Data Management Plan (Deprecated)

Product: Classified LAS, was filtered and manually edited to achieve a clean Bare Earth surface. This Classified LAS v1.4 data set was used to create; hydro-flattened breaklines, hydro-flattened Bare Earth DEMs, Digital Surface Models, and Intensity Images.

Geographic Extent: AOI was located along an area of coastal Louisiana referred to as Chenier Plain, which includes portions of Calcasieu, Cameron, Vermillion, Iberia, and St. Mary Parishes. The area of interest covered approximately 2942 square miles. Dataset Description: LA Chenier Plain Lidar 2017 B16 project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.70 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Lidar Base Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011), UTM Zone 15N, Meter and vertical datum of NAVD88 (GEOID12B), Meter. Lidar data was delivered as: flightline-extent raw LAS v1.4 swaths, classified point cloud LAS v1.4 files formatted to 3817 individual 1,500 m x 1,500 m tiles in NAD83 (2011), UTM Zone 15N, Meter. Derivatives were produced as tiled; Bare Earth Surface DEMs, Digital Surface Models, Intensity Images; all tiled to the same 1,500 m x 1,500 m schema.

Ground conditions: Lidar was collected in Winter of 2017 by Aerial Services, Inc. (ASI), and WOOLPERT. The Chenier Plain Wetland areas contain hundreds of impoundments related to aquaculture operations. These fields are flooded and contained within the impoundments on a semi-permanent basis, including during the Chenier Plain lidar acquisition timeframe. This is an understood and accepted acquisition condition. Furthermore, impoundments equal to or greater than 2 acres are treated as hydrologically flattened features within the data deliverables. Tidal Restriction: The following tide gauges were considered suitable for prediction of regional water levels within the AOI; Sabin Pass North, TX NOS (8770570), Calcasieu Pass, LA NOS (8768094), Freshwater Canal Locks, LA NOS (8766072), and Amerada Pass, LA NOS (8764227). Water levels at flight time shall were below -0.10 meters (mean seal level) for the Calcasieu Pass, LA tide gauge (8768094) in the west and -0.10 meters (mean seal level) for the Amerada Pass, LA tide gauge (8764227). Meteorological: Acquisition did not occur after passage of a moderate to strong high-pressure system generating northerly winds in excess of five (5) knots. In addition, it is noted switching of winds from WNW to ENE is a tipping point for switching from wind driven marsh drainage to marsh flooding. Ground Conditions: Within the extreme eastern AOI (swamp and fresh to intermediate marsh occurring northeast of Marsh Island and bordering East Cote Blanche Bay) Lidar was not acquired when the Lower Atchafalaya River stage was less than 4 feet as determined by the latest measurements taken at gauge (USGS 07381605) at Morgan City.

Lidar was not acquired when regional precipitation driven flooding occurred in local rivers with significant impact to wetland impoundments located throughout the entire Chenier Plain west of Cote Blanch Bay. The following local rivers shall be monitored for flood conditions; Vermillion, Mermentau, Calcasieu, and Sabine rivers. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Woolpert established a total of 68 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. Additional independent accuracy checkpoints were collected (94 NVA points and 75 VVA points) and 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 3817 LA_ChenierPlain_2017 laz files from this USGS site: ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_LA_Chenier_Plain_2017_LAS_2018/ and processed the data to the Data Access Viewer (DAV) and https.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Hydro breaklines are also available. These data are available for download at the link provided in the URL section of this metadata record. Please note that these products have 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.

