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- Title
Applicability of mobile laser scanning to road surveying.
- Authors
Gröhn, Simo
- Abstract
The objective of this M.Sc. Thesis was to study the suitability of mobile laser scanning for road surveying. Literature research was used to establish test methods to be used to determine the suitability of mobile laser scanning for road surveying. Data used in the study was measured in Valtatie 6 -road with Trimble mx 8 -mobile laser scanner. Suitability for road surveying was evaluated in the following categories: accuracy, efficiency, measurement of the condition of the road surface, measurement of road asset condition and modelling of road geometry and road layout criteria. Absolute accuracy and precision of mobile laser scanning was examined. Best absolute accuracy was achieved with ground control points spaced 100 meters apart. Largest error was 2.5 cm in XY plane and 1.1 cm in height. Precision was defined as standard deviation of 3 mm. Mobile laser scanning efficiency was studied by measuring the density of measurements on the road surface. Afterwards a comparison between different measurement methods was made by comparing the differences of measured surfaces. Point density of mobile laser scanning was measured at over 4,000 points per square meter on the road surface. Because of the highest point density, mobile laser scanner was able to model best the road surface. Suitability for measurement of road surface condition was in longitudinal road profile, cross-profile and pavement damage mapping. Problem in longitudinal road profile measurements was low point density in the direction of the road. Evaluation of suitability for measuring cross-section of the road was carried out comparing mobile laser scanner measurements to profile laser measurements. Rut and water rut of the toad surface was inspected. Mobile laser scanner gave same results as profile laser measurements. Road pavement damage mapping was implemented successfully by manually observing cracks from orthophotos and point cloud. Road asset condition was addressed by examining road markings, traffic signs, railings and bus stop shelters. Condition of road markings was examined from orthophoto and intensity feature of measured points. Condition of structures of other objects was studied from point cloud. Texture was analysed from photos taken by the mobile scanner. Suitability for modelling of road geometry and road layout criteria was inspected by computing descriptors used in road planning. These descriptors include for example longitudinal road section, cross-section, sight distances and component fitting, modelling of road geometry and road layout criteria with mobile laser scanner was found to work generally very well. Mobile laser scanner performed excellently in road surveying overall. With help of image and point cloud data mobile laser scanning brings effective and fully three-dimensional modeling to road surveying. Thus, it could be possible to develop new methods for road construction and maintenance. With mobile laser scanning it is possible to model the environment much more extensively than with any other road surveying method at the moment.
- Subjects
ROAD surveying; ROAD construction; OPTICAL scanners; COMPUTER software
- Publication
Photogrammetric Journal of Finland, 2016, Vol 25, Issue 1, p26
- ISSN
0554-1069
- Publication type
Abstract