International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
4.2 Object space
Due to simulated systems with non-real values the evaluation of
the systems interior and exterior accuracy is based on the
assumption that the simulated values vary within their standard
deviation and therefore each random modified bundle
represents a possible real bundle configuration. The systems
exterior accuracy is represented by the error of length
measurement (LME) of distances with respect to calibrated
reference scales. The particular characteristics of the LME
concerning the verification of optical 3D-measurement systems
are described at VDI/VDE (2000). With respect to the example
bundles, which are used for the simulation process and the
analyses, the following LME are based on the reference
testfield of our institute (Figure 11, interior cube).
Figure 11. Photogrammetric testfield
The cube contains within a range of approx. 1m? 14 reference
targets, which are calibrated by a CMM, therefore 92 reference
scales for analysing purposes. The accuracy of the reference
scales represented by 3D-coordinates XYZ resulted in
RMS xyz [Ref] = 0.015mm. With respect to the used camera
system (Kodak DCS 645 M, example Table 1) and the network
design an interior accuracy of one bundle can be expected as
RMS xyz [ObSp] = 0.040mm (7).
RMS, ,,,, = J[RMS(X)F + [RMS(Y)] + [RMS(Z)] (7)
(XYZ)
Because LME are influenced by both uncertainties, this results
to an expected range of LME of +601m for 1c, +120um for 26,
+180um for 30.
LMEof 196 simulations (60 images per bundle)
01 A. — MÀ - Mn - à d
0.08 +
* uw x
il t —— rr
distanc e [mm]
Figure 12. LME of 196 simulations
LME of 195 simulations with RAD VAR -mod fication (60 images p er bundle)
LME [mm]
=
&
e
=
-0.15 Eo eM A
distance [mm]
Figure 13. LME for 195 simulations (RADVAR-modification)
LME of input bundle (60 images)
0.080 + 4 Lu
0.060 + y
0.040 s : # & +
„+ +
rb TLE
ta ++ = Hi nete
& 9004 ; Le € fft. ES
= 002 43 200 an etek FET "aber 1200
-U. EAE A i E N
t PR ^3 t
AG Na
+ ET
-0.060 mr
distance [mm] %
Ja i D P Me ee ae
Figure 14. LME of 2 results and overlaid InputB LME
Figure 12 shows the resulting LME for 196 successful random
bundles of each 60 images. The remaining LME result within a
range of £100um. Regarding the simulated bundles considering
RADVAR-modification (Chapter 3) the LME result in a range
of £150 um (Fig. 13). Due to a high number of LME values the
differentiation and analysis within one comparative diagram
cause difficulties. Therefore 2 results (crosses) are exemplarily
illustrated in Figure 14. These two diagrams are overlaid by the
LME of the input bundle (InputB) that are displayed with dark
dots.
Summarizing the output values of the reference scales to a
histogram, subdivided into 7 equal classes, the distribution
results in an approximation of Gaussian distribution curves
(Fig. 15).
histogram of reference scales of 200 simulations
count of scales in class
1 2 3 4 5 6 7
histogram class x of 7
Figure 15. Histogram of reference scales
Due to the normal distributed input values this resulting
distribution was expected. Hence the simulation process works
properly for normal distributed random modified bundles. This
effect is confirmed by resulting normal distributed output
values for reference points with respect to the point of origin.
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