The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
precision is shown as Fig.8. The mean of STDr is 0.187 m. As 
can be seen from the table, the magnitude of range precision is 
outside the LiDAR precision specification (1 cr =2.5cm) under 
the target distance is less than 250m. So the range biases 
considered as a system error are introduced into the adjustment 
model. 
Target 
R max 
(m) 
R min 
(m) 
Rmean 
(m) 
STDr 
(m) 
1 
165.965 
164.763 
165.465 
0.187 
2 
161.701 
160.491 
161.197 
0.196 
3 
154.654 
153.650 
154.194 
0.182 
4 
151.929 
150.867 
151.420 
0.177 
5 
167.545 
166.665 
167.131 
0.185 
6 
162.828 
161.791 
162.247 
0.182 
7 
157.190 
156.210 
156.708 
0.173 
8 
153.740 
152.637 
153.229 
0.171 
9 
231.319 
230.257 
230.783 
0.230 
Table 1. Range results 
Range precision of Lab 
Range value (in) 
Figure 8. Magnitude of range precision for nine targets 
The scan angle results are listed in Table 1 with A max 
maximum scan angle value, A^m minimum scan angle value, 
Amean mean scan angle value, and STD a standard deviations 
of scan angle. The corresponding shape of scan angle precision 
is shown as Fig.9. The mean of STD A is 0.00067° .The result 
demonstrate that scan angle measurement is so stable that scan 
angle errors as mention in section 2 can be omitted. 
Target 
Anax 
(degree) 
Anin 
(degree) 
Amean 
(degree) 
STD A 
(degree) 
1 
1.402 
1.397 
1.400 
0.00063 
2 
2.502 
2.497 
2.499 
0.00071 
3 
3.701 
3.697 
3.699 
0.00068 
4 
4.701 
4.696 
4.699 
0.00069 
5 
1.401 
1.397 
1.399 
0.00067 
6 
2.302 
2.297 
2.299 
0.00063 
7 
3.601 
3.597 
3.599 
0.00068 
8 
4.701 
4.696 
4.699 
0.00069 
9 
-3.097 
-3.102 
-3.099 
0.00064 
Scan angle precision of Lab 
Scan angle(degree) 
Figure 9. Magnitude of scan angle precision for nine targets 
4.2 Discussion 
The mention presented in paper enables the estimate the 
estimation of errors over general surfaces. No distinct 
landmarks are needed to perform the adjustment either as 
control or tie points. Consequently, there are only little 
restrictions on its application, as the adjustment model is based 
on modeling the actual effect of the error sources on the 
geo-reference of the laser point on the ground. A system based 
approach enables modeling and consequently removing the 
actual effect of the error sources. Furthermore, inclusion or 
elimination of error sources as more experience is gained 
becomes easier to implement. Error modeling concerns 
identifying the system errors and modeling their effect on the 
geo-reference of the laser point. 
Least-squares offers a variety of possibilities for analyzing and 
testing the results. Tests can be performed to check if the 
residuals are randomly distributed, thus, if all systematic errors 
are removed. The estimated standard deviation of unit weight 
allows for proofing the correctness of the a priori assumptions 
for the observation accuracies. Measures for the internal and 
external reliability can be used for blunder detection and for 
accessing the geometry of the adjustment. They show how 
much single observations contribute to the estimation of the 
unknown parameters and how much a single observation is 
controlled by the other observations of the network. Blunders 
in the individual observations are not expected to be present, as 
they are detected during the plane search. However, the blunder 
detection in the laser point adjustment would reveal if planes 
used as tie-planes didn’t match. 
Re-processing the laser points with the corrections determined 
in the adjustment results in a geometrically correct point cloud 
of which the accuracy can be described by the standard 
deviations derived by error propagation. At each of the 
tie-planes the laser point accuracy can be verified, by 
computing the planes’ normal vectors through the individual 
laser points. This gives the residuals in all three components x, 
y, z together with the length of the normal vector, i.e. the 
distance of the laser point to the plane. 
Laboratory experiment is performed to analyse the range and 
scan angle performance aiming to the same target point. The 
magnitude of ranging precision and scan angle is computed. 
The ranging precision chiefly depends on the time 
measurement accuracy and the magnitude of S/N. The result 
can be considered as correction to the raw range-finder offset. 
Table 2. Scan angle results 
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