2010 USGS Lidar: Oconto County, WI

Create custom data files by choosing data area, product type, map projection, file format, datum, etc. A new metadata will be produced to reflect your request using this record as a base. Change to an orthometric vertical datum is one of the many options.

Bulk download of data files in LAZ format, geographic coordinates, orthometric heights. Note that the vertical datum (hence elevations) of the files here are different than described in this document. They will be in an orthometric datum.

This graphic displays the footprint for this lidar data set.

Link to data set report.

Link to data set report.

Link to data set breaklines.

The LiDAR data for this project was collected with Aerometric’s Optech Gemini Airborne LiDAR system (Serial Number 07SEN201). All flight planning and acquisition was completed using Optech’s ALTM-Nav, version 2.1.25b (flight planning and LiDAR control software).

The following are the acquisition settings

• Flying Height (Above Ground): 1700 meters

• Laser Pulse Rate: 70 kHz

• Mirror Scan Frequency: 32 Hz

• Scan Angle (+/-): 20

• Side Lap: 50 %

• Ground Speed: 160 kts

• Nominal Point Spacing: 1.2 meters

One (1) flight mission was required to cover the project areas. The mission was flown using the above planned values. Section 7 of the report for the flight log. Airborne GPS and IMU trajectories for the LiDAR sensor were also acquired during the time of flight. The mission was about four hours long. Before take-off, the LiDAR system and the Airborne GPS and IMU systems were initiated for a period of five minutes and then again after landing for another five minutes. The mission acquired data according to the planned flight lines.

Point Cloud Processing:

The ABGPS/IMU post processed data along with the LiDAR raw measurements were processed using Optech Incorporated’s ASDA software. This software was used to match the raw LiDAR measurements with the computed ABGPS/IMU positions and attitudes of the LiDAR sensor. The result was a “point cloud” of LiDAR measured points referenced to the ground control system.

LIDAR Processing:

The LAS files were then imported, verified, and parsed into manageable, tiled grids using GeoCue version 6.1.21.0. GeoCue allows for ease of data management and process tracking. The first step after the data has been processed and calibrated is to perform a relative accuracy assessment on the flightline to flightline comparisons.

Once the accuracy between swaths is accepted an automated classification algorithm is performed using TerraScan. This will produce the majority of the bare-earth datasets. The remainder of the data was classified using manual classification techniques. The majority of the manual edit removed points misclassified as ground (class 2) to unclassified (class 1). Erroneous low points, high points, including clouds are classified to class 7.

The NOAA Office for Coastal Management (OCM) downloaded 65 laz files from ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/ARRA-WI_OcontoCo_2010

The files contained elevation and intensity measurements for the Oconto County, WI project area. The data were in WI County Reference System, Oconto County, NAD83 HARN, US survey feet coordinates and NAVD88 (Geoid09) elevations in feet. The data were classified as: 1 - Unclassified, 2 - Ground, 7 - Noise, 8 - Model Key Points, 9 - Water, 10 - Ignored Ground. The NOAA Office for Coastal Management processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7, 8, 9, 10.

OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:

1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges.

2. The LAStools script las2las was run on the data to convert the times from gps week to adjusted gps time.

3. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 09 model, to convert from WI County Reference System, Oconto County, NAD83 HARN, US survey feet coordinates to geographic coordinates, to convert from elevations in feet to meters, to assign the geokeys, to sort the data by gps time and zip the data to database and to http.