Data Management Plan (Deprecated)

The project vendor, Woolpert, Inc., acquired highly accurate Light Detection and Ranging (lidar) elevation data for the Central Lakes area of Minnesota in Spring 2012. The data cover Aitkin, Cass, Hubbard, Itasca, Todd and Wadena counties, along with a portion of Koochiching County. Lidar data are in the UTM Zone 15 coordinate system, NAD83 96, NAVD88 Geoid09, meters. The tiling scheme is 16th USGS 1:24,000 quadrangle tiles.

The vendor delivered the data to the Minnesota Department of Natural Resources (DNR) in several formats:

1) One-meter digital elevation model

2) Edge-of-water breaklines

3) Classified LAS formatted point cloud data

DNR then quality checked the data and created two additional products: two-foot contours and building outlines.

The original metadata record was created at the Minnesota Geospatial Information Office using information supplied by Woolpert and DNR.

This metadata supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the Entwine Point Tiles (EPT) hosted by USGS on Amazon Web Services.

Lineage Statement:
The Central Lakes, MN lidar was ingested into the Data Access Viewer for custom product generation by leveraging USGS hosted Entwine Point Tiles.

Process Steps:

• Vendor Processing Steps: Using Light Detection And Ranging (lidar) systems, 442 flight lines of high density data, at a nominal pulse spacing (NPS) of 1.5 meter, were collected over Minnesota counties of Aitkin, Cass, Hubbard, Itasca, Todd, Wadena and a portion of Koochiching (approximately 11,690 sq. miles), along with a 100 meter buffer beyond the project tile boundary. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of thirty one (31) missions were flown from April 05, 2012 through April 28, 2012. A minimum of six (6) airborne global positioning system (GPS) base stations were used in support of the lidar data acquisition. All data for this task order is referenced to UTM 15N, NAD83, 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 ArcGrid binary format: bare-earth. System Parameters for 1.5 NPs: ALS60 Specifications Post Spacing (Minimum): 4.92 ft / 1.5 m AGL (Above Ground Level) average flying height: 7,800 ft / 2,377.4 m MSL (Mean Sea Level) average flying height: 9,000 ft / 2712.7 m Average Ground Speed: 150 knots / 172.6 mph Field of View (full): 40 degrees Pulse Rate: 99 kHz Scan Rate: 38 Hz Side Lap (Minimum): 25% ALS70 Specifications Post Spacing (Minimum): 4.92 ft / 1.5 m AGL (Above Ground Level) average flying height: 7,800 ft / 2,377.4 m MSL (Mean Sea Level) average flying height: 9,075 ft / 2766 m Average Ground Speed: 150 knots / 172.6 mph Field of View (full): 40 degrees Pulse Rate: 115.3 kHz Scan Rate: 25.1 Hz Side Lap (Minimum): 25% Optech ALTM Gemini Specifications Post Spacing (Minimum): 4.92 ft / 1.5 m AGL (Above Ground Level) average flying height: 6,800 ft / 2,072.6 m MSL (Mean Sea Level) average flying height: 9,000 ft / 2712.7 m Average Ground Speed: 150 knots / 172.6 mph Field of View (full): 40 degrees Pulse Rate: 99.1 kHz Scan Rate: 38 Hz Side Lap (Minimum): 25% The ALS60, ALS70 and Optech Gemini 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. 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 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 The LiDAR LAS files for this task order have been classified into the Default (Class 1), Ground (Class 2), Low Vegetation (Class 3 (less than 1.1 m)), Medium Vegetation (Class 4 (1.11 - 2.4 m)), High Vegetation (Class 5 (2.41 - 200 m)) Buildings (Class 6), Noise (Class 7), Model Keypoints (Class 8), Water (Class 9), Ignored Ground (Class 10), bridges (Class 14), and Overlap (Class 17) classifications. 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.
• Additional Products Generated by Minnesota DNR staff: These products are in the geodatabase for each of the tiles: 1. Two-foot contours were created by resampling the 1-meter DEM to 3 meters, then smoothing the 3-meter grid using a neighborhood average routine, and then creating contours from this surface using standard ArcGIS processing tools. 2. Building outlines were created by extracting from the LAS files those points with Classification 6 (buildings), then grouping those points within 3 meters of each other into a single cluster and then creating an outline around those points. This was done using standard ArcMap tools. 3. Hillshades were created from the one- and three-meter DEMs using standard ArcMap tools. Azimuth value = 215, Altitude = 45, Z-Factor = 1
• Original point clouds in LAS/LAZ format were restructured as Entwine Point Tiles and stored on Amazon Web Services. The data were reprojected horizontally to WGS84 web mercator (EPSG 3857) and no changes were made to the vertical (NAVD88 GEOID09 meters).
• 2022-12-05 00:00:00 - The NOAA Office for Coastal Management (OCM) created references to the Entwine Point Tiles (EPT) that were ingested into the NOAA Digital Coast Data Access Viewer (DAV). No changes were made to the data. The DAV will access the point cloud as it resides on Amazon Web Services (AWS) under the usgs-lidar-public container. These are the AWS URLs being accessed: https://s3-us-west-2.amazonaws.com/usgs-lidar-public/USGS_LPC_MN_CentralLakes_B1_2012_LAS_2016/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/USGS_LPC_MN_CentralLakes_B2_2012_LAS_2016/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/USGS_LPC_MN_CentralLakes_B3_2012_LAS_2016/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/USGS_LPC_MN_CentralLakes_B4_2012_LAS_2016/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/USGS_LPC_MN_CentralLakes_B5_2012_LAS_2016/ept.json

Data is available online for bulk and custom downloads.

Data is backed up to tape and to cloud storage.