Investigating the accuracy of terrestrial laser scanning within a rail environment

Agoritsas, Stavroula (2015) Investigating the accuracy of terrestrial laser scanning within a rail environment. [USQ Project]

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Abstract

Today's technology is so advanced and has reached a point where current regulations need to be reviewed and new technologies need to be incorporated in legislation. For this to take place in the Terrestrial Laser Scanning (TLS) field we need to provide evidence of proven and verified instrument accuracy. The proven working accuracy other than a specification in a product brochure needs to be documented for TLS's to be adopted in Railway industry that requires accurate data.

The aims of this investigation is to document working accuracies for TLS and determine if the instrument conform with Sydney Trains specification by calibrating a scanner.
The existing Track Control Marks (TCM's) represented by very small Survey Steel Pins (SSP's) installed on the face of steel masts in the rail corridor will also be tested to see if they can be scanned accurately . The scan time to capture a rail track scene will also be compared with survey points measured using current Survey Total Station (STS) methods.

Various custom targets using colour tones and material found in the rail corridor have been constructed and tested for scanning useability. An indoor self calibration room has
been established which included the setup of a ground control traverse. A target network has been designed and seventy targets have been installed and signalised. The
Leica TS15 and TS30 STS, have been used to signalise the seventy targets. The calibration targets are a mix of Faro and Leica black and white checker pattern scanner
specific targets. The targets closest to the floor have had an SSP fitted in the centre of the checker pattern target for testing. The indirect method of TLS self calibration
method was used by the Leica P20 ScanStation and the Faro Focus 3D X330 scanners, to scan all the targets form three scan positions. The distances between all the installed
target have been measured with a tape for independent checks on the final 3D positional coordinates of the targets. The two scanners were setup in the rail corridor and scanned a section of rail track. This section of track was also measured by a STS using current Sydney Trains conventional methods. Existing SSP's fitted with scanner targets were scanned and used for the registration of these two point clouds.

It was found when the STS data compared to the Scanners data, the 3D positional coordinates were within +-2 millimetres. This result verifies that the two TLS's are as
accurate as a STS therefore conform with Sydney Trains specifications and can be used in the rail corridor for survey measurements. The SSP testing was successful. They can be scanned and used in the registration process of a point cloud. The mix use of scanner targets with different manufacturer scanner was also successful. When the measured
data from a section of rail tract was scanned and surveyed conventionally, the data was compared and the data once overlayed were identical. This test also documented the
significant difference in time for completing a survey in the rail corridor using a scanner and STS. The documented ability to measure fast and with verified accuracy using a
TLS from a safe place within the rail corridor without encroaching into the danger zone from a safety perspective this is a significant development.


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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Spatial Science (Honours) (Surveying) Project.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Supervisors: Liu, Xiaoye
Date Deposited: 27 May 2016 06:31
Last Modified: 27 May 2016 23:59
Uncontrolled Keywords: terrestrial laser scanning; track control marks; survey steel pins
Fields of Research : 09 Engineering > 0909 Geomatic Engineering > 090906 Surveying (incl. Hydrographic Surveying)
URI: http://eprints.usq.edu.au/id/eprint/29150

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