View
2
Download
0
Category
Preview:
Citation preview
Laser Scanning Survey in the Pál‐völgy Cave, Budapest
M. Gede 1, C. Petters
2, G. Nagy 3, A. Nagy 4,J. Mészáros
1, B. Kovács
1, Cs. Egri
5
1Department of Cartography and Geoinformatics, Eötvös Loránd University, Hungary2Institue for Cartography, TU Dresden / FARO Europe, Germany
3Faculty of Geoinformatics University of West Hungary, Székesfehérvár, Hungary 4GeoLink3D Ltd., Budapest, Hungary
5Ministry of Rural Development, Department of National Parks and Protected Landscapes, Budapest, Hungary
Outline
About the cave
Problems of cave surveying
Equipment
The survey
Results
Conclusions
Further plans
About the caveBudapest – the capital of caves (~100 caves under the town)
The Pál‐völgy Cave ‐
with recently found connections to neigbouring
caves – is part fo the longest cave system in Hungary (28 km)
Only 600m is open to the public (with pavement, handrails etc.)
Why this cave?
‐
Easily accessible‐
The survey of the public parts can be finished
in one day
Problems of cave surveying
‐
Underground work – no GPS, no GSM network , darkness, communication problems
‐
Humidity – not perfect conditions for measuring instruments‐
Hard terrain (in undeveloped caves)
‐
Visitors (developed caves, open to the public)
‐
Traditional survey (gyrocompass, tape measure) –
uncertain, big errors
‐
Survey with a total station – not suitable for complex‐shaped chambers
‐
Terrestrial laser scanning –
good, fast, but the equipment is expensive and vulnerable; processing of resulting point clouds
requires high‐performace computers
Equipment
Faro Focus3D
(GeoLink3D Ltd.) Leica ScanStation C10 (Univ. of West Hungary)
Our university does not own a TLS;No financial support for the project
Spectra Epoch RTK GPS for measuring outer control points
Help from a partner university and a private company of former students
ResultsWebsite with scanner panoramas and overview map
Flash panorama viewer
OpenLayers overview map
ResultsVector map of pavements, stairs, handrails based on the point cloud
Serious accuracy issues of the old map
Conclusions
Advantages of Faro Focus3D:‐Faster scanning‐Smaller weight and size‐Automatic recognition of control spheres
Advantages of Leica ScanStation C10:‐Longer range‐Fewer control points (automatically finds vertical axis)
When surveying in caves without large chambers the Faro scanner is much more suitable.
Further plans
‐
The compilation of a new, much more accurate map of the cave (in progress)
‐
Creating simplified 3D surface model of the cave‐
Examining
the use of control spheres instead of discs for the Leica
system (to speed up the surveying)‐
Scanning additional parts of the Pál‐völgy
Cave (where the
circumstances make it possible, the scanning scenes have to be approachable by considerably wide corridors to ensure that the instruments can be carried in safely)
‐
Scanning other Hungarian caves. The most promising plan is to survey in the Baradla
Cave in North‐Eastern Hungary, where huge halls follow
each other for several kilometers. The wide corridors and the large sizes make this cave an ideal subject for a TLS survey.
Recommended