March 2006 Lidar Point Data of Southern California Coastline: Long Beach to US/Mexican Border

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Simple download of data files.

Date that the source FGDC record was last modified.

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

Partial upload of Positional Accuracy fields only.

Partial upload to move data access links to Distribution Info.

air and ground GPS files

base station coordinates Easting, Northing, HAE in NAD83, Zone 11 (Latitude, Longitude):

Seal Beach (SEAL) = 399190.210, 3733584.054, -27.287 (N 33 44 15.03814, W 118 05 17.77225)

San Onofre (SANO) = 447430.058, 3693036.854, -5.193 (N 33 22 31.08745, W 117 33 54.55130)

Point Loma (LOMA) = 477399.573, 3614791.280, 90.855 (N 32 40 13.99848, W 117 14 27.74927)

| Type of Source Media: digital file

raw lidar data from ALTM 1225 (all times UTC)

08306

Pass A (Carlsbad to Mexico) = 18:41-19:14

Pass B (Mexico to Point Loma) = 19:17-19:24

Pass C (Point Loma to Mexico) = 19:29-19:35

Pass D (Point Loma to Dana Point) = 20:06-20:43

Pass E (Dana Point to La Jolla) = 20:49-21:16

Pass F (La Jolla to Dana Point) = 21:39-22:26

Pass G (Dana Point to Carlsbad) = 22:13-22:26

2 Calibration Passes = 21:19-21:25

08406

Pass H (Newport Beach to Long Beach) = 20:44-20:56

Pass I (Long Beach to Dana Point) = 21:00-21:17

Pass J (Dana Point to Long Beach) = 21:31-21:47

Pass K (Long Beach to Dana Point) = 21:51-22:08

Pass L (Dana Point to Newport Beach) = 22:12-22:19

2 Calibration Passes = 22:24-22:30

| Type of Source Media: digital file

GPS and XYZ-Point Data Processing

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.

Using the GEOID99 geoid 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.

Processing occurred 20060324-20060726.

Created initial metadata

The NOAA Office for Coastal Management (OCM) received files in ASCII format. The files contained LiDAR intensity

and elevation measurements. OCM performed the following

processing on the data to make it available within the LiDAR Data Retrieval Tool (LDART)

1. Data returned to ellipsoid heights from NAVD88, using GEOID99.

2. Data converted to LAS format.

3. The LAS data were sorted by latitude and the headers were updated.