DOC/NOAA/NOS/CSC/CRS > Coastal Remote Sensing Program, Coastal Services Center, National Ocean Service, NOAA, U.S. Department of Commerce
Publication Date:
20061018
Title:
2003 Oahu coastline lidar mapping project
Geospatial Data Presentation Form:
model
Description:
Abstract:
LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning and inertial measurement technologies; LIDAR instruments are able to make highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures and vegetation. This data was collected over a 100 meter swath of the Oahu, Hawaii coastline with a Leica ALS-40 Aerial Lidar Sensor. Multiple returns were recorded for each pulse in addition to an intensity value.
Purpose:
The purpose of this mapping project is to create and
deliver digital terrain models (DTM), to support the
environmental, social, and economic well being of the
coast by linking people, information, and technology. The
data will support the local Coastal Zone Managers in their
decision-making processes
Time Period of Content:
Time Period Information:
Range of Dates/Times:
Beginning Date:
20031021
Ending Date:
20031207
Currentness Reference:
Ground conditions
Status:
Progress:
Complete
Maintenance and Update Frequency:
Unknown
Spatial Domain:
Bounding Coordinates:
West Bounding Coordinate:
-158.28200
East Bounding Coordinate:
-157.64879
North Bounding Coordinate:
21.728400
South Bounding Coordinate:
21.250250
Keywords:
Theme:
Theme Keyword Thesaurus:
EDI Thesaurus
Theme Keyword:
Digital Terrain Model
Theme Keyword:
DTM
Theme Keyword:
Lidar Point Cloud
Theme Keyword:
Lidar
Theme Keyword:
DEM
Theme Keyword:
Digital Elevation Model
Theme Keyword:
elevation and derived products
Theme Keyword:
elevation model
Theme Keyword:
LIDAR
Theme Keyword:
surface model
Place:
Place Keyword Thesaurus:
Geographic Names Information System
Place Keyword:
Hawaii
Place Keyword:
Honolulu
Place Keyword:
Oahu
Access Constraints:
none
Use Constraints:
Any conclusions drawn from analysis of this information are not the responsibility of NOAA or the Coastal Services Center. 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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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 it's limitations.
1. Lidar data was collected and processed in accordance
with FEMA guidance as published in Appendix A,
February, 2002.
2. Lidar data at the interface between the land and ocean
was collected (when possible) during periods when tides
were predicted to be below mean lower low water based
upon NOAA CO-OPS tide predictions for the nearest tidal
station.
3. Lidar data accuracy is in accordance with the National
Standard for Spatial Accuracy (NSSDA). When compared
to 14 GPS static survey points in open non-vegetated areas,
at least 95% of the positions have an error less than or
equal to 28.8 cm (equivalent to root mean square error of
14.7 cm).
Logical Consistency Report:
Compliance with the accuracy standard was ensured by
the placement of GPS ground control prior to the
acquisition of lidar data. The following checks
were performed.
1. The ground control and airborne GPS data stream were
validated through a fully analytical boresight adjustment.
2. The DTM (Digital Terrain Model) data were checked
against the project control.
3. Lidar elevation data was validated through an
inspection of edge matching and visual inspection for
quality (artifact removal).
Completeness Report:
1. EarthData's proprietary software, Checkedb, for
verification against ground survey points.
2. Terrascan, for verification of automated and manual
editing and final QC of products.
Positional Accuracy:
Horizontal Positional Accuracy:
Horizontal Positional Accuracy Report:
The lidar data fully comply with FEMA guidance as
published in Appendix A, February, 2002.
Vertical Positional Accuracy:
Vertical Positional Accuracy Report:
The lidar data fully comply with FEMA guidance as
published in Appendix A, February, 2002 and National
Standard for Spatial Accuracy (NSSDA). When compared
to 14 GPS static survey points in open non-vegetated areas,
at least 95% of the positions have an error less than
or equal to 28.8 cm (equivalent to root mean square error
of 14.7 cm).
