the 
possibility to direct the instrument's telescope by mouse clicking on a photo being displayed on the notebook's screen and to exactly 
measure the coordinates of the point indicated by the cursor. In this operation-mode the image may be taken from an arbitrary 
position. This technique makes it quite easy to do online rendering or to establish a virtual model. 
1. INTELLIGENT SCANNING WITH 
TACHEOMETERS 
The “intelligent” tachcometer is characterized by the possibility 
of setting out directions computer-controlled via servo-assisted 
motors and to measure the distance to the object. The first 
reflectorless measuring instrument of this kind was developed 
at the Ruhr- University Bochum, Germany and presented in 
1994 (Scherer, 1995); now the companies Leica and Trimble 
sell a whole range of such devices with varying specifications 
(see fig. 1). 
For this type of instrument, various surveying technologies 
were developed which are all more or less based on control 
circuit mechanisms: The ability to traverse feedbacks 
distinguishes the active, X object-oriented — totalstation 
fundamentally from the passive, not object-oriented laser 
scanner. Special techniques to determine single points, points 
on spacial curves and points on surfaces are used. 
Intelligent scanning is opposed to the undifferentiated scanning 
with a laser scanner, where millions of points are taken, but a 
single point is without importance. Laser scanning does not 
immediately take the object into account. The instruments are 
still very expensive, the factor between time on site and time in 
the office varies between 1:10 to 1: 30. Often an additional 
tacheometer is needed to establish a coordinate network. And it 
might also be taken into account that the tacheometer is the 
most universal surveying instrument usable for many differnet 
tasks and not a special construction like the laserscanner. 
In chapter 2 different functions of the work with an intelligent 
tacheometer are described. Chapter 3 gives an impression of the 
enhancement of the large spectrum of possibilities when digital 
photos are added. 
  
  
1. Hardware : 2. Software : 
Robot-Totalstation plus 
notebook plus digital camera 
Program TOTAL of Ruhr- University Bochum 
  
  
  
  
  
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7 | N. 
K | À 
general survey -| | | grafic functions and 
ing functions | image processing 
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Y 
  
  
special functions for 
architectural surveying 
  
  
  
  
JTAL= Tacheometric Cbjectoriented Partly 
(Teil) Automatic ! asersurveying 
  
  
  
  
  
  
| 3. New methods: special , often completely new proceedings W 
  
Figure 1: Characteristics of intelligent scanning 
2. SPECIAL FUNCTIONS OF THE INTELLIGENT 
TACHEOMETER CONTROL OR: WHAT LASER 
SCANNERS ARE NOT ABLE TO DO 
Figure 2 contains a summary of various surveying technologies 
for the "intelligent" controlled individual point recording. One 
of these tools will be introduced or exemplified. 
  
     
   
   
  
  
  
  
   
  
  
  
   
  
  
  
  
  
  
  
  
   
   
  
    
  
  
  
   
  
   
  
  
  
  
   
   
   
  
  
  
   
   
  
    
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