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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part BS. Istanbul 2004 
  
  
| recording points of different types 
  
  
| special scanning | 
scanning surfaces 
  
  
      
  
     
     
line- scanning 
  
  
  
  
vertical horizontal | individual || object- 
profile profile pattern adaption 
  
  
  
  
  
  
  
  
  
  
  
  
automatic continuation 
of profiles 
  
  
single point 
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
di- in - control circuit setting 
rect direct image- out 
B tacheometer 
edge, manual extrapo- point seeking 
corner proceeding || lation- rod by intersec- 
point tions 
  
  
  
  
  
  
  
  
  
  
  
  
  
Figure 2: What laser scanners are not able to do 
Measurement of horizontal and vertical profiles 
When documenting monuments the profile-measuring function 
proves a very powerful tool, making location-independent 
horizontal and vertical profiling possible. Vertical or horizontal 
profiles arc taken absolutely independent from the position 
where the totalstation is stationed. They are automatically 
continued everywhere in the monument e.g. on both sides of a 
wall. Further useful tools, like initiating measurements out of 
the graph shown on the screen of the notebook enable fast, 
effective work. In practice the steps are: define the plane of the 
profile, determine the thickness of the slice in which the profile 
points should situated — i.e. 5mm- , and define a fixed distance 
between the points, independent from their distance to the 
totalstation - i. c. 3 cm. 
Recording of surfaces 
On this particular functionality the totalstation and the laser 
scanner have the most similarities: there is no differentiated 
selection of the measured points, but merely a polygonal 
seperation of the measurement area with subsequent automated 
measuring of the matrix points (see figure 3, 4). The steps in the 
practice using this function are: define the area by surrounding 
it with the laser point, determine the grid density; then the point 
positions to be measured is computed and the coordinates are 
automatically determined. 
Figure 3 shows a bust scanned with a small ray diameter. 
  
  
surface model(via 
programm Surfer) 
  
  
  
Original set of single points 
of the face 
   
e 
  
Figure 3: Scanning a small object 
In some cases the accuracy exceeds a laser scanner. In general it 
does not matter that this method needs more time, because the 
totalstation operates automatically. It is not required to measure 
an unnecessary high amount of points because a variable point 
density can be set according to the quality of the surface. Thc 
intelligent scanning can be further enhanced through automated 
recognition of the normals of surfaces to reduce the amount of 
points and to increase the quality of the points by considering 
the slope of the object. Another possible enhancement may be 
through automated distance correction for signals of variable 
intensity. 
  
  
  
Grid-model of 1600 automatically measured points 
Figure 4: Scanning a large region 
Figure 4 shows the scan of a larger region, but with points at 
greater distance. Both examples show that scanning with thc 
tacheometer might be a low-cost alternative to typical laser 
scanning. 
Precise determination of edges and corners 
Due to the fact that the diameter of the footprint of the laser 
beam measures only one centimeter, edges cannot be otherwise 
determined with high precision (figure 5).