Data Management Plan (Deprecated)

Light Detection and Ranging (LiDAR) data is remotely sensed high-resolution elevation data collected by an airborne collection platform. This LiDAR dataset is a survey of American Samoa including the islands of Tutuila, Aunu'u, Ofu, Olosega, Ta'u and Rose Atoll.

The project area consists of approximately 75 square miles. The project design of the LiDAR data acquisition was developed to support a nominal post spacing of 1.0 meter or better (1.0 meter GSD). GMR Aerial Surveys Inc. d/b/a Photo Science, Inc. acquired 108 flight lines in 7 lifts between June 2012 and July 2012. This collection was for NOAA Office for Coastal Management (OCM).

The data collection was performed with a Beechcraft King Air 90 twin engine aircraft (tail number N87E) utilizing an Optech Gemini sensor; collecting multiple return x, y, and z as well as intensity data. The data were provided to OCM, classified as:

Unclassified (1), Ground (2), Low Point (Noise) (7), Water (9), Breakline Edge (10), Overlap Unclassified (17) and Overlap Ground (18).

The classifications available for download from the Digital Coast are:

Unclassified (1), Ground (2), Low Point (Noise) 7, Water (9), Removed Ground (breakline edge) (10), and Overlap (12).

The collection conditions were cloud and fog-free between the aircraft and the ground; streams must be within their banks; and low tide acquisition if at all possible.

Data voids within a single swath were avoided whenever possible. Acceptable void areas are caused by a water body; areas of low near infrared (NIR) reflectivity such as asphalt or composition roofing and where appropriately filled in by another swath. Unfortunately, during the LiDAR acquisition there were a few mountain peaks where the clouds never lifted high enough to collect LiDAR.

In order to post process the LiDAR data to meet task order specifications, Photo Science, Inc. established control points that were used to calibrate the LiDAR to known ground locations established on Tutuila. Please see the survey report for more details on ground control point collection at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12a/2490/supplemental/PhotoScience-AmSam_PostFlightAcquisitionReport_FINAL.pdf

The dataset was developed based on a horizontal projection/datum of UTM NAD83 (PACP00), UTM Zone 2, meters. The vertical datum used during the collection, varied by island. NAVD88 (ASVD02), meters was used for the island of Tutuila (and Aunu'u). NAVD1988 (GEOID09), meters was used for the islands of Ofu, Olosega and Tau. Rose atoll was adjusted from Ellipsoid heights to a mean low water (MLW) datum. Upon receipt of the data, the NOAA Office for Coastal Management converted the lidar data to geographic coordinates and ellipsoid heights using GEOID09. Rose Atoll data were converted to geographic coordinates and to ellipsoid heights using the MLW correction value of 22.8 m. Conversion is for data storage and Digital Coast provisioning purposes. LiDAR data was collected in RAW flightline swath format and processed to create Classified LAS 1.2 files.

Process Steps:

• 2012-01-01 00:00:00 - Control Process: Photo Science, Inc. established control points on Tutuila that were used to calibrate the LiDAR to known ground locations to be used in the post processing of the LiDAR data. The points were located on relatively flat terrain on surfaces that generally consisted of grass, gravel, pavement or bare earth and were in well-defined discrete locations. See The Post Flight Aerial Acquisition and Calibration Report for additional collection parameters and methodologies: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12a/2490/supplemental/PhotoScience-AmSam_PostFlightAcquisitionReport_FINAL.pdf Raw Flight Line Process: Applanix software was used in the post processing of the airborne GPS and inertial data that is critical to the positioning and orientation of the sensor during all flights. POSPac MMS provides the smoothed best estimate of trajectory (SBET) that is necessary for Optech's post processor to develop the point cloud from the LiDAR missions. The point cloud is the mathematical three dimensional collection of all returns from all laser pulses as determined from the aerial mission. At this point this data is ready for analysis, classification, and filtering to generate a bare earth surface model in which the above ground features are removed from the data set. The point cloud was manipulated within the Optech software; GeoCue, TerraScan, and TerraModeler software was used for the automated data classification, manual cleanup, and bare earth generation from this data. Project specific macros were used to classify the ground and to remove the side overlap between parallel flight lines. All data were manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Classified LAS Process: All ground (ASPRS Class 2) LiDAR data inside of the Lake Pond and Double Line Drain hydro flattening breaklines were then classified to water (ASPRS Class 9) using TerraScan macro functionality. A buffer of 1 meter was also used around each hydro flattened feature to classify these ground (ASPRS Class 2) points to ignored ground (ASPRS Class 10). All Lake Pond Island and Double Line Drain Island features were checked to ensure that the ground (ASPRS Class 2) were reclassified to the correct classification after the automated classification was completed. A description of each deliverable class can be found below: Class 1 - Unclassified points; includes non-ground points such as buildings and vegetation. Class 2 - Ground points Class 7 - Noise points; includes all high and low noise points that do not represent legitimate features. Class 9 - Water points Class 10 - Ignored Ground points; includes all ground points that fall within a 1 meter buffer around any hydro breakline feature. Classifying these points aids in the hydro flattened DEM creation. Class 17 - Overlap Unclassified points; Overlap points that represent non-ground features. Class 18 - Overlap Ground points; Overlap points that represent the ground surface. These points were classified based on their x,y and z proximity to the Class 2 ground points. No manual cleanup was performed on these points. All overlap data was processed through automated functionality provided by TerraScan to classify the overlapping flight line data to class. Data was then run through additional macros to ensure deliverable classification levels matching the ASPRS LAS Version 1.2 Classification structure. GeoCue functionality was then used to ensure correct LAS Versioning. In-house software was used as a final QA/QC check to provide LAS Analysis of the delivered tiles. QA/QC checks were performed on a per tile level to verify final classification metrics and full LAS header information.
• 2013-05-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received the files in las format. The files contained LiDAR elevation and intensity measurements. The data were delivered in UTM Zone 2 projection, NAD83 datum, meters. Data available are classified as follows: Unclassified (1), Ground (2), Low Point (Noise) 7, Water (9), Removed Ground (breakline edge) (10), and Overlap (12). OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The data were converted from UTM Zone 2, NAD83 coordinates to geographic coordinates. 2. The Tutuila (and Aunu'u), Ofu, Olosega, and Tau data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid09. 3. The Rose Atoll data were converted from MLW to ellipsoid (using MLW correction value of 22.8 m) 4. The data were zipped to laz format.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2490

This data set is dynamically generated based on user-specified parameters.

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