Three-Dimensional Road Profiling Using Stereography.

Road profiles are usually obtained by measuring a line of points in the lateral direction of the road while moving longitudinally using some kind of position sensor that is mounted to some kind of moveable platform, i.e. a vehicle. These line scans are then joined together to create a 3 dimensional road profile.  The movement of the position sensor causes a change in the relative position and orientation of these line scans. This change in position and orientation needs to be accurately determined in order to combine the line scans to obtain an accurate representation of the measured profile. The position and orientation of the sensor is normally measured using an  expensive Inertial Measurement Unit (IMU) with high sensitivity, low noise and low drift.

This paper proposes a road profiling technique which utilises stereography, based on two inexpensive digital cameras, to obtain three-dimensional measurements of the road. The advantage of this technique is that each measurement results in a surface containing lateral and longitudinal position as well as height, rather than a traditional line scan as in most systems.  Corresponding camera images are taken such that they have an area which overlap. The relative position and orientation between the individual surfaces can be obtained using either 2 dimensional or 3 dimensional features in the corresponding surfaces. This creates a system which negates the use of an expensive IMU system to determine orientation and position of each measurement. The proposed system is especially well-suited to profiling rough off-terrain for use in ride dynamics and terramechanics studies.