Terrestrial lidar data from northern Monterey Bay, California, September 2017

Dates

Publication Date: 2017
Start Date: 2017-09-20
End Date: 2017-09-21

Citation

Stevens, A.W., Logan, J.B., Snyder, A.G., Hoover, D.J., Barnard, P.L., Warrick, J.A., 2017, Beach topography and nearshore bathymetry of northern Monterey Bay, California: U.S. Geological Survey data release, https://doi.org/10.5066/F76H4GCW.

Summary

This part of the data release presents topography data from northern Monterey Bay, California collected in September 2017 using a tripod-mounted Riegl VZ-1000 lidar scanner (USGS Field Activity 2017-678-FA). For each area surveyed, the scanner was placed at several positions which were selected to provide maximum line-of-sight coverage of the area of interest. Scans were typically conducted in panoramic mode, creating a detailed point cloud of all unobstructed surfaces in a 360 degree view of the scanner. At each scan position, co-registered photographic imagery was also collected with a scanner mounted DSLR camera. Scanner registration was performed by placing four or more cylindrical or flat reflective tripod-mounted targets in view [...]

Summary

This part of the data release presents topography data from northern Monterey Bay, California collected in September 2017 using a tripod-mounted Riegl VZ-1000 lidar scanner (USGS Field Activity 2017-678-FA). For each area surveyed, the scanner was placed at several positions which were selected to provide maximum line-of-sight coverage of the area of interest. Scans were typically conducted in panoramic mode, creating a detailed point cloud of all unobstructed surfaces in a 360 degree view of the scanner. At each scan position, co-registered photographic imagery was also collected with a scanner mounted DSLR camera. Scanner registration was performed by placing four or more cylindrical or flat reflective tripod-mounted targets in view of the scanner. The positions of these reflectors were measured using global satellite navigation system (GNSS) receivers, and used in post-processing to register each point cloud into a projected coordinate system.

Initial data processing of the terrestrial lidar data was conducted using Riegl RiscanPro software. Each scan position and point cloud was registered using the GNSS-measured positions of the tripod-mounted reflectors. The quality of the registration was visually compared against adjacent registered point clouds, and concurrently collected topographic GNSS data. In the unlikely case that initial registration appeared to be inaccurate either due to poor GNSS precision, or poor reflector geometry, a point cloud fitting process called “Multi-Station Adjustment (MSA)” was used to adjust the spatial registration to match adjacent point clouds. After registration was completed, the point clouds were colorized using RGB pixel values from the co-registered photographic imagery. The point clouds were hand-edited to remove erroneous data points below the true ground surface caused by reflections on wet sand or water. Additional noise from water, breaking surf, haze, and objects within the point cloud were also removed by hand editing. The point clouds were exported to comma delimited (.csv) format and converted into LAS format and processed using the LAStools software suite. A batch script was used to: 1) clip the LAS files to the areas of interest, 2) perform a range filter to remove all points further than 700 meters away from the scanner, 3) thin the point cloud to an average spacing of 5 centimeters to reduce point density, and 4) perform a classification algorithm to detect ground points and remove objects and vegetation from the point cloud. At this point a final visual check on the remaining points was performed to verify and correct any misclassification of ground surfaces. To produce the final output files all classified ground points were thinned using the lowest elevation point in 10 centimeter cells, and the resulting points were exported to a comma-separated text (.csv) file.

Contacts

Point of Contact :: Joshua B. Logan
Originator :: Joshua B. Logan, Alexander G. Snyder
Metadata Contact :: Joshua B. Logan
Publisher :: U.S. Geological Survey
Distributor :: U.S. Geological Survey - Science Base

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mb17_sept_tls_metadata.xml Original FGDC Metadata	View	19.16 KB	application/fgdc+xml
mb17_sept_tls_capitola.csv “Comma-separated text”		32.97 MB	text/csv
mb17_sept_tls_santacruz.csv “Comma-separated text”		99.18 MB	text/csv

Purpose

Data were obtained to document changes in shoreline position and coastal morphology as they relate to episodic (storms), seasonal, interannual, and longer (for example, El Niño) processes. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify topographic and shallow-water bathymetric features.

Terrestrial lidar data from northern Monterey Bay, California, September 2017

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