4th Workshop of the Japanese-Croatian Project on ‘Risk Identification and Land-Use Planning for Disaster Mitigation of Landslides and Floods in Croatia’ Split (Croatia), 12-14 December 2013
APPLICATION OF ‘STRUCTURE-FROM-MOTION’ PHOTOGRAMMETRY FOR EROSION PROCESSES MONITORING, MOŠĆENIČKA DRAGA EXAMPLE Igor Ružić1, Ivan Marović1, Martina Vivoda1, Sanja Dugonjić Jovančević1, Duje Kalajžić2, Čedomir Benac1, Nevenka Ožanić1 1University
of Rijeka, Faculty of Civil Engineering 2University of Rijeka, IT Services
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Digital Elevation Model
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Research idea
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Tools and resources
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Examples
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Conclusions
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OUTLINE
Structure-from-Motion photogrammetry and 3d point cloud
‘Structure-from-Motion’ (SfM) operates similarly as stereoscopic photogrammetry, 3-D structure can be resolved from a series of overlapping, offset images. SfM photogrammetry: The scene geometry, camera positions and orientation are solved automatically Approach is most suited to sets of images with a high degree of overlap that capture full three dimensional structure of the scene viewed from a wide array of positions, or as the name suggests, images derived from a moving sensor
Developed in the 1990s, this technique has its origins in the computer vision community Available various free SfM Softwares
SFM PHOTOGRAMMETRY
What is Structure-from-Motion photogrammetry?
A point cloud is a set of data points in some coordinate system. In a three-dimensional coordinate system, these points are usually defined by X, Y, and Z coordinates, and often are intended to represent the external surface of an object. In geographic information system, point clouds are one of the sources to make digital elevation model of the terrain. The point clouds are also employed in order to generate 3D model of urban environment, e.g. 3D point cloud can be generated using: 3d scanners, laser scanning, terrestrial radar, photogrammetry, SfM photogrammetry etc.
3D POINT CLOUD
3D point cloud
DEM HISTORY
What is digital terrain model?
Robers (1957) first proposed the use of the digital computer with photogrammetry as a new tool for acquiring data for planning and design in highway engineering
DTM Miller & LaFlamme (1958) described the development in detail and introduced the concept of the digital terrain model
“The digital terrain model (DTM) is simply a statistical representation of the continuous surface of the ground by a large number of selected points with known X, Y , Z coordinates in an arbitrary coordinate field.” – definition given by Miller & LaFlamme in 1958 TERMINOLOGY Digital Elevation Model (DEM) – generic term for altitude grid Digital Terrain Model (DTM) – ground elevation model Digital Surface Model (DSM) – ground + cover elevation model Digital Height Model (DHM) – cover elevation model
DSM
DHM
How to produce DEM? • Existing Contour Map • Aerial Photograph • Satellite: • Optical Remote Sensing • SAR – Synthetic Aperture Radar • Laser Scanner • SfM Photogrammetry
DEM DEVELOPMENT
Digital representation of terrain
*James, M. R., & Robson, S., Straightforward reconstruction of 3D surfaces and topography with a camera: Accuracy and geoscience application, Journal of Geophysical Research, 117, 2012.
RESEARCH IDEA
3D Scanner vs SfM; TLS vs SfM– James*
RESEARCH IDEA
3D Scanner vs SfM; TLS vs SfM– James*
*Westoby, M. J., Brasington, J., Glasser, N. F., Hambrey, M. J., & Reynolds, J. M., “Structure-from-Motion” photogrammetry: A low-cost, effective tool for geoscience applications, Geomorphology, 179:, 300–314, 2012.
RESEARCH IDEA
Applications of SfM photogrammetry in geoscience – Westoby, 2012*
*Westoby, M. J., Brasington, J., Glasser, N. F., Hambrey, M. J., & Reynolds, J. M., “Structure-from-Motion” photogrammetry: A low-cost, effective tool for geoscience applications, Geomorphology, 179:, 300–314, 2012.
RESEARCH IDEA
Applications of SfM photogrammetry in geoscience – Westoby, 2012*
Photo equipment
FIELD WORK
3D SCANNING
OFFICE WORK
3D MODELLING
RTK-GPS 123D Catch/ReCap (Autodesk) CloudCompare Matlab
DIGITAL ELEVATION MODEL (DEM)
TOOLS AND RESOURCES
Available tools and resources
One of research locations in Croatian-Japanese project „Risk identification and land-use planning for disaster mitigation of landslides and floods in Croatia”
MOŠĆENIČKA DRAGA EXAMPLE
Mošćenička Draga – example of monitoring area
Investigation aims: • Monitoring of steep to vertical slopes formed in talus breccias • Application of SfM photogrammetry • Possible landslide • Possible landslide lake formation and debris flow • Implementation of Mošćenička Draga Early warning System
LOCATION OF MONITORING AREA
Mošćenička Draga – example of monitoring area
Investigation aims: • Monitoring of steep to vertical slopes formed in talus breccias • Application of SfM photogrammetry • Possible landslide • Possible landslide lake formation and debris flow • Implementation of Mošćenička Draga Early warning System
LOCATION OF MONITORING AREA
Mošćenička Draga – example of monitoring area
2012-11-05
2013-11-28
MONITORING PROCESS
Mošćenička Draga – two SfM 3D Point Clouds were compared
SEDIMENT ACCUMULATION
3d Point Cloud and x profiles (-15:5:+15)
profile 5
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X profile 5 Sediment accumulation between y axis 11m and 21m
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X profile 15 Sediment erosion between y axis 11m and 21m
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[m] 11 10
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SEDIMENT EROSION
3d Point Cloud and x profiles (-15:5:+15)
SEDIMENT ACCUMULATION
3d Point Cloud and x profiles (-15:5:+15) Y profile 20 Sediment accumulation between x axis 6m and 14m
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COMPARISON
3d Point Cloud and x profiles (-15:5:+15) Y profile 20 Good profile matching
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EXAMPLES
Havišće – example of field and office work
EXAMPLES
Havišće – example of field and office work
EXAMPLES
Point cloud and profiles
EXAMPLES
Visualization and results
EXAMPLES
Visualization and results
Presented 3D point cloud derived from an image set has adequate quality for valuable use in visualizing and quantifying slope morphological changes • cloud density about 2000 points per square meter • Standard ReCap 3D model mesh size is used (in order to get higher density it is possible to use even higher mesh size) • Ground Control Points – definition
This technique is convenient for frequent acquisition of high-resolution DEM at a fraction of the time and cost of alternative approaches One of the application of SfM photogrammetry method is monitoring of landslide movements Possible as well in real-time landslide monitoring processes
CONCLUSIONS
Final remarks
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