2007 Oregon Parks and Recreation Department Silver Falls State Park Lidar

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Date that the source FGDC record was last modified.

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

Partial upload of Positional Accuracy fields only.

Partial upload to move data access links to Distribution Info.

Acquisition.

The LiDAR data was collected during March 2007. This was a leaf-off condition. An Optech 3100 LiDAR system was mounted in a

fixed-wing aircraft and flown 900 meters above ground level (AGL). A pulse repetition frequency (PRF) of 71 kHz with at

least 100% overlap (minimum 50% side-lap) was used. Greater than 8 points per square meter and near nadir scan angles were

used to increase penetration of vegetation to ground surfaces. Ground level GPS and aircraft IMU were collected during the flight.

Processing.

1. Flight lines and data were reviewed to ensure complete coverage of the study area and positional accuracy of the laser points.

2. Laser point return coordinates were computed using the REALM survey suite and PosPac based on independent data from the

LiDAR system, IMU, and aircraft.

3. The raw LiDAR file was assembled into flight lines per return with each point having an associated x, y, and z coordinate.

4. Visual inspection of swath to swath laser point consistencies within the study area were used to perform manual refinements

of system alignment.

5. Custom algorithms were designed to evaluate points between adjacent flight lines. Automated system alignment was computed

based upon randomly selected swath to swath accuracy measurements that consider elevation, slope, and intensities.

Specifically, refinement in the combination of system pitch, roll and yaw offset parameters optimize internal consistency.

6. Noise (e.g., pits and birds) was filtered using REALM software tools based on known elevation ranges and included the removal

of any cycle slips.

7. Using TerraScan and Microstation, ground classifications utilized custom settings appropriate to the study area.

8. The corrected and filtered return points were compared to the RTK ground survey points collected to verify the vertical

and horizontal accuracies.

9. Points were broken into processing bins and output areas and output as laser points, TINed and GRIDed surfaces. Bare earth

DEMs meet PSLC specifications.

The NOAA Office for Coastal Management (OCM) received the files in las format. The files contained Lidar

elevation and intensity measurements. The data was in Lambert Conformal Conic projection and NAVD88 Geoid 03 vertical datum. OCM

performed the following processing to the data to make it available within Digital Coast:

1. The data were converted from Lambert Conformal Conic coordinates to geographic coordinates.

2. The data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid 03.

3. The LAS data were sorted by latitude and the headers were updated.