Lineage:
Source Information:
Source Citation:
Citation Information:
Originator:
Kevin J. Chappell
Publication Date:
20031105
Title:
Report of Survey - Oahu, Hawaii
Geospatial Data Presentation Form:
diagram
Type of Source Media:
electronic mail system
Source Time Period of Content:
Time Period Information:
Range of Dates/Times:
Beginning Date:
20031104
Ending Date:
20031105
Source Currentness Reference:
Ground Condition
Source Citation Abbreviation:
Ground Control
Source Contribution:
Kevin Chappell, of Terrasurv and under contract to
EarthData International established 30 ground control
points along the coastline of the island of Oahu and within
a blocked area around Honolulu where the 2005 flight was
flown. The points were surveyed using GPS for both
vertical and horizontal oordinate values. The horizontal
datum used was the North American Datum of 1983
(Pacific Plate Fixed Realization, epoch 2002.0). The
vertical datum used was a Local Tidal Datum.
Source Information:
Source Citation:
Citation Information:
Originator:
EarthData Aviation, LLC
Publication Date:
20031207
Title:
Aerial Lidar Acquisition over Coastal Oahu, HI
Geospatial Data Presentation Form:
model
Type of Source Media:
Firewire Drive
Source Time Period of Content:
Time Period Information:
Range of Dates/Times:
Beginning Date:
20031021
Ending Date:
20031207
Source Currentness Reference:
Ground Condition
Source Citation Abbreviation:
Aerial Lidar Acquisition
Source Contribution:
Horizons Inc., was contracted by EarthData
International to collect ALS-40 Lidar data over the coastal
area of Oahu, Hawaii. The project site was flown on
October 21 and November 1, 8, 24, 27, and December 7,
2003, using aircraft 2636P. Lidar data was captured using
an ALS-40 Lidarsystem, including an inertial measuring unit
(IMU) and a dual frequency GPS receiver. Lidar was
obtained at an altitude of 1,524 meters (5,000 feet) above
mean terrain, at an average airspeed of 110 knots. Sensor
pulse rate was set at 20,000 Hz with a field of view of 20
degrees and a scan rate of 19 Hz. Average swath width of
the collected raw lines is 537 meters. Point spaing was 2
meters. Lidar data was recorded in conjunction with
airborne GPS and IMU; the stationary GPS receiver was
positioned over a control point located at the airport.
Recorded digital data was shipped via external hard drive
to the production facility for processing. During airborne
data collection, an additional GPS receiver was in
constant operation over a published National Geodetic
Survey (NGS) control point at at Honolulu Airport. The
coordinate value for temporary control point "PHNL" was
determined by a network adjustment to CORS stations
EHN1 and HNLC, both of which were tied to the project
control network. During the data acquisition, the receivers
collected phase data at an epoch rate of 1 Hz.
All GPS phase data was post processed with continuous
kinematic survey techniques using "On the Fly" (OTF)
integer ambiguity resolution. The GPS data was
processed with forward and reverse processing algorithms.
An adjustment was made to the ellipsoid height of the
published point by Terrasurv to reflect Local Tidal
Elevation. The results from each process, using the data
collected at the airport, were combined to yield a single
fixed integer phase differential solution of the aircraft
trajectory.
Process Step:
Process Description:
EarthData has developed a unique method for processing
lidar data to identify and remove elevation points falling
on vegetation, buildings, and other aboveground
structures. The algorithms for filtering data were utilized
within EarthData's proprietary software and commercial
software written by TerraSolid. This software suite of tools
provides efficient processing for small to large-scale,
projects and has been incorporated into ISO 9001
compliant production work flows. The following is a
step-by-step breakdown of the process.
1. Using the lidar data set provided by EarthData, the
technician performs calibrations on the data set.
2. Using the lidar data set provided by EarthData, the
technician performed a visual inspection of the data to
verify that the flight lines overlap correctly. The technician
also verified that there were no voids, and that the data
covered the project limits. The technician then selected a
series of areas from the data set and inspected them
where adjacent flight lines overlapped. These overlapping
areas were merged and a process which utilizes 3-D
Analyst and EarthData's proprietary software was run to
detect and color code the differences in elevation values
and profiles. The technician reviewed these plots and
located the areas that contained systematic errors or
distortions that were introduced by the lidar sensor.
3. Systematic distortions highlighted in step 2 were
removed and the data was re-inspected. Corrections
and adjustments can involve the application of angular
deflection or compensation for curvature of the ground
surface that can be introduced by crossing from one type
of land cover to another.
4. The lidar data for each flight line was trimmed in batch
for the removal of the overlap areas between flight lines.
The data was checked against a control network to
ensure that vertical requirements were maintained.
