2015 USGS Lidar DEM: South Terrebonne and Gulf Islands, LA

This data set is the digital elevation model (DEM) data derived from lidar which encompasses a 100 meter buffer around the south Terrebonne basin in Louisiana and the gulf coast islands of Cat Island, West Ship Island, East Ship Island, Horn Island, Petit Bois Island, Dauphin Island, Pelican Island, and the Chandeleur Islands, covering approximately 2093 square miles.

Original Dataset Description: This data set is consisting of LiDAR Point Cloud, Classified LiDAR, Digital Elevation Model, Digital Surface Model, and LiDAR Intensity Images which all pieces encompasses a 100 meter buffer around Terrebonne, LA area, approximately 2093 square miles.

Original Data Collection Ground Conditions: water at normal levels; no unusual inundation; no snow; leaf off

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the GeoTIFF files hosted by USGS on Amazon Web Services.

The USGS/NGTOC contracted Digital Aerial Solutions, LLC to obtain professional services related to the development of Light Detection and Ranging (LiDAR) data between January and February of 2015. These LiDAR elevation data will be used for conservation planning, design, research, floodplain mapping, wetlands identification, dam safety assessments, hydrologic modeling, and subsidence monitoring.

All Lidar data and associated products were acquired, calibrated, and used in the creation of Lidar derived products by Digital Aerial Solutions, LLC.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.0

",

"ldrsens" : "Leica ALS70-HP

",

"ldrmaxnr" : "Unlimited

",

"ldrnps" : "0.5

",

"ldrdens" : "4.0

",

"ldranps" : "0.3965

",

"ldradens" : "6.36

",

"ldrfltht" : "2000

",

"ldrfltsp" : "125

",

"ldrscana" : "40

",

"ldrscanr" : "34.5

",

"ldrpulsr" : "265.6

",

"ldrpulsd" : "4

",

"ldrpulsw" : "0.46

",

"ldrwavel" : "1064

",

"ldrmpia" : "1

",

"ldrbmdiv" : "0.15

",

"ldrswatw" : "1657

",

"ldrswato" : "20

",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B

"

},

"ldraccur" : {

"ldrchacc" : "0.196

",

"rawnva" : "0.154

",

"rawnvan" : "120

",

"clsnva" : "0.151

",

"clsnvan" : "120

",

"clsvva" : "0.151

",

"clsvvan" : "100

"

},

"lasinfo" : {

"lasver" : "1.4

",

"lasprf" : "6

",

"laswheld" : "Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

",

"lasolap" : Swath points were identified in these files using the standard LAS overlap bit.

",

"lasintr" : "16

",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Undetermined/Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

}

}}

Digital Elevation Model Tiles for Terrebonne, LA - QL2

The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

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.

CloudPro 1.2.0 Build 85620; GeoCue Version 2014.1.21.2; Windows 7 Operating System

\\lidarsrv\GC_Warehouse_5\80658\30\*.las

184 GB

Horizontal error in lidar derived elevation data is largely a function of positional error as derived from the Global Navigation Satellite System (GNSS), attitude (angular orientation) error (as derived from the INS) and flying altitude; and can be estimated based on these parameters. As described in Section 7.5 of the ASPRS Positional Accuracy Standards for Digital Geospatial Data the horizontal errors in lidar data are largely a function of GNSS positional error, INS angular error, and flying altitude. Therefore lidar data collected with GNSS error of 0.05m and the IMU error of 0.03492 degrees at an altitude of 1,600 meters; the expected radial horizontal positional error will be RMSEr = 11.2 cm.

Vertical Accuracy of the bare-earth LiDAR data was assessed and reported in accordance with the ASPRS Positional Accuracy Standards for Digital Geospatial Data; One hundred and sixty-one (161) surveyed points were measured for the purpose of assessing the accuracy of the Terrebonne Lidar data (41 FVA + 120 SVA). Both data sets, Lidar and Digital Elevation Models (DEMs) have been tested for their individual vertical accuracy levels. The Lidar was tested by using interpolation while the DEMs where tested by extracting the elevation of a pixel containing the checkpoint. All DEM Vertical accuracy results are reported in the DEM Metadata reports while this project wide Metadata file is reporting the vertical accuracy results from the source Lidar. The Required Consolidated Vertical Accuracy (CVA): 36.3 cm. The Required Supplemental Vertical Accuracy (SVA): 36.3 cm. The Required Fundamental Vertical Accuracy (FVA): 18.13 cm

Absolute vertical accuracy assessments for the point cloud data are made against ground check point data. For the G15PD00057, South Terrebonne and Gulf Islands QL2 LiDAR, ground check point data consisted of the ground GPS base station, and real-time kinematic (RTK) GPS techniques. Check point locations were collected at 1 – second intervals during the RTK survey. Points collected during the static pre-initialization and post-initialization were removed from the assessment so as not to bias the assessment. Local TIN models of the elevation points are built around each ground check points. The tin model elevation is sampled at the horizontal position of the ground check point. The TIN model elevation and ground check point survey elevation values were used to calculate the fundamental vertical accuracy (FVA) of the swath point clouds. The FVA of the TIN tested RMSEz 0.078 meters and 0.152 meters at the 95% confidence level in open terrain. FVA of the DEM tested at an RMSEz of 0.078 meters and 0.154 meters at the 95% confidence level in open terrain.

The raw LAS data files included all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Fundamental Vertical Accuracy specifications. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header.

Digital Elevation Model (DEM) data covers the entire 2093 square mile Area of Interest intended for this project task. All DEM tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique "NODATA" value. This value is identified in the appropriate location within the file header. Data cover the entire area specified for this project.

Data is backed up to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS GeoTIFF files that are hosted on Amazon Web Services (AWS), into the Digital Coast Data Access Viewer (DAV). The DAV accesses the raster data as it resides on AWS.