March 2006 Lidar Point Data of Southern California Coastline: Long Beach to US/Mexican
This data set contains lidar point data (Geodetic Coordinates) from a strip of Southern
California coastline (including water, beach, cliffs, and top of cliffs) from Long
Beach to the US/Mexico border. The data set was created by combining 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 Bureau of Economic Geology, the University of Texas at Austin owns and operates
an ALTM 1225 system (serial number 99d118). 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 on 24 and 25 March 2006;
Julian Days 08306 and 08406 (see Lineage, Source_Information, Source_Contribution
for pass information). 99d118 instrument settings for these flights were; laser pulse
rate: 25kHz, scanner rate: 26Hz, scan angle: +/- 20deg, beam divergence: narrow, altitude:
300-600m AGL, and ground speed: 95-120kts. Two GPS base stations were operating during
each day of the survey, Point Loma and San Onofre on 08306 and Seal Beach and San
Onofre on 08406 (see Lineage, Source_Information, and Source Contribution for coordinates).
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.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
||Julie Thomas/Randy Bucciarelli
SCBPS/CDIP, Scripps Institution of Oceanography
Documentation links not available.
- Southern California Beach Processes Study (SCBPS)/Coastal Data Information Program
(CDIP) part of Scripps Institution of Oceanography (SIO) in cooperation with Bureau
of Economic Geology, University of Texas at Austin.
- Scripps Institute of Oceanography
- Center for Space Research, University of Texas at Austin
- Bureau of Economic Geology, University of Texas at Austin
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||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.
||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.
||2006-03-24 to 2006-03-25
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- point file
- San Diego
- Pacific Ocean
| Use Constraints
|| No constraint information available
|| Fee information not available.
Raw lidar data output from ALTM 1225, SN#99D118
- Description of Source: Source Contribution: Raw lidar files. 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 Source Type: digital file
- Temporal extent used:
2006-03-24 to 2006-03-25
Air and Ground GPS files from 08306 and 08406
- Description of Source: Source Contribution: GPS data. 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) Source Type: digital file
- Temporal extent used:
2006-03-24 to 2006-03-25
|| Lineage statement not available.
- Bureau of Economic Geology, University of Texas at Austin
- DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
| Processing Steps
- 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.
- The NOAA Coastal Services Center (CSC) received files in ASCII format. The files contained
LiDAR intensity and elevation measurements. CSC 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.
- The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp
transfer from the NOAA Coastal Services Center. The data are
currently being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS
or LAZ format. The LAS format is an industry standard for LiDAR data developed by
the American Society of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless
compressed version of LAS developed by Martin Isenburg (http://www.laszip.org/). The
data are exclusively in geographic coordinates (either NAD83 or ITRF94). The data
are referenced vertically to the ellipsoid (either GRS80 or ITRF94), allowing for
the ability to apply the most up to date geoid model when transforming to orthometric
Metadata Last Modified: 2013-06-11
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