The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
Least squares adjustment 
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Grey Values 
Figure 3. Range accuracy for different grey levels (grey wedge) 
Figure 4. Range accuracy at day and night-time for different 
coloured sheets 
4.2 Intensity analysis 
The analysis of the intensity values has been based on the same 
measurements as those carried out for the geometric accuracy 
assessment (sect. 4.1). The results for the grey wedge clarify 
that the recorded laser intensity values - as expected - increase 
systematically from black to white but a certain non-linearity 
can be observed (Figure 5). The related standard deviations of 
the intensities also increase from black (MSE about ± 8 grey 
values) to white (MSE about ± 14 grey values) and therefore, 
show an opposite characteristic compared to the MSE of the 
range measurements. 
A similar behaviour can be obtained from the measured 
intensity values of the coloured sheets. The means increase 
from black, red, blue to green with somewhat higher values for 
night-time measurements (Figure 6). Also the MSE of the 
intensities (Figure 7) increase from black (MSE about ± 7 grey 
values) to green (MSE about ± 15 grey values) and confirm the 
results from the grey wedge 
Figure 5. Mean intensity values of different grey levels (grey wedge)