## 2 Materials and Methods  
### Experiment Location and MMS POS/LV Description and Configuration  
The kinematic tests were carried out in Basovizza, a district on the outskirts of the Municipality of Trieste, Italy. The researchers drove the MMS vehicle at constant speed along the internal paved roads of the Sincrotrone Elettra Research Center Park. This particular site was chosen in order to maximize satellite visibility and signal-to-noise ratio, as it is located on the Karst plateau, at an average altitude of 375 m above mean sea level, with a clear view on all sides. The only relevant visibility obstacle is Mount Cocusso (674 m), located at 3.5 km in the NE direction (Figure 1).  
For the absolute positioning, the Mobile Mapping System uses the Applanix Corporation POS/LV System, a fully integrated, position and orientation system, with GNSS positioning integrated by inertial technology to generate stable, reliable, and repeatable positioning solutions for land-based vehicle applications (Figure 2). Designed to operate under the most difficult GNSS conditions in urban and suburban environments, it enables accurate positioning for road geometry, pavement inspection, GIS database and asset management, road surveying, and vehicle dynamics [42]. The integratedGNSS/INS (Global Navigation Satellite System/Inertial System) is able to provide, instant by instant, the position and attitude of the vehicle. Besides the two geodetic GNSS receivers and the Inertial System, there is also an odometer mounted on the rear-left wheel of the vehicle, measuring the distance traveled. The inertial system integrates GPS in case of no satellite signal due to obstacles such as bridges, trees, buildings, to give positioning accuracies comparable to the ones obtainable through differential techniques. A Kalman filter, which allows to gain the best solution at any time, performs the integration of each sensor data. GNSS data has a 1 Hz acquisition rate, while the odometer and the inertial system send data to the System CPU at a rate of 200 Hz.  
In the present research, all positioning data were referred to the Leica GS14 [43] receiver antenna phase center. This was done to directly compare, epoch by epoch, the positions computed using GS14 data with the MMS reference trajectory.  
The PCS (POS Computer System) is the central element of the Applanix system: it acquires and processes data coming from the different sensors, giving the positioning and attitude parameters of the vehicle in real-time, and stores them for subsequent post-processing. The integrated inertial system is a Litton LN-200 fiber optic gyro IMU with three accelerometers and three fiber optic laser gyros. A DMI (Distance Measuring Indicator) is mounted on the rear-left wheel of the vehicle and contains an optical sensor generating 1024 pulses per revolution; its function is to estimate the run distance and, above all, to determine when the vehicle has come to a halt (ZUPD--Zero velocity UPDate). Two geodetic GPS receivers send the data to the PCS for positioning and direction determination, the latter utilizing the GAMS (GPS Azimuth Measurement Subsystem) software module.  
Figure 1: Surveyed Area. In yellow, the reference trajectory produced by the Mobile Mapping System Position and Orientation System for Land Vehicles (MMS POS/LV—Mobile Mapping System, Position and Orientation Systems for Land Vehicles) system. Reference system: RDN ETS89-ETRF2000.  
Figure 2: The MMS of the GeoSNAv Lab, University of Trieste, and the Applanix Corporation POS/LV® system components mounted on board the vehicle. MMS data were used to create the reference trajectory.