Data Management Plan

USGS Contract Number: 01CRCN0014

In Spring, 2006 Sanborn was contracted by the USGS to survey aprocimately 1,735 square miles of western Whatcom and Skagit Counties in Washington state. All data was collected during ideal conditions (rivers at or below mean level,

leaf off, etc.).

For this collect two sensors were used: The Leica ALS-50 (High Relief Collection) and Optech 2050 (High and Low Relief Collection). LiDAR calibrations were performed to determine and therefore eliminate systematic

biases that occur between the the two sensors. Once the biases were determined they were modeled out. The Leica ALS-50 produced an average point spacing of 1.4 meters. The Optech 2050 produced an average point spacing

of 1.3 meters. All points are classified as Class 2 (Ground) which includes water points and any possibly remaining artifacts.

Leica ALS-50 LiDAR Acquisition Paramters:

Avg. Altitude: 1,500 meters AGL

Airspeed: ~120 Knots

Scan Freq: 36 Hertz

Scan Width Half Angle: 36 Degrees

Pulse Rate: 60,000 Hertz

Overlap: 44-60%

Optech 2050 LiDAR Acquisition Parameters:

Avg. Altitude: 1,200 meters AGL

Airspeed: ~120 Knots

Scan Freq: 30 Hertz

Scan Width Half Angle: 40 Degrees

Pulse Rate: 50,000 Hertz

Overlap: 30-50%

Process Steps:

• 2006-01-01 00:00:00 - Final post-processing of LiDAR data involves several steps. The airborne GPS data was post-processed using Waypoint's GravNAVTM software (version 7.5). A fixed-bias carrier phase solution was computed in both the forward and reverse chronological directions. The data was processed for both base stations and combined. In the event that the solution worsened as a result of the combination of both solutions the best of both solutions was used to yield more accurate data. The GPS trajectory was combined with the raw IMU data and post-processed using Applanix Inc.'s POSPROC (version 4.3) Kalman Filtering software. This results in a two-fold improvement in the attitude accuracies over the real-time INS data. The best estimated trajectory (BET) and refined attitude data are then reintroduced into the LEICA ALS post processor or REALM Survey Suite OPTECH to compute the laser point-positions. The trajectory is then combined with the attitude data and laser range measurements to produce the 3-dimensional coordinates of the mass points. All return values are produced within ALS Post Processing software or REALM Survey Suite OPTECH software. The multi-return information minus the last return provides a useful depiction of the "canopy" within the project area. The last return is further processed to obtain the "Bare Earth Dataset" as a deliverable. All LiDAR data is processed using the binary LAS format 1.0 file format. LiDAR filtering was accomplished using TerraSolid, TerraScan LiDAR processing and modeling software. The filtering process reclassifies all the data into classes within the LAS formatted file based scheme set using the LAS format 1.0 specifications or by the client. Once the data is classified, the entire data set is reviewed and manually edited for anomalies that are outside the required guidelines of the product specification or contract guidelines, whichever apply. The coordinate and datum transformations were then applied to the data set to reflect the required deliverable projection, coordinate and datum systems as provided in the contract. The final data is in State Plane Washington North Coordinate System with the horizontal and vertical units being in feet.
• 2013-01-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received topographic file in ASCII .XYZ format. The files contained lidar elevation measurements. The data were received in Washington State Plane North Zone 4601, NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid99 model. The vertical units of the data were feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The ASCII .XYZ files were converted to LAS version 1.1 using Global Mapper. 2. All points in Class 0 (Never Classified) were changed to Class 2 (Ground). This includes water points. 3. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid99. 4. The topographic las files were converted from a Projected Coordinate System (WA SP North) to a Geographic Coordinate system (GCS). 5. The topographic las files' vertical units were converted from feet to meters. 6. The topographic las files' horizontal units were converted from feet to decimal degrees.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=1451

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