Data Management Plan

Territory of Guam, LiDAR Task G11PD01189

This task order is for production of surface model products of The Territory of Guam. The models are produced from data acquired using airborne Light Detection and Ranging (LiDAR) sensors. The data is calibrated, classified and processed to produce surface models and products including Classified LAS, bare earth Digital Elevation Models (DEM), intensity raster images, shapefiles of road centerlines, forest canopy, building foot prints and breaklines of surface hydrology.

Process Steps:

• 2012-03-01 00:00:00 - Ground based survey points are measured to be compared as check points with airborne data points. One hundred thirty-three survey points were collected throughout the island in various ground cover categories.
• 2013-05-01 00:00:00 - The LiDAR data was captured using a twin engine fixed wing aircraft equipped with an Optech ALTM Gemini LiDAR system. This system consists of Airborne Global Position System (ABGPS), inertial measurement unit (IMU), and laser sensor. The ABGPS collects XYZ coordinates of the laser sensor and the IMU calibrates the orientation of the aircraft. During flight, laser pulses are reflected from features on the surface and the system collects this data. The acquired LiDAR data receives a preliminary review to assure that complete coverage is obtained and to ensure the absence of data gaps. Acquisition parameters: 1. Scanner - Optech Gemini SN# 03SEN145 and 07SEN201 2. Flight Height - 450 to 600 meters above mean terrain 3. Scan Rate - 45 Hz 4. Field of View - 22 degrees 5. Pulse Rate - 70 kHz. GPS and IMU processing parameters: 1. Processing Programs and versions - Applanix - POSGPS and POSProc, versions 4.4, MMS version 5.2 2. Max separation between base stations during LiDAR collection - 0.12m 3. IMU processing monitored for consistency and smoothness - Yes GPS and IMU processing software: Optech's Dashmap version 5.20 and Applanix version 4.4,
• 2013-06-01 00:00:00 - 1. Point Cloud data is imported to TerraScan in a Microstation V8 (V) CAD environment on a specified 1500 meter by 1500 meter tiling scheme. 2. Analyze the data for overall completeness and consistency. This is to ensure that there are no voids in the data collection. 3. Inspect for calibration errors in the dataset using the TerraMatch software. This is accomplished by sampling the data collected across all flight lines and classify the individual lines to ground. The software will use the ground-classified lines to compute corrections (Heading, Pitch, Roll, and Scale). 4. Orientation corrections (i.e. Calibration corrections) are applied (if needed) to the entire dataset. 5. Automatic surface classification is performed using algorithms with customized parameters to best fit the project area. Several areas of varying relief and planimetric features were inspected to verify the final ground surface. 6. AeroMetric used ground survey points in 'open terrain' land cover to verify accurate position of the LiDAR data and ground surface. TerraScan's Output Control Report (OCR) was used to compare the survey data to the LiDAR data. This routine searches the LiDAR dataset by X and Y coordinate, finds the closest LiDAR point and compares the vertical (Z) values to the known data collected in the field. Based on the QA/QC data, a bias adjustment was determined, and the results were applied (if necessary) to the LiDAR data. 7. Each tile is reviewed for accuracy and consistency of the macro ground classification. 8. Once the automatic processing and the testing of LiDAR is complete, AeroMetric reviews the generated bare-earth surface data to ensure that proper classification was achieved as part of a Quality Control process. Point classification follows the standard established by The American Society for Photogrammetry and Remote Sensing (ASPRS) for LAS data: Code 1 Processed, but unclassified Code 2 Bare Earth / Ground Code 3 Low Vegetation Code 4 Medium Vegetation Code 5 High Vegetation Code 6 Building Code 7 Noise (Low or High, Manually identified, if needed) Code 9 Water Code 10 Ignored Ground (Breakline proximity) 9. Classified LAS data is delivered on a per tile base and named according to the Tile Layout, based on coordinates at lower left corner of the tile.
• 2015-07-10 00:00:00 - The NOAA Office for Coastal Management (OCM) received the topographic files in classified LAZ format from USGS' ftp site. The data were received in UTM Zone 55N NAD83 coordinates (meters) and vertically referenced to Guam Vertical datum in meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. LAS files were compressed to LAZ format with LASTools. 2. LAS files were removed of any duplicated points and extraneous points were reclassified to noise. 3. The LAS files were transformed to geographic (decimal degrees), ellipsoidal coordinates (meters).
• 2018-10-04 12:00:00 - The data from the previous step was in WGS84 horizontally, but on the NAD83(MA11) ellipsoid vertically and erroneously tagged as NAD83 horizontally. The data was adjusted horizontally to NAD83(MA11) by applying a Helmert transform under the assumption that the WGS84 realization was equivalent to IGS08. No explicit documentation was found for which realization of WGS84 was used and IGS08 was the most logical for data collected in 2012. Transform parameters were those found at https://www.ngs.noaa.gov/CORS/coords.shtml#Col2Exp.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4939;