The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
Relative distance Standard error of the unit weight (m 0 ) 
in adjustment 
0-4 m 1.5 mm 
4-29 m 2.2 mm 
Table 4. Standard errors of the unit weight mo in adjustments. 
Figure 12 describes the sampling intervals used for the 
calibration measurements as a function of distance. A couple of 
gross errors in the sled movements were taken place during the 
measurements. 
Sampling intervals 
Figure 12. Sampling intervals at relative distances (0-29 m). 
6. CONCLUSIONS 
Periodic errors found in this study can be corrected with the 
error function calculated by Fourier analysis. 
Single measured errors of relative distances were always 
positive or close to zero and at maximum of about 10 mm (Figs. 
6 and 7). We noticed that errors included a constant error and a 
nonlinear error. Constant error V (see Eq. 2) with 10 cm 
sampling intervals (0-4 m) was 4.6 mm and with approximately 
45 cm intervals (4-29 m) 4.7 mm. According to the error 
function (Figs. 8 and 9) the largest error was about 8 mm. 
The wavelengths of periodic errors often correlated with the 
wavelengths of the modulation frequencies of the instrument, or 
their harmonics. The evaluated wavelengths of periodic errors 
for relative measurements with 10 cm sampling intervals (0-4 m) 
were 0.31 m, 2 m and 4 m (Table 2). For measurements with 
approximately 45 cm intervals (4-29 m), the wavelengths 
evaluated were 1.2 m and 25.6 m (Table 3). One reason for not 
getting equal wavelengths for both relative distance areas may 
occur because sampling intervals were different and 
calculations were made with relatively small data. Therefore 
errors, or inaccuracies in calculated wavelengths are possible. 
According to Lichti and Licht (2006) wavelengths of cyclic 
error terms of Faro HE scanner are 0.6 m, 4.8 m and possibly 
38.4 m, which correspond to one half of the modulated 
wavelengths. 
Future research is needed to find out the original causes of the 
observed periodic errors. Possible reasons include non-linearity 
of the electrical circuit of the phase measurement system, 
crosstalk phenomena inside the instrument or extra reflections 
between the target and the instrument. 
ACKNOWLEDGEMENTS 
The research described in this paper is part of the Finnish 
KITARA programme consortia project “Use of ICT 3D 
measuring techniques for high quality construction”. The aim of 
the programme is to strengthen basic research expertise in the 
fields of mechanical, civil, and automation engineering through 
the application of ICT. 
Authors are grateful to D.Sc. (Tech.) Jaakko Santala for 
planning the calibration method, Veli-Matti Salminen for proper 
technical arrangements, Lie.Sc. (Tech.) Petteri Pontinen, 
Laboratory Technician Antero Tihverainen and M.Sc. (Tech.) 
Dan Haggman who helped with the measurements and Prof. 
Martin Vermeer for quidance and advises regarding the applied 
methodology. 
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