Implantation et évaluation de la performance d’une méthode d’ajustage en mode statique des systèmes lidar mobiles terrestres

Authors: Ndir, Papa Médoune
Advisor: Larouche, Christian
Abstract: Nowadays, the Mobile Lidar Systems (MLSs) are used in a multitude of professional disciplines related to territory mapping. Following the example of Mobile Mapping Systems (MMS) based on photogrammetry, a ground-based MLS oers an interesting potential by allowing the geospatial professionals to be more ecient at carrying out routine measurement operations with a complete portrait commonly known as a "point cloud". From a mobile terrestrial (road vehicle), airborne (drone) or marine (ship) platform, where a navigation system (INS-GNSS) combined with one or several laser scanners are xed, the MLS allows the acquisition of 4D (x, y, z, t) geospatial data with a high level of precision and detail. However, the integration of these sensors of dierent grade and utility requires a procedure for control and validation of the integration parameters to improve the added value of the point cloud. The integration parameters of an MLS are: boresight angles, latency and lever arms. The boresight angles are the three relative orientation angles between the scanner frame and the IMU frame. They are one of the major sources of error that must be tackled in order to eliminate discrepencies among point clouds from overlapping passes. The latency is a time synchronization delay of the MLS sensors. It is associated with the geolocalisation time of a lidar return point with respect to its physical measurement. Lever arms are distances between the origin frame of one sensor to another. The accuracy of lidar ranging from a MLS is therefore intimately bounded to the rigorous adjustment of this complex metrological set. Currently, with the democratization of the market and the increased accessibility of low cost solutions, the integration of an MLS becomes a subjective recipe but it remains a complex and dicult task. However, aside from well renowned commercial solutions such as Riegl, Leica and Trimble, whose adjustment methods remains specic to theirs products, independent adjustment methods of MLS that allow the user to control their integration parameters are still needed. The goal of this research project is to provide a wide range of users with a generic, easy-to-implement boresight angles adjustment method that does not require the use of top-grade laboratory instruments, while at the same time achieving results as reliable as more labored adjustment methods, representing then a real added value.
Document Type: Mémoire de maîtrise
Issue Date: 2019
Open Access Date: 8 August 2019
Grantor: Université Laval
Collection:Thèses et mémoires

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