Process Steps:

• 2017-01-08 00:00:00 - Using the Leica Lidar sensors, high density data, at a nominal pulse spacing (NPS) of 0.7 meters, were collected for this task order. Specific information regarding latitude, longitude, and ellipsoid height to the L1 phase center is included in the lidar processing report. LA Chenier Plain Lidar 2017 B16 Lidar task order was processed and delivered in NAD 1983(2011) UTM Zone 15N, NAVD88 Meter. The geoid used to reduce satellite derived elevations to orthometric heights was GEOID12B. Once the data acquisition and GPS processing phases are complete, the lidar data was processed immediately to verify the coverage had no voids. The GPS and IMU data was post processed using differential and Kalman filter algorithms to derive a best estimate of trajectory. The quality of the solution was verified to be consistent with the accuracy requirements of the project. The SBET was used to reduce the lidar slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. The ALS calibration and system performance is verified on a periodic basis using the calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of lidar data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw lidar data is reduced using the refined misalignment angles.
• 2017-01-08 00:00:00 - Classification Filters were applied to aid in the definition of terrain characteristics and to maintain ground. Filtering processes address aspects of the data such as; ground points, noise points, air points, low points, manmade features, vegetation, and overlap points. The Bare Earth surface was manually reviewed to ensure correct classification of Class 2 (Ground). Upon completion of bare earth review hydro-breaklines were generated through heads-up digitization. Ground (Class 2) Lidar points inside Inland Ponds and Lakes, and Inland Streams and Rivers were classified to Water (Class 9). A buffer of 2.3 feet was used around each hydro-flattened feature to classify Ground points (Class 2) to Ignored ground (Class 10). Island features were checked to ensure that Ground point (Class 2) remained classified as Ground. Ground points (Class 2) within 2.3 feet of breaklines, used to reduce triangulation between bridge decks were also classified to Ignored ground (Class 10). All bridge decks were classified to Bridge (Class 17). All remaining Points were filtered , or manually classified to their respective Point Classification; Processed (Class 1), Vegetation (Class 3), Low Noise (Class 7), High Noise (Class 18) Overlap data was identified using the Overlap Flag, LAS 1.4 specifications. All data was manually reviewed and any remaining artifacts removed. The bare-earth (Class 2 - Ground) lidar points underwent a manual QA/QC step to verify the quality of the DEM as well as a peer-based QC review. This included a review of the DEM surface to remove artifacts and ensure topographic quality. Classification of water (class 9) and ignored ground (class 10) was completed via the use of the hydrologic breaklines collected for the hydro-flattening phase. Buildings (Class 6) was achieved via the used of digitized building footprints. The overlap classes were determined by first identifying the overlapping areas and reclassifying the LAS data by offset from a corridor. This allows the returns located on the edge of the swath to be removed from the bare earth coverage in an effort to produce a more uniform data density. The returns determined to be overlap including overlap default, ground, water, and ignored ground are then applied an overlap flag and reclassified to their respective standard classification value. The surveyed ground control points are used to make vertical adjustments to the data set and to perform the accuracy checks and statistical analysis of the lidar dataset. Supervisory QC monitoring of work in progress and completed editing ensured consistency of classification character and adherence to project requirements across the entire project area. The resulting deliverables for this task order consist of classified LAS file in LAS 1.4 format, Raw Swath LAS files in LAS 1.4 format,DEM and DSM files in Tiff format, 8-bit gray scale Intensity files in GeoTIFF format, Hydrologic and Bridge abutment breakline data in ESRI geodatabase format.
• The NOAA Office for Coastal Management (OCM) downloaded 3817 LA_Chenier_Plain_2017 laz files from this USGS site: ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_LA_Chenier_Plain_2017_LAS_2018/. The data were in UTM Zone 15 North coordinates and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 - Unclassified, 2 - Ground, 3 - Low vegetation (less than or equal to 3 meters), 7 - Low Noise, 9 - Water, 10 - Ignored Ground, 17 - Bridge Decks, 18 - High Noise. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 3, 7, 9, 10, 17, 18. 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 laz files to check for errors. 2. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 3. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 12B model, to convert from NAD83 2011 UTM Zone 15 North coordinates in meters to geographic coordinates, to assign the geokeys, to sort the data by gps time and zip the data to database and to http.

Data is available online for bulk and custom downloads.