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Short Citation:
OCM Partners, 2024: 2015 Univ of Texas BEG Topobathy Lidar: Lower Texas Coast, https://www.fisheries.noaa.gov/inport/item/51960.

Item Identification

Title: 2015 Univ of Texas BEG Topobathy Lidar: Lower Texas Coast
Short Name: tx2015_univ_tx_lwr_cst_m6291_metadata
Status: Completed
Publication Date: 2014-08-25
Abstract:

This data set contains LAS v. 1.2 format all points data from the Lower Texas Coast. The data were collected in winter, 2015 using the Bureau of Economic Geology’s airborne system (Chiroptera)which can collect topographic lidar data, shallow bathymetric lidar data, and natural color/color infrared imagery. The X, Y, and Z point data are generated by combining laser range and aircraft attitude data collected using an airborne light detection and ranging (lidar) instrument with once-per-second data collected using geodetic quality (dual phase) Global Positioning System (GPS) airborne and ground-based receivers. The equipment was installed in a twin engine Partenavia P68 aircraft (tail number N300LF) owned and operated by Aspen Helicopters, Inc., and operated locally out of Aransas County Airport in Rockport, Texas.

Purpose:

The Bureau of Economic Geology (BEG) at the University of Texas at Austin (UT) used airborne lidar to provide terrain elevation data of select areas along the lower Texas coast. The primary goal of the project is to provide high-resolution topographic lidar data and aerial photography of colonial waterbird rookery islands. The lidar data will be used by the Oil Spill Program at the Texas General Land Office.

Supplemental Information:

System Information

The Chiroptera LiDAR system was developed and manufactured by Airborne Hydrography AB (AHAB). The topographic LiDAR scanner operates at a wavelength of 1 um, a pulse rate as high as 400 kHz, and swath width of 28 to 40 degrees. It can operate to a maximum height of about 1500 m, allowing the system to be used to rapidly scan large areas with a range accuracy of about 2 cm over a flat target. The bathymetric LiDAR scanner operates at a shorter wavelength (0.5 um) and a lower pulse rate (36 kHz). The shorter wavelength allows the laser to penetrate water of reasonable clarity. After the laser reflects off the bottom surface and back to the source, the transit-time delay between water-surface and water bottom reflections can be used to determine water depths to a flat-bottom accuracy of about 15 cm. Also mounted in the Chiroptera chassis is a Hasselblad DigiCAM 50 megapixel natural color or color infrared camera that acquires frame images at a resolution of 8,176 by 6,132 pixels.

The BEG's aerial surveying capabilities also includes "Goliath," a fast and secure mobile data-storage and -processing system. Its two 40-terabyte (TB) RAID 5 arrays speed the transfer of field data by a factor of 10 over conventional storage systems while providing full redundancy to ensure data integrity. Goliath was designed and assembled to meet specific requirements of the Chiroptera lidar instrument and hyperspectral camera system. Operating simultaneously, these components generate high-resolution data at the rate of about 1.5TB per 2-hour flight. Goliath has been ruggedized for transport and field deployment and enables the research team to remain in the field for the duration of the projectsometimes as long as a week or more. More importantly, the new system allows researchers to visualize and verify the quality of collected data each field day, ensuring adequate areal coverage and optimal data quality.

Keywords

Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY > SEAFLOOR TOPOGRAPHY
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION
ISO 19115 Topic Category
elevation
UNCONTROLLED
None all-points
None beach
None erosion
None island
None shoreline

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > TEXAS
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > SEA FLOOR

Instrument Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Instrument Keywords
LIDAR > Light Detection and Ranging

Platform Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Platform Keywords
Airplane > Airplane

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: Elevation
Maintenance Frequency: None Planned
Data Presentation Form: Point Cloud (Digital)
Entity Attribute Detail Citation:

Bureau of Economic Geology, University of Texas at Austin, 2015.

Distribution Liability:

These data were collected for the purpose of creating a 2015 digital elevation model of the Lower Texas Coast. Any conclusions drawn from analysis of this information are not the responsibility of the Bureau of Economic Geology, the University of Texas at Austin, NOAA, the Office for Coastal Management or its partners.

