2011 USACE NCMP Topobathy Lidar: California

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The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

Information about the NOAA Office for Coastal Management (OCM)

This graphic shows the lidar coverage for the 2011 USACE Topobathy Lidar:California data set.

Link to custom download, from the Data Access Viewer (DAV), the raster Digital Elevation Model (DEM) data that were created from this lidar data set.

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.

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Topographic data - These data were collected using the ALS60 lidar system. They are owned by Fugro EarthData and operated through contract. The system collects topographic lidar data at maximum pulse rate of 200 kHz in a wavelength of 1064 nm. A CASI-1500 hyperspectral line scanner is integrated with the system. Aircraft position, velocity and acceleration information are collected by the onboard GPS/IMU system. Raw data were transferred to the office and processed in IPAS software. Aircraft position data are processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. Upon processing, validation and QA/QC in the software packages GeoCue and TerraScan, anomalous data are flagged as invalid and necessary reflights are called. Fugro's proprietary software converts all valid data from ellipsoid to orthometric heights based on the NGS' GEOID09 model and exports topographic data as a series of LAS files with a single file per flightline per 5km box.

Topographic data - 1. The raw lidar data was processed through a minimum block mean algorithm, and points were classified as either bare earth or non-bare earth. 2. User developed macros that factor mean terrain angle and height from the ground were used to determine bare earth point classification. 3. The next phase of the surfacing process was a 2D edit procedure that ensures the accuracy of the automated feature classification. 4. Editors used a combination of imagery, intensity of the lidar reflection, profiles and tin-editing software to assess points. 5. The lidar data was filtered, as necessary, using a quadric error metric to remove redundant points. This method leaves points where there is a change in the slope of surfaces (road ditches) and eliminates points from evenly sloped terrain (flat field) where the points do not affect the surface. 6. The algorithms for filtering data were utilized within Fugro EarthData's proprietary software and commercial software written by TerraSolid. 7. The flight line overlap points were merged back into filtered data set for delivery product. 8. The point cloud data were delivered tiled in LAS 1.0 format; unclassified (1), ground (2), low/noise (7), water (9), and overlap (12). Horizontal positions, provided in decimal degrees of latitude and longitude, are referenced to the North American Datum of 1983 (NAD83). Vertical positions are referenced to the NAD83 ellipsoid and provided in meters. The National Geodetic Survey's (NGS) GEOID09 model is used to transform the vertical positions from ellipsoid to orthometric heights referenced to the North American Vertical Datum of 1988 (NAVD88).

Bathymetric data - These data were collected using the SHOALS-1000T system. It is owned by Fugro Pelagos Inc. and operated through contract. The system collects bathymetric lidar data at 1kHz and RGB imagery at 1Hz. A CASI-2 hyperspectral line scanner is integrated with the system as well. Aircraft position, velocity and acceleration information are collected through a combination of Novatel and POS A/V 410 equipment. All raw data streams are transferred to the office for downloading and processing in SHOALS GCS software. Aircraft position data are processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. Upon inspection and QA/QC in the software package Fledermaus, anomalous data are flagged as invalid. FPI Workbench then converts all valid data from ellipsoid to orthometric heights based on the NGS' GEOID09 model and exports data as a series of bathymetry (H) ASCII files. The bathymetry files contain all of the returns from the bathymetric sensor which include returns both above and below the water. Horizontal positions, provided in decimal degrees of latitude and longitude, are referenced to the North American Datum of 1983 (NAD83). Vertical positions are referenced to the NAD83 ellipsoid and provided in meters. The National Geodetic Survey's (NGS) GEOID09 model is used to transform the vertical positions from ellipsoid to orthometric heights referenced to the North American Vertical Datum of 1988 (NAVD88).

The topographic and bathymetric data were received by the Office for Coastal Management (OCM). The topographic data were in las format and the bathymetric data were in ASCII format. The topographic and bathymetric data were in orthometric (NAVD88) heights and in geographic coordinates. The following steps document the processing of the data for Digital Coast storage and provisioning purposes:

1. The topographic data were converted from orthometric heights to ellipsoid heights using GEOID09.

2. The bathymetric data were converted from orthometric heights to ellipsoid heights using GEOID09.

3. All points were converted to laz format.