2010 US B.O.R. Lidar DEM: Klamath River, CA

Acquisition dates.

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This graphic displays the footprint for this lidar data set.

Link to data set report.

Acquisition.

The LiDAR survey uses a Leica ALS60 laser system mounted on a Cessna Caravan. For the Klamath River survey area, the sensor scan angle was ±13 degrees from nadir1 with a pulse rate designed to yield an average native density (number of pulses emitted by the laser system) of > 8 points per square meter over terrestrial surfaces. All survey areas were surveyed with an opposing flight line side-lap of

>50% (>100% overlap). The Leica ALS60 system allows up to four range measurements (returns) per pulse, and all discernible laser returns were processed for the output dataset. It is not uncommon for some types of surfaces (e.g. dense vegetation or water) to return fewer pulses than the laser originally emitted. These discrepancies between 'native' and 'delivered' density will vary depending on terrain, land cover and the prevalence of water bodies.

LiDAR survey datasets were referenced to the 1 Hz static ground GPS data collected over pre- surveyed monuments with known coordinates. While surveying, the aircraft collected 2 Hz kinematic GPS data, and the onboard inertial measurement unit (IMU) collected 200 Hz aircraft attitude data. Waypoint GPS v.8.10 was used to process the kinematic corrections for the aircraft. The static and kinematic GPS data were then post-processed after the survey to obtain an accurate GPS solution and aircraft positions. IPAS v.1.35 was used to develop a trajectory file that includes corrected aircraft position and attitude information. The trajectory data for the entire flight survey session were incorporated into a final smoothed best estimated trajectory (SBET) file that contains accurate and continuous aircraft positions and attitudes.

Laser point coordinates were computed using the IPAS and ALS Post Processor software suites based on independent data from the LiDAR system (pulse time, scan angle), and aircraft trajectory data (SBET). Laser point returns (first through fourth) were assigned an associated (x, y, z) coordinate along with unique intensity values (0-255). The data were output into large LAS v. 1.2 files; each point maintains the corresponding scan angle, return number (echo), intensity, and x, y, z (easting, northing, and elevation) information.

The following processing steps were performed on the data:

• LiDAR points were then filtered for noise, pits (artificial low points) and birds (true birds as well as erroneously high points) by screening for absolute elevation limits, isolated points and height above ground.

• Points from overlapping lines were tested for internal consistency and final adjustments were made for system misalignments (i.e., pitch, roll, heading offsets and scale).

• The TerraScan software suite was used for classifying near-ground points (Soininen, 2004). The resulting ground classified points were visually inspected and additional ground point modeling was performed in site-specific areas to improve ground detail.

Data was obtained by NOAA Office for Coastal Management from DOGAMI. Data were in California State Plane Zone 1 NAD83(HARN) US survey feet with NAVD88 (Geoid09) US Survey feet vertically. Data were converted to geographic coordinates in ellipsoid heights (meters) using the general cartographic transform package subroutines and reversing the application of GEOID09.