into
und
ers
tes
1et
Boccardo, Piero
4, RESULTS ACHIEVED
The 3D model reconstruction can be easily performed thanks to the capability of the LMS-Z210 laser-scanner and the
good potentialities of the post-processing software. No problems raised during the surveys neither in the image
processing phase. The capability of the acquiring system to overpass glass surfaces (with high transmittance coefficient
and refraction index) could be annoying for architectural surveying, particularly for object distance misplacement (all
the features behind glass surfaces) and shift caused by the refraction coefficient.
In order to test the metric accuracy of the laser-scanner takings, a digital orthophoto has been generated; in a second
phase a stereo-restituted survey has been superimposed on the resulting image verifying the accuracy of the
orthoprojected façade (figg. 18, 19). The tested accuracy is not more than 3 cm for each surveyed element; some
discrepencies raise when height discontinuities are taken into account in the orthoprojection procedure, giving an
“eroding” photographic effect.
Figure 18 and 19 — Orthoprojected image (a zoom on the left) with the stereo-restituted survey (superimposed in
white)
4 CONCLUSIONS AND FURTHER DEVELOPMENT
According to the authors the impressive capabilities of laser-scanner instruments (in terms of effectiveness, user
friendliness and surveying time) can be the solution of a broad range of different problems in architectural
photogrammetry, but also when other target has to be surveyed (for example in the evaluation of quarries volumes, civil
infrastructures, and so on).
In addition, the cost of the laser-scanner (approx. 100.000 DM), seems to be convenient for the huge application
surveying spectrum; professional use (in particular if compared to standard total station price) could be mortgaged in
few years of activity.
Future studies should evaluate, in details, the metric accuracy of the system, in order to include this instrument class in
future surveying specifications, taking into account particular capabilities of the device (for example the high resolution
scan with doubled metric resolution)..
ACKNOWLEDGMENTS
We like to thanks for their kindness Mr. Johannes Riegl and Mr. Jürgen Nussbaum. Without their aid, these tests can
not be performed.
REFERNENCES
P. Waldhaeusl, A test object for architectural photogrammetry: Otto Wagner's Underground station Karlsplatz in
Vienna, in XIV CIPA International Symposium, 2-5 October 1991, Delphi, Greece, pagg. 247-251
Internet Web site WWW.RIEGL.COM
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 75