2013 USACE NCMP Topobathy Lidar (LMSL): Molokai, HI

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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.

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This graphic shows the lidar coverage for the 2013 JALBTCX topobathy project along the shores of Molokai.

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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These data were collected using the CZMIL system. It is owned and operated by the U.S. Army Corps of Engineers (USACE). The system collects topobathy lidar data at 10 kHz and RGB imagery at 2 Hz. A CASI-1500 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 510 equipment. All raw data streams are transferred to the office for downloading and processing in CZMIL's Hydro Fusion 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 packages Fledermaus and PFM_ABE, anomalous data are flagged as invalid and have the withheld bit set.

LAS files are imported into GeoCue V2014.1.21.1, which is a geospatial workflow production and management software tool employed by JALBTCX to perform and monitor production of data products. Upon import into GeoCue, a customized classification macro, built upon the TerraScan V13 module within Microstation V8i, classifies valid topobathy data as ground points (2) and unclassified points (1), and valid bathymetric points (29). Upon completion the macro, the classification results undergo quality control and any misclassified points are manually edited. In areas of dense vegetation the bare earth ground points might be incorrectly classified due to the inability of the laser to penetrate the canopy and reach the bare ground. In these areas, JALBTCX defaults to the algorithm's "ground" surface instead of manually reclassifying those points. They are partitioned into a series of 5km or quarter quad delivery boxes, one Classified LAS file per box. The format of the file is LAS version 1.2. Data are classified as 1 (valid non-ground topographic data), 2 (valid ground topographic data), and 29 (valid bathymetric data). The Geoid12B to HI LMSL vertical adjustment value derived from published NGS control point datasheets for HI, The Molokai, was -0.601 m.

Horizontal positions, provided in decimal degrees of latitude and longitude, are referenced to the North American Datum of 1983 National Adjustment of 2011 (NAD83 PA11). Once converted to orthometric heights, the data are then adjusted to the Local Mean Sea Level (LMSL). Vertical positions are referenced to the (NAD83 PA11) ellipsoid and provided in meters. The 3-D position data are sub-divided into a series of LAS files, which are tiled into quarter-quads or 5km boxes.

The NOAA Office for Coastal Management (OCM) received files in las format from JALBTCX. The files contained LiDAR intensity and elevation measurements and derived products for the island of Molokai. OCM performed the following processing on the data for storage purposes and to make it available within Digital Coast:

1. The LAS files were processed to remove outlier points but maintained original projections information. Tiles were delivered horizontally referenced to geographic coordinate system (decimal degress) and vertical heights are referenced to the adjusted LMSL in meters.