GIS Data Catalog

Individual SBET files from each production block were appended into single shapefile.

Shapefile was imported into geodatabase featureclass.

Date of file was added to each record, so that each point could be identified by date.

Only items that provided information about the point location, date and time were not removed.

Acquisition.

Quantum Spatial collected the PSLC King County LiDAR Delivery 4, Block 1 LiDAR data between 03/26/16 and 08/27/16.

The survey used both a Leica ALS70 (service Pack 2) and ALS80 laser system mounted in a Cessna Caravan 208B.

Data was collected using a multi pulse flight plan.

Ground level GPS and aircraft IMU were collected during the flight.

Sensor: Leica ALS80 (03/26/2016, 03/30/2016): Maximum returns: unlimited Nominal pulse density: 8 ppsm pulses/m^2 Nominal pulse spacing: .35 m AGL: 1200 m Speed: 145 knots FOV: 40° Scan frequency: 50.0 hz Pulse rate: 400 kHz Pulse duration: 2.5 ns Pulse width: 26.4 cm Wavelength: 1064 nm Pulses in air mode: Multiple Pulses in Air Beam divergence: 22 mrads Swath width: 874 m Overlap: 63% Sensor: Leica ALS80 (08/13/2016, 08/14/2016, 08/21/2016): Maximum returns: unlimited Nominal pulse density: 8 ppsm pulses/m^2 Nominal pulse spacing: .35 m AGL: 1450 m Speed: 100 knots FOV: 30° Scan frequency: 53.4 hz Pulse rate: 190.8 kHz Pulse duration: 2.5 ns Pulse width: 31.9 cm Wavelength: 1064 nm Pulses in air mode: Single Pulse in Air Beam divergence: 22 mrads Swath width: 777 m Overlap: 62% Sensor: Leica ALS70 (08/14/2016, 08/15/2016, 08/16/2016, 08/17/2016, 8/18/2016, 8/19/2016, 8/20/2016): Maximum returns: unlimited Nominal pulse density: 8 ppsm pulses/m^2 Nominal pulse spacing: .35 m AGL: 1450 m Speed: 100 knots FOV: 30° Scan frequency: 53.6 hz Pulse rate: 192.6 kHz Pulse duration: 9 ns Pulse width: 31.9 cm Wavelength: 1064 nm Pulses in air mode: Single Pulse in Air Beam divergence: 22 mrads Swath width: 777 m Overlap: 61% Sensor: Leica ALS70 (08/25/2016, 08/26/2016, 8/27/2016): Maximum returns: unlimited Nominal pulse density: 8 ppsm pulses/m^2 Nominal pulse spacing: .35 m AGL: 1650 m Speed: 100 knots FOV: 24° Scan frequency: 53.2 hz Pulse rate: 172.2 kHz Pulse duration: 9 ns Pulse width: 36.3 cm Wavelength: 1064 nm Pulses in air mode: Single Pulse in Air Beam divergence: 22 mrads Swath width: 701 m Overlap: 64% .

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 Waypoint Inertial Explorer and Leica Cloudpro 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 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 ground survey points collected to verify the vertical accuracy.