INTEGRATION OF A TERRESTRIAL LASER SCANNER WITH GPS/IMU
ORIENTATION SENSORS
J.Talaya, R.Alamus, E.Bosch, A.Serra, W.Kornus, A.Baron
Institut Cartogräfic de Catalunya (ICC), Parc de Montjuic, E-08038 Barcelona
talaya(dicc.es, ralamus(@icc.es, ebosch@icc.es, aserra icc.es,wkornus(@icc.es, abaron(@icc.es
Ths 17 — Close-Range Integrated Mapping Systems/Laser Scanning
KEY WORDS: Integration, Orientation, GPS/IMU, Terrestrial, Laser scanning
ABSTRACT:
airborne laser sensors but not with the terrestrial laser systems. The
usual way to operate a terrestrial laser is by scanning a scene while the sensor remains static. In order to cover the whole scene,
different scans can be combined by matching several common points, finally the orientation of the scene is performed by identifying
and providing coordinates for a minimum of 3 points. This procedure is very time consuming leading to a very low productivity. In
order to increase productivity the Institut Cartografic de Catalunya (ICC) has integrated a terrestrial laser scanner in a mobile vehicle
with the aim to operating the laser while the vehicle is moving.
Direct orientation of laser systems has been widely used for
This paper describes the integration of a terrestrial laser scanner with the GPS/IMU orientation sensors of a Land Based Mobile
Mapping System. The laser pulses are synchronized to the GPS time by using a modified PPS signal from a GPS receiver. In order to
transfer the reference frame from the GPS/IMU sensors to the laser sensor a number of calibration scans and control points are used
and the offset and misalignment between the laser and GPS/IMU sensors is determined. The results of the calibration procedures, as
well as accuracies and performance obtained by the integrated GPS/IMU/terrestrial laser system are presented in the paper.
1. INTRODUCTION 2. GEOMOBIL
During the last years the use of terrestrial laser scanners for In the first stage, the Geomóbil (see figure 1) integrated two
3D modeling has widely been expanded. These systems CCD cameras in a van to capture stereoscopic pairs of digital
provide direct measurements of clouds of points that are images and all the equipment required to georeference
illuminated by the laser. A terrestrial laser scanner generally directly the collected images. The van was developed as à
collects the data by measuring a complete scene while the modular system that should be easily upgradeable with new
sensor remains static. Thereafter, the scene has to be sensors. Hence, the Geomobil is composed of different
georeferenced by identifying at least 3 points on the laser subsystems: an image subsystem, a synchronization
scanner image and giving them ground coordinates. In order subsystem, an orientation subsystem, a power supply
a data storage subsystem and a climatization
to improve the productivity the ICC decided to directly orient subsystem,
the laser scenes by integrating a terrestrial laser scanner with subsystem.
a GPS/IMU (Inertial Measurement Unit) orientation system
in a mobile vehicle with the aim to operate the laser while the
vehicle is moving. That integration allowed a direct
orientation of the laser scene reducing dramatically the time
required to obtain a geocoded scene ready to extract
information.
The integration of airborne lasers with GPS/IMU orientation
systems has been widely used since mid 90's providing good
results and leading to a wide exploit of the airborne lidar
technique (Lindenberger 1993). However, terrestrial lasers
have not followed the same path and they are seldom directly
oriented by a GPS/IMU system.
The integration of the terrestrial laser with the GPS/IMU
sensors was done in the frame of the Geomobil project
(Talaya et al. 2004), the mobile mapping system developed
at ICC.
5 ttes M a e
Figure 1: Geomóbil system developed at ICC
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