RECENT ADVANCES APPLYING TERRESTRIAL LIDAR TO EARTHQUAKE LANDSLIDE RESEARCH
Robert Kayen(USGS, Menlo Park, CA & UCLA, USA) Scott Ashford, (Oregon State University, USA) Jon Stewart (UCLA, USA) Brian Collins (USGS, Menlo Park, CA, USA) International Conference in Commemoration of 10th Anniversary of the Chi-Chi Earthquake, 2009. Jungli, Taiwan, 21 September 2009 RECENT ADVANCES APPLYING TERRESTRIAL LIDAR TO EARTHQUAKE LANDSLIDE RESEARCH
Terrestrial LIDAR Technology (Light Detection and Ranging) Methods, Metrics, & Overcoming limitations Landslide analysis for change detection: (Daly City, California, USA) Blind Comparison of Air- and Terrestrial-LIDAR Accuracy: (Los Angeles Reservoir, California, USA) High resolution change detection using LIDAR: (PARI Liquefaction site, Ishikari, Hokkaido, Japan) LIDAR LIDAR (Light Detection and Ranging)
Laser pulse backscatter off landslide Scanning mirror directs laser beam Distance = (c x Tflight)/2 Rapid and SAFE Captures complexity of surfaces Geometric analysis of landslide Change-detection Permanent virtual archive Niigata Chuetsu, 2004 Laser Pulse RGB Color Since the laser pulse travels at the speed of light, accurate timing is necessary to obtain fine vertical resolution.For example, a one nanosecond timing resolution allows a range measurement accuracy of about 30cm.Timing technology allows for measurements of < 5cm Scanning mirror directs laser pulse back and forth across track.In shoals the track is an arc. Typical Terrestrial LIDAR Setup
RTK-DGPS Base RTK-DGPS Rover Photogrammetric Camera Laser Benchmark USGS Terrestrial LIDAR
Laser : Reigl z m z420i -1000m range Scan-to-scan registration Reflector Registration Bare Ground Error Budget: Laser rangefinder error = cm GPS error ~1 cm+ Registration Error = 2-5 cm EstimatedRMSE cm vertical Heavily Vegetated Ground: Significant positive residuals associated with inability to extract true bare earth model Processing Procedures
B: Register. A: Scan Niigata Ken, Japan D: Quantify Deformations C: Filter & Fuse Surface 5.69m multiple scans eliminate shadow zones
Embankment Failure, Rt 252 Niigata, Japan multiple scans eliminate shadow zones (2 false-colored scans in white and red) s Overcoming Shadow-Casting Obstacles
High-altitude (20 m)Terrestrial LIDAR Downward view of terrain/vegetation Improved grazing angle Flat terrain max range = H / tan 3-5 USGS Space Needle GEOREFERENCED REFLECTOR REGISTRATION:
RTK-DGPS registered best fit to common reflectors. BENCHMARK BASE & Reflector Laser 1 - position Laser 2 - position Nantou County, Taiwan Composite Lidar Data: Merged scans from all orientations to eliminate shadows 100m Lake Sinizzo, Abruzzo, Italy April, 2009 10 Scans Landslide analysis for change detection: (Daly City, California, USA) 2007 Landslide reactivation of 2003 slide site in Merced Frm
2007 Landslide reactivation of 2003 slide site in Merced Frm. Weakly cemented sandstone with some slope failure in 1989 earthquake. Pre-2007 Event Data, (2003) Post-Event Data, Jan. 2007 Plan View
Oblique View Post-Event Data, Jan. 2007 Lidar Surfaces for change assessment using cross sections GIS-map of lidar surface changes in 2007 (120,000m3, 1/3 of 2003 event)
Oblique photo and change map Relative multi-epoch vertical accuracy (pre- and post-event imagery).
Blind Comparison of Terrestrial & Airborne LIDAR to Evaluate Potential Landslide Displacements at Los Angeles Dept. Water & Power Facilities Relative multi-epoch vertical accuracy (pre- and post-event imagery). Coincident measurements with Total Station. Assessment of bias and dispersion. (Collaboration between MCEER, LADWP, UCLA, USGS) LADWP Study Site: Los Angeles Reservoir, Van Norman Complex San Fernando Valley, CA Trench Study at Los Angeles Reservoir is intended to evaluate bias and dispersion without influence of vegetation Pre-Trench Post-Trench Post-Trench 120 cm Benching at 10, 20, 40, 60, 80, cm Laser Rangefinder: Optech ALTM 3100 1064nm w/ integrated IMU & GPS.
