 |
| Titel |
Vision-Based Geo-Monitoring - A New Approach for an Automated System |
| VerfasserIn |
A. Wagner, A. Reiterer, P. Wasmeier, D. Rieke-Zapp, T. Wunderlich |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250065513
|
|
|
|
|
|
| Zusammenfassung |
| The necessity for monitoring geo-risk areas such as rock slides is growing due to the
increasing probability of such events caused by environmental change. Life with threat
becomes to a calculable risk by geodetic deformation monitoring. An in-depth monitoring
concept with modern measurement technologies allows the estimation of the hazard potential
and the prediction of life-threatening situations. The movements can be monitored by sensors,
placed in the unstable slope area. In most cases, it is necessary to enter the regions at risk in
order to place the sensors and maintain them. Using long-range monitoring systems (e.g.
terrestrial laser scanners, total stations, ground based synthetic aperture radar) allows
avoiding this risk.
To close the gap between the existing low-resolution, medium-accuracy sensors and
conventional (co-operative target-based) surveying methods, image-assisted total stations
(IATS) are a suggestive solution. IATS offer the user (e.g. metrology expert) an image
capturing system (CCD/CMOS camera) in addition to 3D point measurements. The images of
the telescope’s visual field are projected onto the camera’s chip. With appropriate calibration,
these images are accurately geo-referenced and oriented since the horizontal and vertical
angles of rotation are continuously recorded. The oriented images can directly be used for
direction measurements with no need for object control points or further photogrammetric
orientation processes. IATS are able to provide high density deformation fields with
high accuracy (down to mm range), in all three coordinate directions. Tests have
shown that with suitable image processing measurements a precision of 0.05 pixel ±
0.04-
Ïă is possible (which corresponds to 0.03 mgon ± 0.04-
Ïă). These results have to
be seen under the consideration that such measurements are image-based only.
For measuring in 3D object space the precision of pointing has to be taken into
account.
IATS can be used in two different ways: (1) combining two measurement systems and
measuring object points by spatial intersection, or (2) using one measurement system and
combining image-based techniques with the integrated distance measurement unit. Beside the
system configuration, the detection of features inside the captured images can be
done on the basis of different approaches, e.g. template-, edge-, and/or point-based
methods.
Our system is able to select a suitable algorithm based on different object characteristics,
such as object geometry, texture, behaviour, etc. The long-term objective is the research,
development and installation of a fully-automated measurement system, including a data
analysis and interpretation component.
Acknowledgments: The presented research has been supported by the Alexander von
Humboldt Foundation, and by the European Sciences Foundation (ESF). |
|
|
|
|
|
|