March 2003 Lidar Point Data of Southern California Coastline: Dana Point to Point
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 Dana
Point to Point La Jolla. 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 N6602L) owned and operated by Aspen Helicopter, Inc. The lidar data
set described by this document was collected on 28-29 March 2003; Julian Days 08703
and 08803 (see Lineage, Source_Information, Source_Contribution for pass information).
Conditions on both days were clear skies, no fog or low clouds. 99d118 instrument
settings for these flights were; laser pulse rate: 25kHz, scanner rate: 26Hz, scan
angle: +/- 15-20deg, beam divergence: narrow, altitude: 900-1160m AGL, and ground
speed: 90-132kts. Two GPS base stations (Scripps pier and Dana Point, see Lineage,
Source_Information, Source_Contribution for coordinates) were operating during the
survey. 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.
||2003-03-28 to 2003-03-29
|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
- Description of Source: Source Contribution: Raw lidar data files. Raw lidar data from ALTM 1225 08703 4 calibration
passes between 22:22-22:34 UTC Offshore Pass = 22:42-23:28 UTC Buoy passes = 23:46-00:14
UTC 08803 Pass 1 (Carlsbad to Dana Point) = 20:58-21:15 UTC Pass 2 (Dana Point to
Point La Jolla) = 21:17-21:47 UTC 4 calibration passes between 21:52-22:08 UTC Pass
3 (Point La Jolla to Dana Point) = 22:16-22:46 UTC Pass 4 (Dana Point to Point La
Jolla) =22:58-23:12 UTC Source Type: digital file
- Temporal extent used:
2003-03-28 to 2003-03-29
Air and Ground GPS files from 08703 and 08803
- Description of Source: Source Contribution: GPS data. Air and ground GPS files base station coordinates (Easting,
Northing, HAE) in NAD83: Scripps Pier (PIER) = 476093.032, 3636524.941, -25.424 Dana
Point (DANA) = 434087.645, 3702982.251, 52.174 Source Type: digital file
- Temporal extent used:
2003-03-28 to 2003-03-29
|| Lineage statement not available.
- SCBPS/CDIP, Scripps Institution of Oceanography
- DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
| Processing Steps
- 1. Transfer raw ALTM 1225 flight data, airborne GPS data collected at 1 Hz using Ashtech
receiver, and ground-based GPS data collected at 1 Hz using Ashtech and Trimble 4000SSI
receivers to NT workstation. 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). 2. Compute base station coordinates using National Geodetic Survey's PAGES
software. Computed aircraft trajectories for both base stations using National Geodetic
Survey's KINPOS software. Coordinates for base stations and trajectories are in the
International Terrestrial Reference Frame of 2000 (ITRF2000) datum. Trajectories from
both base stations were merged into one. Weighting for trajectory merge is based upon
baseline length (distance from base station) and solution RMS. Transformed trajectory
solution from ITRF2000 to North American Datum of 1983 (NAD83). 3. Use NAD83 trajectories
and aircraft inertial measurement unit data in Applanix's POSProc version 2.1.4 to
compute an optimal 50Hz inertial navigation solution. 4. Substitute the aircraft position
and attitude information from the inertial navigation solution into Realm 2.27. Extract
calibration area data set from lidar point file for quality control and instrument
calibration checks. If necessary, use multiple iterations to adjust calibration parameters
(pitch, roll, and scale) and reprocess sample data set. Determine and apply bias corrections
based upon ground GPS. Then generate entire lidar point file (9-column ASCII file).
5. Use the Geiod99 geoid model to convert from Height Above the GRS80 ellipsoid to
elevations with respect to the North American Vertical Datum 88 (NAVD88). 6. Parse
the 9-column lidar point file into 3.75-minute quarter-quadrangle components. There
are some points in the file that only contain 5-columns. These are points that either
the first or last pulse was not recorded. 7. UTM Easting and Northing were converted
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. 8. The eighteen UTM quarter-quad files were re-organized
into eleven 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. mar03) 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: 2013-05-07
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