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| TUNNELS |
Acquiring tunnel featurers has been limited to traditional methods of surveying to more recently static scanning, but this acquisition still required placing the surveyor in a confined dangerous environment. Recent advances in TMLS now gives the surveyor a third option to collect survey grade data inside tunnels. . Elements that can be captured in highway or rail tunnels: Alignment
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Downloadable Brochures and Spec Sheets
Simulated Tunnel Accuracy Report |
4. StreetMapper Accuracy Trials
4.1. Project Simulated Tunnel
A test was performed to determine the performance of StreetMapper inertial navigation system after driving through periods of sustained GPS outage due to tunnels of various lengths.
Since it is difficult to establish accurate control points within tunnels, it was decided to simulate the effect of tunnnels by driving on a regular road and removing GPS epochs from the differential GPS (dGPS) soultion files for each of four simulated tunnel lengths and comparing the data to control run that utilises all GPS epochs.
The StreetMapper was driven along a 3 km stretch of the A52 in Bingham, UK. Between 6 and 7 GPS satellites were avaiable during the mission, producing and average PDOP of 2.5...
