2009 US Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) Topographic Lidar: South Texas Coast

This Light Detection and Ranging (LiDAR) classified (ASPRS LAS classifications) dataset is a topographic survey conducted for the West

Texas Aerial Survey 2009 project. This data was produced for the US Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry

Technical Center of Expertise (JALBTCX). The LiDAR point cloud was flown at a density sufficient to support a maximum final post

spacing of 1 point per meter. 3001 International Inc. acquired 81 flightlines between February 3, 2009 and April 23, 2009. The West

Texas Aerial Survey 2009 was collected under the guidance of a Professional Mapper/Surveyor. The area of coverage includes portions

of the coastline in the following counties: Aransas, Brazoria, Calhoun, Cameron, Kenedy, Kleberg, Matagorda, Nueces, San Patricio,

and Willacy.

Original contact information:

Contact Org: Northrop Grumman (formerly 3001 International Inc.)

Title: LiDAR Department

Phone: (985) 661 - 3001

The West Texas Aerial Survey 2009 project will support the US Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical

Center of Expertise (JALBTCX) collection of data representing the post-hurricane condition of the beaches, barrier islands, and lakeshores

along the coasts of Texas.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/1063/supplemental/2009_USACE_JALBTCX_South_Texas_Coast_Lidar.kmz

Any conclusions drawn from the analysis of this information are not the responsibility of USACE, JALBTCX, the Office for Coastal Management, or its

partners.

Unclassified

Unclassified

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer;

None

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.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.3000

The West Texas Aerial Survey 2009 project was collected under the guidance of a Professional Mapper/Surveyor. The data were collected at a

density sufficient to support a maximum final post spacing of 1.5 points per meter.

All ground control processing and adjustment is performed using published coordinate horizontal and vertical datums (e.g. NGS CORS).

For deliverables, Corpscon for Windows Version 5.11.08 (geoid 03) was used for horizontal and vertical datum conversion as well as for

coordinate system conversion purposes (e.g. UTM to State Plane).

; Quantitative Value: 0.5 meters, Test that produced the value: Not provided

The accuracy assessment was performed using a standard method to compute the root mean square error (RMSE) based on a comparison of ground

control points (GCP) and filtered LiDAR data points. Filtered LiDAR data has had vegetation and cultural features removed and by analysis

represents bare-earth elevations. The RMSE figure was used to compute the vertical National Standard for Spatial Data Accuracy (NSSDA).

Ground control was established by 3001, Inc. A spatial proximity analysis was used to select edited LiDAR data points contiguous to the

relevant GCPs. A search radius decision rule is applied with consideration of terrain complexity, cumulative error, and adequate sample size.

Cumulative error results from the errors inherent in the various sources of horizontal measurement. These sources include the airborne GPS,

GCPs, and the uncertainty of the accuracy of the LiDAR data points. This accuracy is achieved prior to the sub-sampling that occurs through

integration with the inertial measurement unit (IMU) positions that are recorded. It is unclear at this time whether the initial accuracy

is maintained. The horizontal accuracy of the GCPs is estimated to be in the range of approximately 1 to 1.6 inches. Finally, sample size

was considered. The specification for the National Standard for Spatial Data Accuracy is a minimum of 20 points to conduct a statistically

significant accuracy evaluation (Minnesota Planning, 1999, Positional Accuracy Handbook, Minnesota Planning Land Management Information

Center, St. Paul, Minnesota., p.3). Most statistical texts indicate that a minimum of 30 sample points provide a reasonable Approximation

of a normal distribution. The intent of the NSSDA is to reflect the geographic area of interest and the distribution of error in the data

set (Federal Geographic Data Committee, 1998, Geospatial National Standard for Spatial Data Accuracy, Federal Geographic Data Committee

Secretariat, Reston, Virginia, p.3-4). Additional steps were taken to ensure the vertical accuracy of the LiDAR data including:

Step 1: Precision Bore sighting (Check Edge-matching)

Step 2: Compare the LiDAR data to the Field Survey (Field survey is to FEMA specifications and more stringent internal specifications)

Step 3: Automated Filtering

Step 4: Manual Editing (Quality Control)

; Quantitative Value: 0.15 meters, Test that produced the value: See Vertical Positional Accuracy Report

Cloud Cover: 0

The LAS files were flown at a density sufficient to support a maximum final post spacing of final post spacing of 1.5 points per meter.

The Light Detection and Ranging (LiDAR) LAS dataset is a topographic survey conducted for the West Texas Aerial Survey Project. This data was

produced for US Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX).