2006 USACE Topobathy Lidar: Lake Michigan (IN), Lake Erie (OH,PA), Lake Huron (MI)

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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.

Fugro Pelagos, Inc. | Type of Source Media: Electronic Mail System

Acquisition - Data were acquired using a SHOALS-1000T. Sensor orientation was measured using a POS AV 410, while

images were acquired at 1Hz using a Duncantech DT4000 digital camera. Prior to survey PDOP was checked and missions

planned to avoid PDOP greater than 3.5. During survey the plane was always within 30km of a GPS ground control point,

to provide a good quality position solution. Final positions were determined using a post-processed inertially aided

Kinematic GPS (KGPS) solution. GPS ground control data were acquired at 1Hz.

Data received by the airborne system were continually monitored for data quality during acquisition operations. Display

windows showed coverage and information about the system status. In addition, center waveforms at 5Hz were shown. All

of this information allowed the airborne operator to assess the quality of data being collected.

The data were collected and processed in geographic coordinates and ellipsoid heights. The positions are

relative to NAD83 in decimal degrees of longitude and latitude. The heights were converted from ellipsoid

to geoid heights (NAVD88) using the Geoid03 model with the results in meters.

Data were processed in the field to verify coverage and data quality.

Processing - Data were processed using the SHOALS Ground Control System (GCS). The GCS includes links to Applanix POSPac

software for GPS and inertial processing, and IVS Fledermaus software for data visualization, 3D editing and tie-line

analysis. Data were processed in NAD83 horizontal and vertical datum. Data were later converted to the NAVD88 vertical

datum using the GEOID03 model. The date and time of each point are also MM:SS.SSSSSS.

Fugro in-house utilities were used to extract XYZ data from the native LiDAR files and split the data in to pre-defined

boxes, each covering approximately 5km of shoreline. ASCII files include: Longitude, Latitude, Elevation, Date, Time,

and Intensity.

Files converted to LDART LAS format (geographic coords, ellipsoid heights,using GEOID03),

sorted by latitude and filtered to eliminate outliers.

Times had originally been stored as POSIX seconds when converted to LAS. This was switched to adjusted GPS time (GPS seconds - 1e9) to conform to the LAS 1.2 standard.

NOAA OCM received the data in LAS v1.2 format. For data storage and Digital Coast provisioning purposes, the data were processed as follows:

1. Heights were converted Ellipsoid heights, horizontal coordinates were converted to geographic coordinates.

2. lastools's Lasground processed the all unclassifed points to have ground classified points as well.

3. LAS files were converted to LAZ and sorted.