2017 NOAA NGS Topobathy Lidar: Dog Island, FL

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Bulk download of data files in LAZ format, geographic coordinates, orthometric heights. Note that the vertical datum (hence elevations) of the files here are different than described in this document.

Information on the NOAA Office for Coastal Management (OCM)

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.

This graphic displays the footprint for this lidar data set.

Data for the Dog Island project was acquired by NOAA using a Riegl VQ880G sensor. All delivered lidar data is referenced to:

Horizontal Datum-NAD83 (2011) epoch: 2010

Projection-UTM Zone 16 North

Horizontal Units-meters

Vertical Datum-NAD83(2011) epoch: 2010

Vertical Units-meters

This dataset encompasses 616 500 m x 500 m lidar tiles. Both green lidar data and NIR lidar data was acquired.

NOAA acquired, calibrated, and performed the refraction correction of the lidar data. Light travels at different speeds in air versus water and its direction of travel or angle is changed or refracted when entering the water column. The refraction correction process corrects for this difference by adjusting the depth (distance traveled) and horizontal position (change of angle/direction) of the lidar data acquired within water.

Dewberry received the calibrated green and NIR data and verified complete coverage. Relative accuracy of the green swaths compared to overlapping and adjacent green swaths as well as the relative accuracy of green swaths compared to overlapping and adjacent NIR swaths was verified through the use of Delta-Z (DZ) orthos created in GeoCue software. Intraswath or within a swath relative accuracy was verified using Quick Terrain Modeler. Profiles of elevated planar features, such as roofs, were used to verify horizontal alignment between overlapping swaths.

Dewberry used algorithms in TerraScan to create the initial ground/submerged topography surface.

Dewberry created 2-D breaklines by digitizing breaklines in a 2-D environment using intensity imagery as a reference. Dewberry used the 2-D breaklines to classify the bathymetric bottom and ground points properly in TerraScan.

All lidar data was peer-reviewed. Dewberry's QAQC also included creating void polygons for use during review. All necessary edits were applied to the dataset. GeoCue software was used to update LAS header information, including all projection and coordinate reference system information. The final lidar data are in LAS format 1.2 and point data record format 3.

The final classificaton scheme is as follows:

1-Unclassified

2-Ground

7-Topographic Noise

22-Bathymetric Noise

25-Water Column

26-Bathymetric Bottom

27-Water surface

All data is then verified by an Independent QC department within Dewberry. The independent QC is performed by separate analysts who do not perform manual classification or editing. The independent QC involves quantitative and qualitative reviews.

The NOAA Office for Coastal Management (OCM) received 616 files in las 1.2 format. The files contained lidar intensity and elevation measurements for the project area. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. Converted from UTM Zone 16 coordinates to geographic coordinates

3. Sorted by gpstime

4. Compressed the data using laszip