Conversion to the client-specified datum and projections
were then completed. The lidar flight line data sets were
then segmented into adjoining tiles for batch processing
and data management.
5. The initial batch-processing run removed 95% of points
falling on vegetation. The algorithm also removed the
points that fell on the edge of hard features such as
structures, elevated roadways and bridges.
6. The operator interactively processed the data
using lidar editing tools. During this final phase the
operator generated a TIN based on a desired thematic
layers to evaluate the automated classification performed
in step 5. This allowed the operator to quickly re-classify
points from one layer to another and recreate the TIN
surface to see the effects of edits. Geo-referenced images
were toggled on or off to aid the operator in identifying
problem areas. The data was also examined with an
automated profiling tool to aid the operator in
the reclassification.
6. The final DEM was written to an ESRI grid format (.flt).
7. The point cloud data were also delivered in LAS format.
Source Used Citation Abbreviation:
Lidar
Process Date:
20050902
Source Produced Citation Abbreviation:
Lidar
Process Contact:
Contact Information:
Contact Organization Primary:
Contact Organization:
EarthData International
Contact Person:
Harold Rempel
Contact Position:
Senior Project Manager
Contact Address:
Address Type:
mailing and physical address
Address:
7320 Executive Way
City:
Frederick
State or Province:
Maryland
Postal Code:
21704
Contact Voice Telephone:
301-948-8550
Contact Electronic Mail Address:
metadata@earthdata.com
Process Step:
Process Description:
The NOAA Coastal Services Center (CSC) received LAS files containing the point cloud elevation data from Earth Data, Inc. CSC performed the following processing on the data to make it available within the Lidar Data Retrieval Tool (LDART):
1. Variable length header records were added to the LAS files to identify projection, datum and sort order.
2. The LAS files were sorted by latitude.
Process Date:
20050927
Process Contact:
Contact Information:
Contact Organization Primary:
Contact Organization:
Coastal Remote Sensing Program
Contact Position:
TCM Project Scientist
Contact Address:
Address Type:
mailing and physical address
Address:
2234 South Hobson Avenue
City:
Charleston
State or Province:
South Carolina
Postal Code:
29405
Country:
United States
Contact Voice Telephone:
(843) 740-1200
Contact Electronic Mail Address:
csc@csc.noaa.gov
Process Step:
Process Description:
The NOAA National Geophysical Data Center (NGDC) received Lidar data files on external harddrive. The disk contains LiDAR data from the NOAA Coastal Services Center. This data is currently being served via LDART at http://www.csc.noaa.gov/ldart . This data can be used to re-populate the system. The data are provided on this disk in two forms, ascii x,y,z data and also in LAS format. LAS format is an industry standard for serving LiDAR data. The data are exclusively in geographic coordinates, however, the datums used vary. Most is NAD 83, however some is in ITRF. Vertical systems include both ellipsoid (ITRF and NAD 83) and NAVD 88. For NAVD 88 values, Geiod 03 is primarily used; however, data received in NAVD 88 prior to 2003 was processed using Geoid 99.
Process Date:
20060103
Process Contact:
Contact Information:
Contact Organization Primary:
Contact Organization:
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Any conclusions drawn from analysis of this information
are not the responsibility of NOAA or the Coastal Services
Center.
Custom Order Process:
This data can be obtained on-line at the following URL:
http://www.csc.noaa.gov/ldart.
Distributor:
Contact Information:
Contact Organization Primary:
Contact Organization:
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Contact Person:
Kelly Stroker
Contact Address:
Address Type:
Mailing and Physical Address
Address:
NOAA/NESDIS/NGDC E/GC1 325 Broadway
City:
Boulder
State or Province:
CO
Postal Code:
80305-3328
Country:
USA
Contact Voice Telephone:
(303) 497-4603
Contact TDD/TTY Telephone:
(303) 497-6958
Contact Facsimile Telephone:
(303) 497-6513
Contact Electronic Mail Address:
kelly.stroker@noaa.gov
Hours of Service:
7:30-5:00 Mountain
Contact Instructions:
Contact Data Center
Distribution Liability:
Disclaimer While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
Custom Order Process:
The National Geophysical Data Center serves as the archive for this LIDAR data. NGDC should only be contacted for this data if it cannot be obtained from NOAA Coastal Services Center.
