2011 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Kittitas-Colockum Study Area

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Simple download of data files.

This graphic shows the lidar coverage for the Kittitas-Colockum counties collected in 2011.

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 survey utilized Leica ALS50 Phase II and ALS 60 sensors in a Cessna Caravan 208B

(dual-mounted 9/15/10). The sensors operate with Automatic Gain Control (AGC) for

intensity correction. Depending on acquisition day weather and terrain, the Leica systems

were set to acquire from =83,000 to 105,900 laser pulses per second (i.e., 83 - 105.9 kHz

pulse rate) and flown at 900-1300 meters above ground level (AGL), capturing a scan angle of

+/- 14 degrees from nadir. These settings were developed to yield points with an avg native pulse

density of more than 8 pulses per sq m over terrestrial surfaces. 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.

Resolved kinematic corrections for aircraft position data using kinematic aircraft GPS

and static ground GPS data.

Software - Waypoint GPS v.8.10, Trimble Geomatics Office v.1.62

2. Developed a smoothed best estimate of trajectory (SBET) file that blends postprocessed

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 v.1.35

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.

Software - ALS Post Processing Software v.2.70

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.10.009

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.10.006

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. Data were then

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

Software - TerraScan v.10.009, TerraModeler v.10.004

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.10.009, ArcMap v. 9.3.1, TerraModeler v.10.004

The NOAA Office for Coastal Management (OCM) downloaded topographic files in LAZ format from PSLC's website.

The files contained lidar easting, northing, elevation, intensity, return number, class, scan angle

and GPS time measurements; the data was received in state plane Washington South (in feet) and

vertical coordinates were referenced to NAVD88 in feet using the Geoid03 model.

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

1. The All-Return LAZ files were checked for bad elevations

2. The laz files were converted from a Projected Coordinate System (SP 4602) to a Geographic Coordinate system (NAD83)

3. The laz files were then converted to ellipsoidal vertical units in meters using the geoid03 conversion.