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MMT 2015 (9TH INTERNATIONAL SYMPOSIUM ON MOBILE MAPPING TECHNOLOGY)
09/12/2015 @ 9:00 AM - 11/12/2015 @ 5:00 PM
Carlos Gonzales from our Australian Office will be attending MMT in Sydney this December. He will also be presenting 'Quantifying coastal slope instability through integrated
time-series airborne laser scanning and photography'.
Measurements of unstable slopes in coastal areas are important to determine the associated hazards and potential impacts upon local infrastructure. Due to the often inaccessible nature of
coastal terrain, survey data is typically captured using periodic airborne laser scanning and photographic surveys. Whilst both techniques offer a number of key advantages, there also limitations.
Airborne laser scanning provides 3-D data suitable for measuring surface elevation changes, but the spatial resolution of measurements can limit the ability to track small-scale surface movements. In contrast to this, airborne photographic surveys are suitable for identifying the displacement of small-scale surface features, but periodic 3-D data derived from photographs are sensitive to changes in vegetation and are thus often not fully representative of the absolute terrain surface elevation.
Here, we explore the capabilities of integrated time-series online-waveform airborne laser scanning and photography as an approach to measure slope movements, using a case study
from a section of the North-Yorkshire coast in the UK. Laser and photographic data were captured at the same time during two airborne surveys performed approximately nine months apart.
Changes in surface elevation over time were derived using automated lidar processing techniques. To determine displacement velocities, surface features were tracked in consecutive
images in the time-seriessequence using computer-vision techniques. After feature tracks were calculated, the 2-D pixel-measurements were converted into 3-D feature trajectories by reprojecting the image features onto the laser derived topography.
Through combining surface elevation changes derived from laser data and displacement velocities calculated from images, we were able to quantify both the volume of displaced
material, and the rate and direction over which the displacement occurred. The results demonstrate that integration of laser scanning and automated feature tracking using photographs can be used to provide comprehensive measurements of slope instability.
To arrange a meeting or to find out more, email us at email@example.com