Data Management Plan

The Virginia Geographic Information Network (VGIN) contracted with Sanborn to provide LiDAR mapping services for Accomack and Northampton counties on the eastern shore of Virginia in the March of 2010. Utilizing multi-return systems, Light Detection and Ranging (LiDAR) data in the form of 3-dimensional positions of a dense set of mass points was collected for approximately 1090 square miles. Of this 1090 sq mile area, 663 sq miles are over land. Collection and delivery of the lidar data were required to meet the USGS LiDAR Guidelines and Base Specifications, version 13 classification scheme. The data available for download from the NOAA Digital Coast are classified as follows: 1 (Unclassified), 2 (Ground), 7 (Low Point/Noise), 9 (Water), and 10 (Ground points in close proximity to breaklines). This project was a cooperative effort funded by The Nature Conservancy (TNC) - Virginia Office, the University of Virginia's Virginia Coast Long-Term Ecological Research Project (VCR/LT ER) and the U.S. Geological Survey (USGS). Users should be aware that this data was not required to be collected at low tide, therefore, there are some flightlines that were collected at low tide and adjacent flightlines that were not collected at low tide.

Original contact information:

Contact Name: John A. Scrivani

Contact Org: Virginia Information Technologies Agency (VITA)

Phone: 804.416.6207

Email: john.scrivani@vita.virginia.gov

Process Steps:

• 2010-03-01 00:00:00 - Data Collection: Using an Optech 3100 Light Detection And Ranging (LiDAR) system, 101 flight lines of standard density (1.4 meter ground sample distance) data were collected over areas in Accomack, VA (approximately 1090 square miles). Multiple returns were recorded for each laser pulse along with an intensity value for each return. The data acquisition occurred in 6 missions between March 25, 2010 and March 30, 2010. (NOTE: The data received by the Office for Coastal Management had time stamps in GPS seconds of the week instead of adjusted GPS seconds as required by the USGS version 13 specification. The acquisition report stated that the collections occurred between March 25, 2010 and March 30, 2010. An analysis of the flight IDs and the GPS seconds of the week time stamps suggested this was not correct. The GPS seconds of the week increased with each flight line ID as would be expected until the week restarted on flight 101. Flight 1 GPS seconds of the week indicated a Sunday flight and flight 100 indicated a Saturday flight. GPS times were changed from seconds of the week to adjusted GPS times by assuming flights 1-100 were during GPS week 1576 and flight 101 was during GPS week 1577, covering March 21, 2010 to March 28, 2010). During the LIDAR campaign, the Sanborn field crew conducted a GPS field survey to establish final coordinates of the ground base stations for final processing of the base-remote GPS solutions.
• 2010-05-01 00:00:00 - Airborne GPS Processing: Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a Smoothed Best Estimate of Trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. Airborne GPS is differentially processed using the GrafNAV V7.50 software by Waypoint Consulting of Calgary, Alberta, Canada.
• 2010-06-01 00:00:00 - IMU data Processing: IMU data provides information concerning roll, pitch and yaw of collection platform during collection event. IMU information allows the pulse vector to be properly placed in 3D space allowing the distance from the aircraft reference point to be properly positioned on the elevation model surface. The IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada. The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia.
• 2010-07-01 00:00:00 - LIDAR Point Classification The classification and quality control (QC) of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helsinki, Finland.
• 2014-06-20 00:00:00 - The NOAA Office for Coastal Management downloaded the las data from William and Mary in LAS 1.2 format. The data had GPS time issues and there was confusion on the dates of collection. The data downloaded by the Office for Coastal Management had time stamps in GPS seconds of the week instead of adjusted GPS seconds as required by the USGS version 13 specification. The acquisition report stated that the collections occurred between March 25, 2010 and March 30, 2010. An analysis of the flight IDs and the GPS seconds of the week time stamps suggested this was not correct. The GPS seconds of the week increased with each flight line ID as would be expected until the week restarted on flight 101. Flight 1 GPS seconds of the week indicated a Sunday flight and flight 100 indicated a Saturday flight. GPS times were changed from seconds of the week to adjusted GPS times by assuming flights 1-100 were during GPS week 1576 and flight 101 was during GPS week 1577, covering March 21, 2010 to March 28, 2010. NOAA OCM was able to fix the GPS time issues and from this information, was able to determine the date of collection. There was also some discrepancy in the Geoid used by Sanborn to convert from ellipsoid to NAVD88 elevations. Contacted Sanborn and confirmed that Geoid03 was used. The las files contained lidar elevation and intensity measurements. The data were in VA State Plane South, FIPS 4502, NAD83 coordinates, referenced to NAVD88 (Geoid03) vertical datum in feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The data were converted from VA State Plane South coordinates to geographic coordinates. 2. The data were converted from NAVD88 heights to ellipsoid heights using Geoid03. 3. The data were converted from vertical units of feet to meters. 4. The data were filtered for elevation outliers. 5. The data were zipped to laz format.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2634

This data set is dynamically generated based on user-specified parameters.;