Data Management Plan

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

Process Steps:

• 2006-01-01 00:00:00 - GPS and XYZ-Point Data Processing There was no metadata record provided along with this data set, therefore the process description is unknown. However, to provide some idea of plausible processing, the information provided below, was gleaned from the metadata record for a data set from this same project, for data collected in March of 2006. Transfer raw ALTM 1225 flight data (laser ranges with associated scan angle information and IMU data), airborne GPS data collected at 1 Hz using Ashtech receiver, and ground-based GPS data collected at 1 Hz using Ashtech Z-12 receivers to processing computer. Generate decimated lidar point file from above three data sets using Optech's Realm 2.27 software. This is a 9-column ASCII data set with the following format: time tag; first pulse Easting, Northing, HAE; last pulse Easting, Northing, HAE; first pulse intensity; and last pulse intensity. View decimated lidar point file to check data coverage (i.e. sufficient overlap of flight lines and point spacing). Compute base station coordinates using National Geodetic Survey's PAGES-NT software. Compute aircraft trajectories from each base station GPS dataset using National Geodetic Survey's KINPOS software. Solutions for base stations coordinates and aircraft trajectories are in the International Terrestrial Reference Frame of 2000 (ITRF2000). A final aircraft trajectory was computed from a weighted average of the trajectories from the two base stations. Epoch-by-epoch weighting for the individual trajectories was inversely proportional to the baseline length (distance from base station) and solution RMS. Transformed trajectory solution from ITRF2000 to North American Datum of 1983 (NAD83) using the National Geodetic Survey's Horizontal Time Dependent Positioning software (http://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.html). Input NAD83 trajectories and aircraft inertial measurement unit data into Applanix's POSProc version 2.1.4 to compute an optimal 50Hz inertial navigation solution (INS) and smoothed best estimate of trajectory (SBET). Substitute the INS and SBET into Realm 2.27. Generate a set of initial lidar instrument calibration parameters (pitch, roll, scale, and elevation bias) for each lidar flight, then incrementally improve parameters by iteratively comparing a subset of the lidar output to the GPS kinematic ground control. Once the instrument calibration parameters are sufficiently accurate, create the complete lidar point file (9-column ASCII file) for the entire survey area in UTM Zone 11 with elevations being heights above the GRS-80 reference ellipsoid (HAE). The output format from REALM 2.27 was a 9-column ASCII file containing: the second in the GPS week, easting, northing and HAE of the first lidar return, the easting, northing and HAE of the last lidar return, and the laser backscatter intensity of the first and last returns.
• 2006-01-01 00:00:00 - Using the GEOID99 model, heights above the GRS80 ellipsoid were converted to orthometric heights with respect to the North American Vertical Datum of 1988 (NAVD88). Parse the 9-column lidar point file into 3.75-minute quarter-quadrangle components. Convert UTM Easting and Northing to geodetic latitude and longitude with respect to the GRS80 ellipsoid. The conversion was computed using the TMGEOD and TCONPC fortran subroutines written by T. Vincenty (NGS). Each record contains 9 columns of data: time tag (seconds in the GPS week), first return Latitude,first return Longitude, first return NAVD88, last return Latitude, last return Longitude, last return NAVD88, first return intensity, and last return intensity. In some cases either the first or last return values may be missing (5 columns). Latitude and longitude are in decimal degrees with nine significant digits to retain the 0.01m resolution of the UTM coordinates. West longitude is negative and north latitude is positive. The UTM quarter-quad files were re-organized into latitude delineated files. UTM quarter-quads files that were delineated by the same upper and lower latitude bounds were concatenated. The lat-long files were named by the month-year of the survey (e.g. mar06) and the lower latitude bounding the quarter-quad.
• 2003-04-18 00:00:00 - Created initial metadata
• 2011-03-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received the lidar files in ASCII format. The files contained lidar intensity and elevation measurements. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. Data converted from UTM coordinates to geograhic coordinates. 2. Data converted from NAVD88 heights to ellipsoid heights using GEOID03. 3. Data converted from dual return xyz format to xyz text format with return numbers to las format. 4. The LAS data were sorted by latitude and the headers were updated.

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

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