Data Management Plan (Deprecated)

TASK NAME:(NRCS) Saginaw Bay, MI LiDAR

LiDAR Data Acquisition and Processing Production Task

USGS Contract No. G10PC00057

Task Order No. G11PD01254

Woolpert Order No. 071804

CONTRACTOR: Woolpert, Inc.

LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies. The LiDAR systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. The final products include first, last, and at least one intermediate return LAS, full classified LAS and one (1) meter pixel raster DEMs of the bare-earth surface in ERDAS IMG Format. The LiDAR data was acquired on November 18, 2011, November 21, 2011, November 22, 2011, November 23, 2011, December 26, 2011, April 4, 2012, April 5, 2012, and April 6, 2012.

Process Steps:

• 2011-11-18 00:00:00 - Using Leica ALS50, ALS60 and ALS70 (LiDAR) systems , 200 flight lines of high density data, at a nominal pulse spacing (NPS) of 0.7 meter, were collected for the SAGINAW BAY, MI (approximately 1631 square miles). Data Acquisition Height = 6,500 feet AGL - Aircraft Speed = 130 Knots. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of thirteen (13) missions were flown during a period of November 18 , 2011 through April 06, 2012. A single airborne global positioning system (GPS) base station was used in support of the LiDAR data acquisition. 40 ground control points were surveyed through static methods. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid09. Data for the task order is referenced to the UTM Zone 17N, North American Datum of 1983 (NAD83), and NAVD88, in Meters. Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). 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. In addition to the LAS deliverables, one layer of coverage was delivered in the IMG Format: bare-earth.
• The ALS50, ALS60 and ALS70 calibration and system performance is verified on a periodic basis using Woolpert's 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.
• 2011-11-19 00:00:00 - 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.
• 2012-05-01 00:00:00 - The individual flight lines were inspected to ensure the systematic and residual errors have been identified and removed. Then, the flight lines were compared to adjacent flight lines for any mismatches to obtain a homogenous coverage throughout the project area. The point cloud underwent a classification process to determine bare-earth points and non-ground points utilizing "first and only" as well as "last of many" LiDAR returns. This process determined bare-earth points (Class 2), High Vegetation (Class 5), Building (Class 6), Noise (Class 7), Water (Class 9) Ignored ground (Class 10), Overlap Default (Class 17), and Overlap Ground (Class 18)and unclassified data (Class 1). The bare-earth (Class 2 - Ground) LiDAR points underwent a manual QA/QC step to verify that artifacts have been removed from the bare-earth surface. The surveyed ground control points are used to perform the accuracy checks and statistical analysis of the LiDAR dataset.
• 2015-01-15 00:00:00 - The NOAA Office for Coastal Management (OCM) received the files in laz format from USGS via an FTP online repository. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 17, NAVD88 (orthometric) heights in meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The data were converted from UTM coordinates to geographic coordinates. 2. The data were converted from NAVD88 (orthometric) heights in meters to GRS80 (ellipsoid) heights in meters using Geoid 09. 3. The LAS data were sorted by latitude and the headers were updated. 4. Erroneous elevations were removed.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4807

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