Airborne LIDAR Laser Rangefinder: Optech ALTM 3100 1064nm w/ integrated IMU & GPS. Flight 1: Fixed wing at 900m (Airborne1, El Segundo, California) Flight 2: Helicopter at 210m (Terrapoint, The Woodlands, Texas) Laser rangefinder error = 2-3 cm GPS error = 5-10 cm IMU error = ~9 m Vendors quoted RMSE 10-18 cm vertical (95% CI) m horizontal (1s) Trench Study at Los Angeles Reservoir: Terrestrial vs. Airborne Data
Terrestrial Pre-Trench Terrestrial Post-Trench 900m Airborne1 210m Terrapoint Airborne Pre-Trench Airborne-Trench RMS Elevation Error Zlidar,i ZTS,i Bias - Residual Mean Dispersion - Residual Std. Dev. For a large sample group (Plane) (Helicopter) RMSE=21.8 cm RMSE=33.8 cm RMSE=6.8 cm RMSE=4.3 cm Los Angeles Reservoir Trench
Normalized residuals Correlation Coefficient (uncorrelated) (weakly correlated) Elevation change residuals measures bias and dispersion in estimating topographic change
R,i = LIDAR,i - TS,i= (Ztl,i - Zt2,i )LIDAR - (Ztl,i - Zt2,i )TS R,i = Rtl,i - Rt2,i RMSE = 8.5 cm RMSE = 22.6cm Blind Comparison of Airborme and Terrestrial LIDAR
Terrestrial LIDAR had almost no bias with pre- and post-trench Airborne LIDAR had negative bias in both pre- and post-trench = cm, and = cm (errors exceeded both vendors specifications) Terrestrial data had 1/4-1/10 mean error and 1/1.4-1/5 dispersion of airborne data. Multi-epoch elevation change terrestrial residuals were 1/3 of airborne residuals. 2009 Journal of Surveying Engineering, ASCE PARI Blast-Liquefaction Experiment: Ultra-fine scale/high precision change detection using Terrestrial LIDAR PARI Experiment Tripod Scans RTK-DGPS Reflector Registration Elevated Scans PARI Ishikari, Hokkaido Test site, Japan, 2008
No Data/Shadow Elimination by Merging Data of Different Orientations PARI Ishikari, Hokkaido Test site, Japan, 2008 60m 4 Scans PARI Experiment: Change maps of Improved and Unimproved Ground on Tarmac area(5 cm contours)
BLAST DAY 2 DAYS AFTER BLAST 100 m Vibro-Compaction/replacement Chem. Grout 4 DAYS AFTER BLAST 5 Months AFTER BLAST RECENT ADVANCES APPLYING TERRESTRIAL LIDAR TO EARTHQUAKE LANDSLIDE RESEARCH
Terrestrial LIDAR Technology (Light Detection and Ranging) Methods, Metrics, & Overcoming limitations Landslide analysis for change detection: (Daly City, California, USA) Blind Comparison of Air- and Terrestrial-LIDAR Accuracy: (Los Angeles Reservoir, California, USA) High resolution change detection using LIDAR: (PARI Liquefaction site, Ishikari, Hokkaido, Japan) RECENT ADVANCES APPLYING TERRESTRIAL LIDAR TO EARTHQUAKE LANDSLIDE RESEARCH
Robert Kayen(USGS, Menlo Park, CA & UCLA, USA) Scott Ashford, (Oregon State University, USA) Jon Stewart (UCLA, USA) Brian Collins (USGS, Menlo Park, CA, USA) International Conference in Commemoration of 10th Anniversary of the Chi-Chi Earthquake, 2009. Jungli, Taiwan, 21 September 2009 34 Google Earth Visualization of Lidar Analysis Airborne LIDAR Error Budget
Laser rangefinder error = 2-3 cm GPS error (single point moving measure) = 5-10 cm IMU error = ,000 ft Usually flown around 2, ,000 ft Yields error of 5-10 cm LA Res. Flights were at 2000 (pre) and 700 (post) (i.e., as low as 2-5 cm error) Most vendors quote 15-18 cm vertical accuracy 0.5-1 m horizontal (depends on height)