Boccardo, Piero
NEW METHODOLOGIES FOR ARCHITECTURAL PHOTOGRAMMETRIC SURVEY
Piero BOCCARDO,, Giuliano COMOGLIO*
"Politecnico di Torino, Italy
Dipartimento di Georisorse e Territorio
Boccardo@polito.it, Comoglio@polito.it
Working Group IV/2
KEY WORDS: Photogrammetry, Laser-scanner, DEM.
ABSTRACT
In recent years new survey technologies have been implemented in order to execute more accurate and effective
measurements. In particular, the investigation of architectural goods have imposed to take into account the
reconstruction of 3D models for more effective facade analysis and 3D navigation. For this purpose it is necessary to
derive an object digital elevation model (DEM) useful both for volume assembly and for digital orthoprojection
methods. Traditionally, a DEM surveying is performed by means of profiling topographic total stations, or derived by
photogrammetric stereoplotting. The aim of this paper is the first analysis of an automatic DEM surveying device
capable to acquire thousands of points in few seconds with high precision and accuracy. Following the CIPA test
conducted on Vienna Karlsplatz underground station designed by an art noveau master, Otto Wagner, a complete test
field has been conducted. This paper presents the first result of the above mentioned device, an optical-electronic laser
scanner.
1 INTRODUCTION
1.1 Laser-scanner state-of-the-art
In recent years a new technology has been implemented in order to reconstruct 3D models; this technology, based on
optical-electronic devices, uses an high intensity pulse directed toward the object to survey, in order to have a distance
from the device itself. From thousand of different pulses a digital image is derived where all the measurements
performable on single points are pure 3D locations.
Laser-scanners have been successfully mounted onboard of satellite and aerial platform first as telemetric devices
capable to define, in an indirect way, the spatial position of the platforms themselves; recently, aerial laser-scanner have
been mounted onboard of airplane in order to derive high precision DEM, being the precision independent from sensor
and target distance. Unfortunately, control points definition, useful for DEM-to-photogrammetric image warping, is
particularly difficult to determine because of the instability of laser-scanner rotating mirror and of the low accuracy in
determining projection center parameters without kinematic GPS.
No metric tests have been conducted on static laser-scanner before, where warping and photogrammetric taking
parameters could be derived in an easiest way. In $ 2 this approach will be deeply described.
1.2 Laser-scanner operating principles
The laser-scanner used, named LMS-Z210 is manufactured by RIEGL-Laser Measurement System located in Horn
Austria.
LMS-Z210 laser-scanner (shown in fig. 1) is a fully portable sensor, specifically designed for the acquisition of 3D
images. A rotating mirror directs the internal laser rengefinder’s transmit beam over a precise angular pattern. The
resulting range measurements comprise a very accurate 3D dimensional representation of the acquired scene. LMS-
Z210 device operates by any standard PC or notebook, measuring range up to 350 m, with a field of view up to
80°X340°. The scan time is approx. 30 to 240 s, with a nominal metric accuracy of + 2.5 cm.
Until now, the laser sensor has been used for 3D imaging of building and structures, topographic mapping of quarries,
mines and tunnels, scene acquisition for virtual reality modeling application and for dimensional measurements of
vessel, furnaces and tanks. The principles of operation are shown in fig. 2.
The range finder electronics (1) is based upon a classical laser distance meter, optimized in order to meet the
requirements of high speed scanning (fast laser repetition rate, fast signal processing and high speed data interface).
70 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000.
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