October 2006 Scripps Institute of Oceanography (SIO) Lidar of Southern California Coastline: Long Beach to US/Mexico Border

There was no metadata record provided along with this data set. Much of the information in this record, has been gleaned from

the metadata record for a data set from this same project, for data collected in March of 2006. The minimal amount of known information that

is specific to this data set has been included in this record where possible.

This lidar point data set was collected during low tide conditions along an approximately 500-700 meter wide strip of the Southern California

coastline within an area extending south from Long Beach to the US/Mexico border. Data were collected in Los Angeles, Orange and San Diego

counties in October 2006. Data set features include water, beach, cliffs, and top of cliffs. The all points data set contains

the complete point cloud of first and last return elevation and laser intensity measurements recorded during the fall 2006 airborne lidar

survey conducted semi-annually by the University of Texas at Austin for the Southern California Beach Processes Study. Data represented is

all points including terrain, vegetation, and structures. This data also contains returns from the water surface. No processing has been

done to remove returns from terrain, vegetation, structures, or water surfaces.

The data set was generated by the processing of laser range, scan angle, and aircraft attitude data collected using an Optech Inc.

Airborne Laser Terrain Mapper (ALTM) 1225 in combination with geodetic quality Global Positioning System (GPS) airborne and ground-based

receivers. The system was installed in a twin engine Partenavia P-68 (tail number N3832K) owned and operated by Aspen Helicopter, Inc.

The lidar data set described by this document was collected in October of 2006. The 99d118 instrument settings for these flights were:

laser pulse rate: 25 kHz

scanner rate: 26 Hz, scan angle: +/- 20 deg

beam divergence: narrow

altitude: 300-600m AGL

ground speed: 95-120kts

Original contact information:

Contact Name: Julie Thomas/Randy Bucciarelli

Contact Org: SCBPS/CDIP, Scripps Institution of Oceanography

Title: Project Managers

Phone: 858-534-3032

The data described in this document will be compared with previous and forthcoming data sets to determine rates of shoreline change along

the Southern California coastline. The SCBPS program is designed to improve the understanding of beach sand transport by waves and currents,

thus improving local and regional coastal management.

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There was no metadata record provided along with this data set. Much of the information in this record, has been gleaned from

the metadata record for a data set from this same project, for data collected in March of 2006. The minimal known information that

is specific to this data set has been included in this record where possible.

The ALTM 1225 (SN#99d118) lidar instrument has the following specifications: operating altitude = 410-2,000 m AGL; maximum

laser pulse rate = 25 kHz; laser scan angle = variable from 0 to +/-20deg from nadir; scanning frequency = variable, 28 Hz

at the 20deg scan angle; and beam divergence: narrow = 0.2 milliradian (half angle, 1/e). The ALTM 1225 does not digitize and

record the waveform of the laser reflection, but records the range and backscatter intensity of the first and last laser

reflection using a constant-fraction discriminator and two Timing Interval Meters (TIM).

ALTM elevation points are computed using three sets of data: laser ranges and their associated scan angles, platform position

and orientation information, and calibration data and mounting parameters (Wehr and Lohr, 1999). Global Positioning System

(GPS) receivers in the aircraft and on the ground provide platform positioning. The GPS receivers record pseudo-range and

phase information for post-processing. Platform orientation information comes from an Inertial Measurement Unit (IMU)

containing three orthogonal accelerometers and gyroscopes. An aided-Inertial Navigation System (INS) solution for the

aircraft's attitude is estimated from the IMU output and the GPS information.

Wehr, A. and U. Lohr, 1999, Airborne laser scanning - an introduction and overview, ISPRS Journal of Photogrammetry and

Remote Sensing, vol. 54, no.2-3, pp.68-82.

A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/567/supplemental/Scripps_October_2006_Lidar_Long_Beach_to_Mexico_Border.kmz

This data was collected in partnership with Scripps Institution of Oceanography,

The University of California, San Diego. Any conclusions drawn from analysis of this information are not the responsibility

of the Bureau of Economic Geology or the University of Texas at Austin, NOAA, the Office for Coastal Management or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer

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Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer

represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

There was no metadata record provided along with this data set, therefore the horizontal accuracy information is unknown.

However, to provide some idea of the horizontal accuracy for a comparable data set, the horizontal accuracy information provided below,

was gleaned from the metadata record for this same project, for data collected in March of 2006.

The lidar data is estimated to have a horizontal error of less than or equal to 0.50 m from comparison between kinematic GPS

road survey and a 1m resolution grey-scale image generated from the lidar backscatter intensity data. Kinematic GPS data were

superimposed on the lidar backscatter image and examined for any mismatch between the horizontal position of the ground GPS

and the corresponding features on the lidar image. Horizontal agreement between the ground kinematic GPS and the lidar was within

the resolution of the 1m -resolution backscatter image.

There was no metadata record provided along with this data set, therefore the vertical accuracy information is unknown.

However, to provide some idea of the vertical accuracy for a comparable data set, the vertical accuracy information provided below,

was gleaned from the metadata record for this same project, for data collected in March of 2006.

The March 2006 lidar data were compared to the 1998 ATM LIDAR data to determine offsets in the vertical position. The ATM survey

points were estimated to have a vertical accuracy of +/- 15 cm. The March 2006 lidar data set was sorted to find data points that

fell within 0.5 m of an ATM LIDAR survey point along piers in the survey area. The mean elevation difference between the elevation

differences between the March 2006 survey and the ATM survey were used to estimate and remove TIM1 and TIM2 elevation biases from

each lidar flight. The standard deviation of these elevation differences provided estimates of the lidar precision. After bias

adjustment the mean lidar elevations had a vertical accuracy of 0.10 m.

Data were edited by an automated method to remove obvious outliers above a threshold of 150m.

Not Applicable