Data Set Credit: Research staff of the Coastal Studies group, Near Surface Observatory, Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin. This project was supported by grant no. 13-438-000-7897 from the General Land Office of Texas to the BEG. Thomas A. Tremblay served as the principal investigator. The project was funded through the Oil Spill Program., Bureau of Economic Geology, University of Texas at Austin

Support Roles

Data Steward

CC ID: 738904
Date Effective From: 2018
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Distributor

CC ID: 738905
Date Effective From: 2018
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Metadata Contact

CC ID: 738906
Date Effective From: 2018
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Point of Contact

CC ID: 738907
Date Effective From: 2018
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1139750
W° Bound: -97.50223
E° Bound: -95.758178
N° Bound: 28.733288
S° Bound: 26.043571

Extent Group 1 / Time Frame 1

CC ID: 1139749
Time Frame Type: Discrete
Start: 2015-01-29

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for custom or bulk downloads.

Data Access Constraints:

None

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: 738911
Start Date: 2018
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6291
Distributor:
File Name: Customized Download
Description:

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

Compression: Zip

Distribution 2

CC ID: 738912
Start Date: 2018
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6291/index.html
Distributor:
File Name: Bulk Download
Description:

Bulk download of data files in LAZ format, geographic coordinates, orthometric heights.

File Type (Deprecated): LAZ
Distribution Format: LAS/LAZ - LASer
Compression: Zip

URLs

URL 1

CC ID: 738900
URL: https://coast.noaa.gov/
Name: NOAA's Office for Coastal Management (OCM) website
URL Type:
Online Resource
File Resource Format: HTML
Description:

Information on the NOAA Office for Coastal Management (OCM)

URL 2

CC ID: 738901
URL: https://coast.noaa.gov/dataviewer/#/
Name: NOAA's Office for Coastal Management (OCM) Data Access Viewer (DAV)
URL Type:
Online Resource
File Resource Format: HTML
Description:

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

URL 3

CC ID: 738902
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6291/supplemental/tx2015_univ_tx_lwr_tx_cst_m6291.kmz
Name: Browse graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

Data Quality

Horizontal Positional Accuracy:

Selected portions from each lidar data set were used to generate a 1m x 1m digital elevation model (DEM). Data estimated to have a horizontal accuracy of 0.01-0.05m 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. Opposing flight lines crossing the calibration target, roads within the survey area, and buildings with slanted roofs are examined to remove roll, pitch, and heading errors. Several iterations of adjustments were made to minimize these errors caused by IMU misalignment.

Vertical Positional Accuracy:

Ground GPS surveys were conducted near the lidar survey area to acquire ground truth information to refine the processing calibration file to remove elevation biases. The ground survey points are estimated to have a vertical accuracy of 0.05-0.10m. Roads or runways, which are typically flat areas with an unambiguous surface, were surveyed using kinematic GPS techniques. The lidar data set is sorted to find data points that fall within 1 m of a ground GPS survey point. In the project calibration file, slant range correction is adjusted to remove the elevation biases. The standard deviation of the final elevation differences provides estimates of the lidar precision. Topographic lidar RMS for Lower Texas Coast survey is 0.079 m.

Completeness Report:

Complete. The lidar files were flown at a density to support a maximum final post spacing of greater than 4 points per square meter over the ground.

Conceptual Consistency:

This lidar dataset is a topographic survey conducted of the Lower Texas Coast. These data were collected and processed by the Bureau of Economic Geology, The University of Texas at Austin for the Texas General Land Office.

Lineage

Sources

raw Chiroptera and GPS files

CC ID: 1139743
Extent Type: Discrete
Extent Start Date/Time: 2015-01-29
Source Contribution:

raw lidar data from Chiroptera

Ground GPS base stations

Process Steps

Process Step 1

CC ID: 1139744
Description:

Preparation and Data acquisition

Chiroptera system is installed in aircraft. GPS to laser offset values are measured using a survey grade Total Station (if first time installation). System is turned on using ground AC power connection to the aircraft for system check. Aircraft GPS receiver is turned on to start data collection. The pre-determined flight plan is uploaded to the Flight Management software. Ground GPS base stations are setup on geodetic reference points (with known precise Northing, Easting, and Elevation information) in or near the survey area. GPS receivers are set for continuous 1 second data collection rate. Aircraft GPS and Base GPS information needs to overlap each other for the duration of the survey flight. Aircraft takes off to begin the survey mission. Pilot follows the flight altitude, speed and the flight lines as directed by the flight plan. Raw laser point cloud data is collected with external solid state hard drives in the Chiroptera. High resolution raw images are collected using integrated medium format camera. VGA low resolution images are collected for operator and post-processing reference. GPS and attitude (INS) information is collected on an external storage device. Airborne survey is completed after all flight lines are flown.

