The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
calculations are clearly below those of calculation a) and b). 
This fact confirms that convergent laser scanner positions 
processed in a bundle adjustment help to increase the accuracy 
of object points. Moreover, the consideration of one fisheye 
image on each laser scanner position (calculation e and f) 
results in higher accuracies. The result of calculation g) and h) 
is slightly better, due to an even better overall intersection 
geometry. 
Scans/ 
Images 
Observ./ 
Unknown 
Points 
X 
RMS (mm) 
Y Z 
XYZ 
c) 
2/0 
318/178 
53 
1.20 
1.16 
1.43 
2.20 
d) 
2/0 
306/ 172 
51 
0.97 
1.00 
1.22 
1.85 
e) 
2/2 
605 / 239 
66 
0.66 
0.55 
0.88 
1.23 
0 
2/2 
585 /239 
66 
0.61 
0.60 
0.67 
1.09 
g) 
2/2 
580/239 
66 
0.62 
0.57 
0.79 
1.15 
h) 
2/2 
582/239 
66 
0.54 
0.49 
0.68 
1.00 
Table 2. Bundle adjustment results (configuration c - h) 
The results allow for the statement, that it is reasonable to use 
additional images in a combined bundle adjustment, in order to 
achieve a higher accuracy in terms of registration and 
instrument calibration. This applies particularly to fisheye 
images since they often cover the same field of view as the laser 
scanner. If the camera is actually mounted on the laser scanner, 
it is simple to use their images in a combined bundle adjustment, 
since an approximate orientation with respect to the laser 
scanner is already known. 
4.4.3 Multiple scans from the room corners 
In order to demonstrate the potential of the combined 
processing, observations of further scans and fisheye images 
were additionally introduced into the bundle adjustment (Figure 
7). For this purpose, at first i) 4 and j) 6 laser scans were 
adjusted separately as well as k) 4 and 1) 5 fisheye images as 
comparison. Calculations m) and n) combine the laser scans and 
fisheye images in an integrated adjustment. 
O 0 
< > 
r V V 
k) - 
£ 
m) ^ 
% 0 
A > 
£ 
g 
e • 
K» 
m 
j) ' f * 
‘ x* y 
1) - 
„) : * * v 
Figure 7. Configurations: multiple scans from the room 
comers 
Applying configurations i) and j), which only use laser scanner 
observations, a slightly better accuracy (RMS of estimated 
standard deviations of object point coordinates) was achieved in 
comparison to calculation examples k) and 1), which only use 
fisheye images for the 3D object point determination (table 3). 
But from table 3 it becomes obvious, that the combination of 
both leads to a significant improvement of the accuracy of 
object point coordinates. Calculations m) and n) show the 
potential of a combined processing of laser scanner and fisheye 
image observations. 
Scans/ 
Images 
Observ./ 
Unknown 
Points 
X 
RMS (mm) 
Y Z 
XYZ 
i) 
4/0 
696 / 223 
64 
0.53 
0.54 
0.63 
0.98 
j) 
6/0 
1014/245 
66 
0.47 
0.51 
0.64 
0.96 
k) 
0/4 
472 / 232 
66 
0.75 
0.72 
0.59 
1.20 
1) 
0/5 
568/238 
66 
0.64 
0.57 
0.63 
1.06 
m) 
4/4 
1157/263 
66 
0.29 
0.30 
0.40 
0.58 
n) 
6/5 
1534/285 
66 
0.28 
0.27 
0.36 
0.53 
Table 3. Bundle adjustment results (configuration i - n) 
4.5 Calibration results 
An advantage of the processing of observations in a bundle 
adjustment is the possibility of self-calibration. This means that 
the used measurement device (laser scanner and/or camera) can 
be calibrated simultaneously, since the calibration parameters 
can be handled as unknowns in the same procedure. This was 
applied successfully in the calculation examples presented 
above. 
Table 5 shows those laser scanner and camera calibration 
parameters, which could be determined significantly from the 
calculation examples j), 1) and n). While j) and 1) consider laser 
scanner and fisheye lens camera separately, calculation n) 
integrates both in one calculation. In addition to the parameter 
values their estimated standard deviation and significance level 
(in brackets) is presented. 
Concerning the laser scanner only a few parameters could be 
determined significantly: The sine coefficient of vertical circle 
eccentricity (c/) is most significant in calculation j). The 
horizontal and vertical collimation axis eccentricity (b 5 , c 3 ) 
could be determined on a 99% significance level; their 
significance was increased in calculation n). While the trunnion 
axis error (b 2 ) and the vertical circle index error (c 0 ) could not 
be estimated significantly at all, the collimation axis error (6/) 
was determined on a very low significance level. Additional 
parameters for the compensation of distance errors (offset a 0 
and scale ai) were included, too. Due to a high correlation 
between the two parameters, their significance is low. It might 
have been reasonable to omit one of both. 
Also fisheye lens camera calibration parameters (interior 
orientation and additional parameters) were estimated, although 
not all of them are presented in table 5 (lens distortion 
parameters are rather uncritical herein in terms of correlations). 
The standard deviation of the principal distance c and the 
principal point coordinate y 0 ’ could be improved in calculation 
n). The same applies to most of the additional parameters 
(distortion, affinity and shear). 
It can be summarized, that the integrated processing of laser 
scanner data and fisheye image data (calculation n) results in 
calibration values, which have a higher accuracy and 
significance in comparison to calculation j) with scanner data 
and 1) image data separately. That means that scanner and 
camera aid one another successfully in the self-calibration 
process. 
1041