2018 LADOTD Lidar: Amite Watershed (LA, MS)

Product: These lidar data are processed Classified LAS 1.4 files, formatted to 2410 individual 1500 m x 1500 m tiles; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: The Amite Watershed, including East Feliciana, St. Helena, East Baton Rouge, Livingston, Iberville, and Ascension Parishes, Louisiana, and Amite, Wilkinson, Franklin, and Lincoln Counties, Mississippi, covering approximately 1,884 square miles.

Dataset Description: The Louisiana Department of Transportation and Development Amite Watershed, Lidar Project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 2410 individual 1500 m x 1500 m tiles, as tiled Intensity Imagery, and as tiled bare earth DEMs; all tiled to the same 1500 m x 1500 m schema.

Ground Conditions: Lidar was collected in early 2018, while no snow was on the ground and rivers were at slightly higher than normal levels causing flooding in areas along the Mississippi river. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Forte and Tablada established a total of 75 ground control points that were used to calibrate the lidar to known ground locations established throughout the Amite Watershed project area. An additional 125 independent accuracy checkpoints, 71 in Bare Earth and Urban landcovers (71 NVA points), 54 in Tall Grass and Brushland/Low Trees categories (54 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

The NOAA Office for Coastal Management (OCM) downloaded this data set from this USGS site:

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_LA_Amite_2018_LAS_2019

These files were processed to the Data Access Viewer (DAV) and https. The total number of laz files downloaded and processed was 2410.

The breaklines were also downloaded and are available for download at the link provided in the URL section of this metadata record. Please note that this product has not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 0.6 meter cell size. These lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Dewberry. SUBCONTRACTOR: Precision Aerial Reconnaissance (PAR) Lidar data were acquired and calibrated by Precision Aerial Reconnaissance (PAR). All follow-on processing was completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v1.2",

"ldrsens" : "Leica ALS70-HP",

"ldrmaxnr" : "7",

"ldrnps" : "0.33",

"ldrdens" : "9.18",

"ldranps" : "0.33",

"ldradens" : "9.18",

"ldrfltht" : "1152",

"ldrfltsp" : "115",

"ldrscana" : "40",

"ldrscanr" : "48.4",

"ldrpulsr" : "450",

"ldrpulsd" : "9",

"ldrpulsw" : "0.2",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1252.54",

"ldrswato" : "30",

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

},

"ldraccur" : {

"ldrchacc" : "1.0",

"rawnva" : "0.070",

"rawnvan" : "71",

"clsnva" : "0.070",

"clsnvan" : "71",

"clsvva" : ".116",

"clsvvan" : "54"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

"lasolap" : "Swath "overage" points were not identified in these files.",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "8",

"clasitem" : "Model Key Points"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Points"

}

}}

Any conclusions drawn from the analysis of this information are not the responsibility of Louisiana Dept. of Transportation & Developement, USGS, 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.

The project specifications require that only Non-Vegetated Vertical Accuracy (NVA) be computed for raw lidar point cloud swath files. The required accuracy (ACCz) is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the “bare earth” and "urban" land cover classes. The NVA was tested with 71 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

Tested 0.070 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud swath files was calculated against TINs derived from the final calibrated and controlled swath data using 71 independent checkpoints located in Bare Earth and Urban land cover classes.

These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There is a known void 274427.58 sq m (0.1 sq mi) in size in tiles 15RXP7252 and 15RXP7254. Please see the project report for more details and explanation of cause for this void. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

With the exception of the small void mentioned in the Completeness tag, data covers the entire area specified for this project.

Data is backed up to tape and to cloud storage.