Process Date/Time: 2015-01-29 00:00:00

Process Step 2

CC ID: 1139745
Description:

Data Download and Preliminary Field Processing

All laser data and raw image files are downloaded to the field computer using its internal drive enclosures. GPS and INS data are downloaded using USB3.0 connections to the field computer. Preliminary GPS processing is completed by merging base GPS receiver with the remote to create a GPS trajectory (GrafNav). The preliminary GPS trajectory is combined with attitude information in AEROoffice to create a 7-parameter (TXYZ,roll,pitch,yaw) navigation file. The navigation solution is used to reference each laser pulse return with the 7-paramater information in LSS. Laser point cloud data is output by flight line in multiple segments. Point cloud data is examined to determine quality of the data coverage (i.e. sufficient overlap of flight lines and point spacing).

Process Date/Time: 2015-01-29 00:00:00

Process Step 3

CC ID: 1139746
Description:

Post-Processing

Upon return from the survey area, all files are transferred from the field computer to an in-house server. Compute base station coordinates using National Geodetic Survey's (NGS) Online Positioning User Service (OPUS). Setup project in AEROoffice software and covert Chiroptera GPS files to binary Novatel GPS files. Convert aircraft GPS file and base station GPS files to GrafNav compatible format. Compute merged aircraft trajectory using GrafNav software. Solutions for base station coordinates and aircraft trajectories are in NAD83. Combine precise trajectories with aircraft attitude information in AEROoffice to create final precise 7-parameter navigation file (TXYZ,roll,pitch,yaw). Laser point data are generated in AHAB processing software Lidar Survey Studio (LSS) combining navigation file information and laser data. LSS also requires a calibration, processing settings, and system configuration files. Laser point data is output from LSS in LAS v1.2 format (a binary file format). A condition is set in LSS to output data in the proper UTM zone and hemisphere. The resultant points are referenced to the Geographic NAD83 horizontal datum and height above the NAD83 ellipsoid. The TerraScan utility of MicroStation was used to concatenate flight line files and to clean data of miscellaneous returns (such as clouds, reflections, long returns, etc).

The LAS data files are parsed into 1x1 km tiles (plus 20m buffer) using the LAStools script lastile. This process created 68 tiles. The 2012A geoid model was used to adjust the elevation data from ellipsoidal to orthometric heights (NAVD88) using a LAStools script called lasheight. The LAS input files are classified into 2 categories 1) ground and 2) everything else (ie. vegetation, power lines, buildings, etc.) using the LAStools script lasground. Create index map shapefile and KML file representing center of each 1x1 km tile with file name for referencing.

Process Date/Time: 2015-08-13 00:00:00

Process Step 4

CC ID: 1139747
Description:

The NOAA Office for Coastal Management (OCM) received 95 files in las format from UT BEG. The files contained elevation and intensity measurements along the coast of Texas. The data were in UTM Zone 14 NAD83 coordinates and NAVD88 (Geoid12A) elevations in meters. The data were classified as: 9 (ground), 13 (low vegetation), 14 (medium vegetation), 15 (high vegetation) . OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:

1. The LAStools software scripts lasinfo and lasvalidate, were run on the las files to check for errors.

2. The LAStools software script las2las was run to convert the classifications of:

Class 9 (ground) to Class 2 (ground)

Class 13, 14, 15 (low/medium/high vegetation) to Class 1 (unclassified) - these classes were converted due to the fact that many points with these classifications were actually structures.

3. Internal OCM scripts were run on the las files to convert from UTM Zone 14 NAD83 coordinates to geographic NAD83 coordinates, from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 12A model, to assign the geokeys, and zip the data to database and to http.

Process Date/Time: 2018-02-20 00:00:00
Process Contact: Office for Coastal Management (OCM)

Catalog Details

Catalog Item ID: 51960
GUID: gov.noaa.nmfs.inport:51960
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2018-03-07 11:04+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2023-10-17 16:12+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