Geography Reference
In-Depth Information
3.2.2. “GPSVan
TM
” achieved by the “Mapping Center” from the Ohio State University
(Brzezinska et al., 2004)
A similar example of a mobile system for mapping and data collection, which can map
railroads, thoroughfares and transport infrastructures (as for example, roads, circulation
signs and bridges) during its displacement at posted road speeds is represented by
“GPSVan™” system achieved by the Mapping Center from the Ohio State University and
which is also composed of two main components: a positioning module and an imagery
module. This imagery module includes, also, in this case, a stereo metric system with two
video cameras which record the stereo images of the roads during the displacement on the
respective arteries of the lab vehicle. Each video frame is time marked with the GPS signal
and the geodesic coordinates (latitude, longitude and ellipsoidal height, respectively) are
attributed to each image.
From the above presented aspects, it results that both the GPSVision
TM
and GPSVan™
equipments represent, in their essence, a fix-based stereovision system with known position
and attitude, provided by the GPS/INS component and, respectively, by the GPS/DRS
component. This fixed base is represented by the distance, on the hood width of the lab
vehicle, between the optical distances of the two video cameras, mounting distance which in
the case of both GPSVision
TM
and GPSVan™ equipments is approximately of 1.2 meters. As
a consequence of the fixed base reduced value, the difference between the angles of sighting
directions of the two video cameras is under the minimum value it can be measured by the
optical system when the sighted targets are situated at a distance, greater then
approximately 40 meters, in respect to lab vehicle. This limitation of the observing distance,
at a quite reduced value, represents in its essence the main disadvantage of the stereo metric
systems, which are based on the use of a pair of video cameras, mounted on the same lab
vehicle.
4. Originality of the proposed Mobile Slide Monitor (MSM)
The static regime systems, previously described, achieve the stability monitoring of the
constructions by using precision optical systems or GPS equipment with differential regime
functioning, but to which the follower receiver is attached in a fixed montage on the
surveyed construction. As opposed to these systems the monitoring system presented here
has the advantage that it permits measurements to be rapidly performed, at preset time
interval, with a reduced cost on a multitude of objectives and with a minimum delay
between the moment of some defection occurence and the moment of its identification and
alarming.
Taking account of the above-mentioned characteristics of the bi-cameral stereo-metric
systems, the INOE 2000 Institute from Bucharest elaborated the Invention Patent RO 126294
A2/2009 whose main objective was to increase up to U200 - 300 metersU, the distance up to
which the sighted targets from the terrain can be positioned.
Conceptually this Mobile Slide Monitor - MSM involves:
