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OCM Partners, 2023: April 2005 Lidar Point Data of Southern California Coastline: Long Beach to US/Mexican Border,

Item Identification

Title: April 2005 Lidar Point Data of Southern California Coastline: Long Beach to US/Mexican Border
Short Name: scripps_20050404_m52_metadata
Status: Completed
Publication Date: 2005-07-28

This data set contains lidar point data (latitude/longitude) 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 Observer (tail number N6602L) owned and operated by Aspen Helicopter, Inc. The lidar

data set described by this document was collected on 4 and 8 April 2005; Julian Days 09405 and 09805 (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: 900-1100m AGL,

and ground speed: 100-125kts. Three GPS base stations (Seal Beach, Dana Point, and Point Loma, see Lineage,

Source_Information, Source_Contribution for coordinates) operated 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.

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.



Other Citation Details:

quad names (from north to south): Long Beach, Los Alamitos, Long Beach OE S, Seal Beach, Newport Beach,

Newport Beach OE S, Laguna Beach, San Juan Capistrano, Dana Point, San Clemente, San Onofre Bluff, Las Pulgas Canyon,

Oceanside, San Luis Rey, Encinitas, Del Mar OE W, Del Mar, La Jolla OE W, La Jolla, Point Loma OE W, Point Loma,

Imperial Beach OE W

Supplemental Information:

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 +/-20 deg from nadir; scanning frequency = variable,

28 Hz at the 20 deg 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.


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
None beach
None intensity
None Latitude
None Longitude
None point file
None shoreline

Temporal Keywords

Thesaurus Keyword
None 2005
None April

Physical Location

Organization: Office for Coastal Management
City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Note:

None planned, as needed

Distribution Liability:

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 OCM or its partners.

Data Set Credit: SCBPS/CDIP is jointly funded by the US Army Corps of Engineers and the California Department of Boating and Waterways. The initial data are collected by Bureau of Economic Geology, The University of Texas at Austin: R. Gutierrez and T. Hepner. Center for Space Research, The University of Texas at Austin: A. Neuenschwander. Data are further classified and processed by the SCBPS group, located at the Scripps Institution of Oceanography.

Support Roles

Data Steward

CC ID: 686644
Date Effective From: 2005-07-28
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


CC ID: 686646
Date Effective From: 2005-07-28
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Metadata Contact

CC ID: 686647
Date Effective From: 2005-07-28
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Point of Contact

CC ID: 686645
Date Effective From: 2005-07-28
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1138530
W° Bound: -118.205345
E° Bound: -117.128845
N° Bound: 33.768786
S° Bound: 32.562486

Extent Group 1 / Time Frame 1

CC ID: 1138529
Time Frame Type: Range
Start: 2005-04-04
End: 2005-04-08

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Data Access Procedure:

This data can be obtained on-line at the following URL:


Data Access Constraints:


Data Use Constraints:

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.

Distribution Information

Distribution 1

CC ID: 742577
Download URL:
File Name: Customized Download

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

Distribution 2

CC ID: 742578
Download URL:
File Name: Bulk Download

Simple download of data files.



CC ID: 742580
URL Type:
Online Resource


CC ID: 742581
URL Type:
Online Resource

Activity Log

Activity Log 1

CC ID: 686668
Activity Date/Time: 2017-03-20

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 686667
Activity Date/Time: 2017-11-14

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

Activity Log 3

CC ID: 718609
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 742579
Activity Date/Time: 2018-03-13

Partial upload to move data access links to Distribution Info.

Data Quality

Horizontal Positional Accuracy:

Selected portions from each lidar data set (last return only) were used to generate

a 1m x 1m digital elevation model (DEM). Data estimated to have a horizontal accuracy of 0.01-0.03m from ground surveys

using kinematic GPS techniques were superimposed on the lidar DEM and examined for any mismatch between the horizontal

position of the ground GPS and the corresponding feature on the lidar DEM. Horizontal agreement between the ground kinematic

GPS and the lidar was within the resolution of the 1m x 1m DEM.

Vertical Positional Accuracy:

The April 2005 lidar data were compared to the 1998 ATM LIDAR data to determine offsets

in the vertical position. The ATM survey points are estimated to have a vertical accuracy of +/- 15 cm. The April 2005

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 April 2005 survey and the ATM survey was used to estimate and

remove an elevation bias from the lidar. The standard deviation of these elevation differences provides estimates of the

lidar precision. The bias was removed so that mean lidar elevations have a vertical accuracy of 0.10 m.

Completeness Report:

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

Conceptual Consistency:

Not Applicable



Air and Ground GPS files from 27204, 27304, and 27404

CC ID: 1138522
Publish Date: 2005-05-08
Extent Type: Range
Extent Start Date/Time: 2005-04-04
Extent End Date/Time: 2005-04-08
Source Contribution:

air and ground GPS files

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

Seal Beach (SEAL) = 399189.009, 3733584.462, -27.9778 (N 33 44 15.0510, W 118 5 17.8191)

Dana Point (DANA) = 434087.529, 3702982.315, 52.1756 (N 33 27 51.3542, W 117 42 33.5246)

Point Loma (LOMA) = 477398.387, 3614791.668, 90.1348 (N 32 40 14.01098, W 117 14 27.79485)

| Type of Source Media: digital file

Raw lidar data output from ALTM 1225

CC ID: 1138523
Publish Date: 2005-04-08
Extent Type: Range
Extent Start Date/Time: 2005-04-04
Extent End Date/Time: 2005-04-08
Source Contribution:

raw lidar data from ALTM 1225 (all times UTC)


Pass A (Oceanside to Dana Point) = 19:19-19:36

Pass B (Dana Point to Mexico) = 19:39-20:17

Pass C (Point Loma to Mexico) = 20:28-20:34

Pass D (Mexico to Dana Point) = 20:36-21:00 and 21:12-21:35

Pass E (Oceanside to La Jolla) = 21:45-21:59

Pass F (La Jolla to Oceanside) = 22:02 to 22:14

Calibration Passes = 21:02-21:11


Pass G (Oceanside to Long Beach) = 21:37-22:20

Pass H (Long Beach to Dana Point) = 22:23-22:41

Pass I (Dana Point to Long Beach) = 22:45-23:06

Pass J (Long Beach to Dana Point) = 23:12-23:29

Calibration Passes = 23:34-23:47

| Type of Source Media: digital file

Process Steps

Process Step 1

CC ID: 1138524

GPS and XYZ-Point Data Processing

The National Geodetic Survey's PAGES-NT software was used to compute double differenced, ionospherically corrected,

static GPS solutions for each GPS base station with precise ephemeredes from the International GPS Service (IGS).

As part of the solution tropospheric zenith delays were estimated and L1 and L2 phase biases were fixed as integers.

Aircraft trajectories were estimated with respect to all base stations using National Geodetic Survey's Kinematic and

Rapid-Static Software (KARS) software. Trajectories were double-differenced, ionospherically corrected, bias-fixed GPS

solutions computed with precise IGS ephemeredes. Coordinates for base stations and trajectories were in the International

Terrestrial Reference Frame of 2000 (ITRF00). The aircraft trajectory were transformed from the ITRF00 to North American

Datum of 1983 (NAD83) using the Horizontal Time Dependent Positioning (HDTP) software (Snay, 1999)

The 1Hz GPS trajectory and 50Hz aircraft inertial measurement unit (IMU) data were combined in Applanix's POSProc

version 2.1.4 to compute an aided inertial navigation solution (INS) and a 50Hz, smoothed best estimate of

trajectory (SBET) for day 09405. On the second day of data collection (09805), due to an equipment problem, the IMU data

was recorded with random data gaps onto the ALTM1225 hard drive. Because of these data gaps, the post-processed INS and

SBET for 09805 was judged not acceptable. The 1Hz aircraft trajectory computed with KARS and the real-time, aided

INS solution from POS-AV provided better results. The SBET (09405) and KARS trajectory (09805), laser range observations,

scanner position information, and GPS/internal clock files were processed in Realm 2.27 software suite to generate lidar

data points in the Universal Transverse Mercator (UTM) projection.

Lidar point data were compared to GPS ground survey data and 1998 ATM lidar data to estimate lidar instrument calibration

parameters: roll and pitch biases, scanner scale factor, and first/last return elevation biases. An iterative,

least-squares methodology was used to estimate calibration parameters so as to minimize differences between lidar and

ground GPS data. Samples of lidar data were used to create high-resolution digital elevation models (DEM); these DEM

were inspected for horizontal or vertical anomalies.

After system calibration and initial quality control step, the adjusted lidar x,y,z-point data were generated by REALM

software and output 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. Each record contains 9 columns of data: time tag (seconds in the GPS week),

first return Easting, first return Northing, first return NAVD88, last return Easting, last return Northing,

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).

Process Date/Time: 2005-04-04 00:00:00

Process Step 2

CC ID: 1138525

Data Classification Processing

The classification of the lidar point data was accomplished with algorithms developed at the Center for Space Research

and implemented by C++ code running on PC computer using the LINUX operating system.

The ASCII lidar files were converted into binary and concatenated into a processing database. Data were separated into

ground and non-ground points using a lower envelope follower (LEF). A lower envelope detector is an electronic circuit

used to recover information in an Amplitude Modulated (AM) signal and the concept was adapted to the problem of

extracting the ground surface from the lidar signal by creating a computer analog: the lower envelope follower (LEF)

The LEF was used to detect ground points, or seeds, which include pixels located on open ground or on the ground surface

beneath vegetation penetrated by the laser, but excludes buildings and vegetation.

The LEF operation does not detect some ground surface areas with low gradients, so detected ground pixels are augmented

using an adaptive gradient flood fill procedure. The adaptive threshold value is determined as a function of surface

roughness and topographic relief.

The adaptive gradient flood fill procedure results in a ground mask which is used to parse individual lidar points

into ground or non-ground files. In some instances, hand editing is required to ensure accuracy of the ground mask.

This includes the addition of seed points along topographic ridges or removal of buildings not detected during previous


The 9-column binary dataset was pushed through the ground mask and each lidar point is classified as either ground

or non-ground depending on its elevation with respect to a threshold above or below the estimated ground surface.

Buildings are included as non-ground points. The final ground-only data points were parsed converted back into ASCII format.

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). The final step was parsing the data into quarter quadrangles.

Processing occurred 20050404-20050728.

Process Date/Time: 2005-04-04 00:00:00

Process Step 3

CC ID: 1138526

Created initial metadata

Process Date/Time: 2003-04-18 00:00:00

Process Step 4

CC ID: 1138527

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.

Process Date/Time: 2007-07-24 00:00:00

Catalog Details

Catalog Item ID: 50008
GUID: gov.noaa.nmfs.inport:50008
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:23+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2022-03-16
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-16
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-16