ON THE ACCURAY AND PERFORMANCE OF THE GEOMOBIL SYSTEM 
R. Alamus, A.Baron, E.Bosch, J.Casacuberta, J.Miranda, M.Pla, S.Sanchez, A.Serra, J.Talaya 
Institut Cartografic de Catalunya (ICC), Parc de Montjuic, E-08038 Barcelona 
(ralamus, abaron, ebosch, jcasacuberta, miranda, mpla, santis, aserra, talaya)@icc.es 
Commission II, WG V/2 
KEY WORDS: Mobile Mapping System, CCD, Laser scanning, Calibration, Accuracy 
ABSTRACT: 
The GEOMOBIL is a Land Based Mobile Mapping System (LBMMS) developed by the ICC. It is a modular system that allows the 
direct orientation of any sensor mounted on a roof platform. The GEOMOBIL system is composed of the following subsystems: 
orientation subsystem, image subsystem, laser ranging subsystem, synchronization subsystem, power and environmental control 
subsystem and data extraction software subsystem. 
After a brief description of the GEOMOBIL system, the paper focuses on the calibration and performance of the GEOMOBIL image 
subsystem. It describes the calibration of the CCD (Coupled-Charged Device), cameras used (camera calibration) and the calibration 
of the boresight parameters (eccentricity and misalignment of the image sensors with reference to the GPS/IMU reference frame). 
The accuracy and stability of the boresight camera calibration are also discussed. In order to evaluate the accuracy and performance 
of the system, several missions have been carried out under different configurations and environments. An operator has measured 
elements in the images by using data extraction software developed by the ICC as part of the GEOMOBIL system. The results of the 
campaigns in terms of the accuracy and performance of the GEOMOBIL are discussed and conclusions are drawn. 
Finally, the paper gives a brief description of the future developments related to the integration of new sensors into the GEOMOBIL 
platform. In particular, a terrestrial laser scanner has recently been installed and the first results are presented. 
1. INTRODUCTION 
The GEOMOBIL is the multi-sensor land based platform 
developed at the ICC. It can acquire data from different sensors. 
Up to now two CCD monochrome digital cameras and a 
terrestrial laser system, which are operated simultaneously with 
a direct orientation subsystem and are accurately synchronized 
to GPS time, have been integrated into the system. 
In addition to being a geographic data acquisition system, the 
GEOMOBIL is a system for acquiring and georeferencing 
sensors and a software package for extracting information from 
acquired data. 
Based on a platform able to integrate any sensor and a direct 
reference subsystem, the GEOMOBIL system is meant to be a 
tool capable of acquiring geographic data with cartographic 
accuracy requirements in a production environment. 
2. GEOMOBIL SYSTEM 
With the objective of developing an LB-MMS flexible enough 
to integrate several sensors for acquiring data of cartographic 
interest, the ICC started the GEOMOBIL project, which, at this 
first stage, integrates the positioning and orientation 
subsystems, algorithms and sensors required to determine 
coordinates of observed elements applying photogrammetric 
techniques. In order to transfer the different reference frames, 
the system is equipped with a rigid structure where the 
image/laser sensors, orientation and positioning subsystems are 
physically installed. To begin with, two digital cameras that 
form stereoscopic models in the zone of interest are employed. 
The zone of interest is defined to be at a 10m distance from the 
vehicle along track and a 10m distance wide across track in 
order to acquire all the elements in the photographs, such as 
horizontal and vertical road signs. The integration platform is 
mounted on a vehicle that equips other auxiliary subsystems for 
the continuous operation of the system, like air conditioning, 
electrical power and other subsystems. Operator security and 
attenuation of the disturbing vibrations present in mobile 
environments are also included. 
  
Figure 1: GEOMOBIL System. 
The GEOMOBIL system has been divided into the following 
subsystems: 
e Orientation: handles the absolute temporal and 
geometric reference frames. 
e Integration Platform: is a rigid physical base for 
the transference of the geometric reference frame 
of all the installed sensors. 
eo Image Sensor: handles scene configuration, 
sensor geometry and parameters. 
    
  
   
  
   
  
  
  
   
   
   
   
    
  
   
   
  
  
  
  
  
  
  
   
  
  
   
   
   
   
  
   
  
  
  
   
  
  
  
  
  
   
  
  
  
    
   
  
  
  
  
  
  
   
        
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