Updating of hydrographic features in topographic base information based on airborne laser scanning data
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School of Engineering |
Master's thesis
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Date
2013
Department
Major/Subject
Kartografia ja geoinformatiikka
Mcode
Maa-123
Degree programme
Language
en
Pages
vi + 85
Series
Abstract
Hydrographic features in topographic base information require regular updates because land surface conditions and product needs change over time. Traditionally similar procedures have been carried out by the photogrammetric techniques, which are considered of poor quality for channel extraction at a basin scale these days. Owing to the fact that correction of datasets is no longer a cost-effective process, re-producing best quality data often seems the safest option. Airborne laser scanning (ALS) has proven a major contributor to the revision of different datasets in recent times, including of hydrographic features. The focus of the thesis was on the watercourses (line) of the National Land Survey of Finland Topographic database (TDB), represented on the application scale 1:10 000. The thesis considers three different spatial data quality measures for estimating the error inserted by the system in ALS based DEMs, including a multiple buffer positional accuracy for linear features, root mean square error and channel sinuosity. These measures will serve as a comparison of different streams on a study in the surroundings of Nuuksio National Park (Espoo, Finland). The results show that the vector flow extraction from ALS-derived DEMs are considerably denser and closer to the observations in the field than those derived from the NLS 1:10 000 TDB watercourse (line). Similarly, the method under study offers significant support for conventional means of capturing highly detailed hydrographic features from all types of topographies for the update of maps.Description
Supervisor
Virrantaus, KirsiThesis advisor
Oksanen, JuhaKeywords
topographic database, digital elevation model, hydrological modelling, geomorphometry, water runoff, channel extraction