2010 USFS Lidar DEM: Malheur National Forest (LC West), OR

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Link to the data set report.

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Information on the NOAA Office for Coastal Management (OCM)

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.

Airborne Acquisition – Equipment and Methodology

LiDAR acquisition of LC West was performed with an Optech ALTM Orion sensor. Aero-Graphics flew at an average altitude of 3280 ft AGL (above ground level) and made appropriate adjustments to compensate for topographic relief. The PRF (pulse rate frequency) used for collection was 100 kHz, scan frequency of 70 Hz, and scan angle of +/- 11 degrees from the nadir position (full scan angle 22 degrees). The ALTM Orion features roll compensation that adjusts the mirror to maintain the full scan angle integrity in relation to nadir, even when less than perfect weather conditions push the sensor off nadir. Acquisition was performed with a 50% side lap and yielded >12.5 points per square meter throughout the project boundary. The Optech ALTM Orion is capable of receiving up to four range measurements, including 1st, 2nd, 3rd, and last returns for every pulse sent from the system.

The ALTM Orion is also equipped with a GPS/IMU unit that continually records the XYZ position and roll, pitch and yaw attitude of the plane throughout the flight. This information allows us to correct laser return data positions that may have been thrown off by the plane’s natural movement.

The ALTM Orion LiDAR sensor is equipped with ALTM-Nav Flight Management System Software. ALTM-Nav is not only used to guide the airborne mission in flight, but our office flight planning is performed using a combination of Nav and traditional flight planning practices. The smooth transition from flight planning to aerial operations eliminates discrepancies between the flight plan and what is actually acquired. The use of ALTM-Nav helps ensure an accurate and consistent acquisition mission with real-time quality assurance while still airborne. The system operator can monitor the point density and swath during the mission to confirm adequate coverage within the area of interest

Ground Survey – Equipment and Methodology

Aero-Graphics used survey data to differentially correct the aircraft’s trajectory data and to ensure that the LiDAR data maintained its true geographic integrity. Using our own static base stations at strategic points in the project area, with data collected during the time of the LiDAR mission, we used Multi-Base processing in Applanix’s POS GNSS software to accurately correct the aircraft’s real-time GPS trajectory.

LiDAR Processing Workflow and Software

a. Absolute Sensor Calibration. The absolute sensor calibration is defined as the difference in roll, pitch, heading, and scale between the raw laser point cloud from the sensor and surveyed control points on the ground over two separate sites. Software: Dashmap 4.1801; ACalib 1.3.5.7.

b. Kinematic Air Point Processing. Differentially corrected the 1-second airborne GPS positions with ground base stations; combined and refined the GPS positions with 1/200-second IMU (roll-pitch-yaw) data through development of a smoothed best estimate of trajectory (SBET). Software: Applanix POSPac 5.3.3664.28463.

c. Raw LiDAR Point Processing. Combined SBET with raw LiDAR range data; solved real-world position for each laser point; produced point cloud data by flight strip in ASPRS v1.1 .LAS format; output in WGS84 UTM Ellipsoid Heights. Software: LiDAR Mapping Suite 1.0.

d. Relative Calibration. Tested relative accuracy; performed relative calibration by correcting for roll, pitch, heading, and scale discrepancies between adjacent flightlines. Results presented in Section 4.1. Software: LiDAR Mapping Suite 1.0.

e. Tiling & Long/Short Filtering. Cut data into project-specified tiles and filtered out grossly long and short returns. Software: TerraScan 10.011.

f. Classification. Ran classification algorithms on points in each tile; separated into ground, unclassified, high outliers and low outliers; revisited areas not completely classified automatically and manually corrected them. Software: TerraScan 10.011.

g. Absolute Accuracy Assessment. Performed comparative tests that showed Z-differences between each static survey point and the laser point surface. Results presented in Section 4.2. Software: TerraScan 10.001.

h. Datum Transformation. Transformed all .LAS tiles from WGS84 UTM 11N Ellipsoid Heights into NAD83 UTM 11N, adjusted for orthometric heights on NAVD88 (Geoid03). Integrity of the .LAS file format was maintained throughout the process. Software: Blue Marble Desktop 2.1.

i. DEM Creation. Generated 2-meter first-return DEMs and 1-meter ground surface DEMs in ESRI Raster Grid format, tiled according to project specifications. Software: TerraScan 10.011.

j. Intensity Image Creation. Generated 1-meter pixel intensity images in GeoTIFF format, tiled according to project specifications. Software: TerraScan 10.011.

The NOAA Office for Coastal Management (OCM) received 57 raster DEM files in ESRI ArcGrid format from DOGAMI. The data were in UTM Zone 11, NAD83, meters coordinates and NAVD88 (Geoid03) elevations in meters. The bare earth raster files were at a 1 m grid spacing. No metadata record was provided for this data set. This record was created by the NOAA Office for Coastal Management (OCM) using information from the Aero-Graphics, Inc., Lidar Data Collection report.

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

1. Used internal script to assign the vertical EPSG code (5703) and convert to GeoTiff format.

2. Copied to the files to https.