2007 USFS Lidar: Malheur National Forest - Damon Creek, OR

Malheur National Forest, Damon Creek project area.

Dates of collection.

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Bulk download of lidar files in laz format, geographic coordinates, orthometric heights.

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

This graphic displays the footprint for this lidar data set.

Data report

Acquisition

The full survey was conducted September 15 and 16, 2007. The LiDAR survey utilized a Leica ALS50 Phase II laser mounted in a Cessna Caravan 208B. The sensor scan angle was ±14o from nadir1 with a pulse rate designed to yield an average native density (number of pulses emitted by the laser system) of ≥4 points per square meter over terrestrial surfaces. Some types of surfaces (e.g. dense vegetation or water) may return fewer pulses than the laser originally emitted. Therefore, the delivered density can be less than the native density and variable according to distributions of terrain, land cover and water bodies. The Leica ALS50 Phase II system allows up to four range measurements per pulse, and all discernable laser returns were processed for the output dataset.

To solve for laser point position, it is vital to have an accurate description of aircraft position and attitude. Aircraft position is described as x, y and z and measured twice per second (2 Hz) by an onboard differential GPS unit. Aircraft attitude is measured 200 times per second (200 Hz) as pitch, roll and yaw (heading) from an onboard inertial measurement unit (IMU).

Calibration/Classification

1. Resolve kinematic corrections for aircraft position data using kinematic aircraft GPS and static ground GPS data.

Software: Waypoint GPS v.7.60

2. Develop a smoothed best estimate of trajectory (SBET) file that blends post-processed aircraft position with attitude data. Sensor heading, position, and attitude are calculated throughout the survey.

Software: IPAS v.1.0

3. Calculate laser point position by associating SBET position to each laser point return time, scan angle, intensity, etc. Creates raw laser point cloud data for the entire survey in *.las (ASPRS v1.1) format.

Software: ALS Post Processing Software

4. Import raw laser points into subset bins (less than 500 MB, to accommodate file size constraints in processing software). Perform manual relative accuracy calibration and filter for pits/birds. Ground points are then classified for individual flight lines (to be used for relative accuracy testing and calibration).

Software: TerraScan v.6.009

5. Test relative accuracy using ground classified points per each flight line. Perform automated line-to-line calibrations for system attitude parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calibrations are performed on ground classified points from paired flight lines. Every flight line is used for relative accuracy calibration.

Software: TerraMatch v.6.009

6. Import position and attitude data. Classify ground and non-ground points. Assess statistical absolute accuracy via direct comparisons of ground classified points to ground RTK survey data. Convert data to orthometric elevations (NAVD88) by applying a Geoid03 correction. Create ground model as a triangulated surface and export as ArcInfo ASCII grids at the specified pixel resolution.

Software: TerraScan v.6.009, ArcMap v9.2

The NOAA Office for Coastal Management (OCM) received 246 lidar point cloud files in laz format from the USDA Forest Service. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 11 North (NAD83) coordinates and NAVD88 (Geoid03) elevations, with all units in meters.

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. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 03 model, to convert from UTM Zone 11N coordinates in meters, to geographic coordinates, to assign the geokeys, to sort the data by gps time, and zip the data to database and to http.