2012-2013 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Hoh River Watershed, Washington (Deliveries 1 and 2)

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This graphic shows the lidar coverage for a section of Jefferson County, Washington.

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.

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Delivery 1:

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

Software: Waypoint GPS v.8.10, Trimble Business Center 2.6

2. Developed a smoothed best estimate of trajectory (SBET) file that blends post-processed aircraft position with attitude data. Sensor head position and attitude were calculated throughout the survey. The SBET data were used

extensively for laser point processing.

Software: IPAS TC v.3.1

3. Calculated laser point position by associating SBET position to each laser point return time, scan angle, intensity, etc. Created raw laser point cloud data for the entire survey in *.las (ASPRS v. 1.2) format. Data were

then converted to orthometric elevations (NAVD88) by applying a Geoid03 correction.

Software: ALS Post Processing Software v.2.74, Corpscon 6

4. Imported raw laser points into manageable blocks (less than 500 MB) to perform manual relative accuracy calibration and filter for pits/birds. Ground points were then classified for individual flight lines (to be used for

relative accuracy testing and calibration).

Software: TerraScan v.12.004

5. Using ground classified points per each flight line, the relative accuracy was tested. Automated line-to-line calibrations were then performed for system attitude parameters (pitch, roll, heading), mirror flex (scale) and

GPS/IMU drift. Calibrations were performed on ground classified points from paired flight lines. Every flight line was used for relative accuracy calibration.

Software: TerraMatch v.12.001

6. Position and attitude data were imported. Resulting data were classified as ground and non-ground points. Statistical absolute accuracy was assessed via direct comparisons of ground classified points to ground RTK survey data.

Software: TerraScan v.12.004, TerraModeler v.12.002

7. Bare Earth models were created as a triangulated surface and exported as ArcInfo ASCII grids at a 3-foot pixel resolution. Highest Hit models were created for any class at 3-foot grid spacing and exported as ArcInfo ASCII grids.

Software: TerraScan v.12.004, ArcMap v.10.0, TerraModeler v.12.002

8. Intensity images were created as Geo TIFFs and mosaicked to the final delineation.

Software: TerraScan v.12.004, ArcMap v.10.0, TerraModeler v.12.002

Delivery 2:

Acquisition. WSI collected the Hoh Watershed LiDAR data between 04/14/12 and 07/24/13. The survey used a Leica ALS60 laser system mounted in a Cessna Caravan 208B and a ALS50 laser system mounted in a Partenavia. Data was

collected using a single pulse flight plan. 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.

Leica ALS 60 Instrument Parameters (4/14/12, 4/15/12, 4/17/12, 4/19/12, 4/20/12, 4/21/12); Beam diameter: 21 cm, Pulse rate: 196-107.8 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 60 %, Laser output power: 17%

Field of view (FOV): 28 degrees, Beam wavelength: 1064 nm, Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 449 m AGL: 900 m Average pulse density: 8

Leica ALS 50 Phase II Instrument Parameters (4/15/12, 4/21/12); Beam diameter: 21 cm, Pulse rate: 96-107.8 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 60 %, Laser output power: 26% Field of view (FOV): 28 degrees,

Beam wavelength: 1064 nm, Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 449 m AGL: 900 m Average pulse density: 8

Leica ALS 50 Phase II Instrument Parameters (10/6/12, 10/7/12, 10/10/12); Beam diameter: 21 cm, Pulse rate: 93-107.8 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 65 %, Laser output power: 26% Field of view (FOV): 28 degrees,

Beam wavelength: 1064 nm, Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 448 m AGL: 900 m Average pulse density: 8

Leica ALS60 Instrument Parameters (3/31/13, 4/1/13): Beam diameter: 21 cm, Pulse rate: 93 - 107.8 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 65 %, Laser power: 17 %, Field of view (FOV): 28 degrees, Beam wavelength: 1064 nm,

Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 449 m, AGL: 900 m, Average pulse density: 8

Leica ALS60 Instrument Parameters (6/29/13, 6/30/13): Beam diameter: 21 cm, Pulse rate: 93 - 107.8 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 65 %, Laser power: 26 %, Field of view (FOV): 28 degrees, Beam wavelength: 1064 nm,

Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 449 m, AGL: 900 m, Average pulse density: 8

Leica ALS60 Instrument Parameters (7/24/13): Beam diameter: 23 cm, Pulse rate: 85-99.2 kHz, Maximum returns: 4, Speed: 105 knots, Overlap: 60 %, Laser power: 28.9 %, Field of view (FOV): 30 degrees, Beam wavelength: 1064 nm,

Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, Swath width: 536 m, AGL: 1000 m, Average pulse density: 8

Delivery 2:

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 ALS Post Processor and IPAS TC software 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 ALS postprocessing software, 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 accuracy.

9. The highest hit algorithm was used to create this highest hit DSM.

The NOAA Office for Coastal Management (OCM) downloaded topographic files in .LAZ format from PSLC's website in two separate deliveries. The files contained lidar elevation and intensity measurements.

The data were received in Washington State Plane South Zone 4602, NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid03 model. The vertical units of the data were feet. OCM

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

Delivery 1:

1. The topographic laz files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03.

2. The topographic laz files were converted from a Projected Coordinate System (WA SP South) to a Geographic Coordinate system (NAD83).

3. The topographic laz files' vertical units were converted from feet to meters.

4. The topographic laz files' horizontal units were converted from feet to decimal degrees.

Delivery 2:

1. The topographic laz file 'q47124f1103' was found to contain Class 15 points. These points were changed to Class 2 (Ground).

2. The topographic laz files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03.

3. The topographic laz files were converted from a Projected Coordinate System (WA SP South) to a Geographic Coordinate system (NAD83).

4. The topographic laz files' vertical units were converted from feet to meters.

5. The topographic laz files' horizontal units were converted from feet to decimal degrees.