2016 NOAA Topobathy Lidar: Upper Lake Michigan Islands

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Simple download of data files.

This graphic shows the lidar coverage for the 2015 - 2016 topobathy lidar acquisition for the islands in Upper Lake Michigan.

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.

Data for the Beaver Island Archipelago and South Manitou Island project was acquired by Leading Edge Geomatics using a Leica Chiroptera II Bathymetric and Topographic lidar sensor. All delivered lidar data is referenced to:

Horizontal Datum-NAD83 (2011) epoch: 2010

Projection-UTM Zone 16 North

Horizontal Units-meters

Vertical Datum-NAVD88, GEOID12B

Vertical Units-meters

This dataset encompasses 3,361 500m x 500m tiles. Both green lidar data and NIR lidar data was acquired.

Leading Edge Geomatics acquired, calibrated and performed the refraction correction to the lidar data.

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 then verified absolute vertical accuracy of the swath data prior to full-scale production.

Dewberry used ArcGIS to create 2-D breaklines. The bathymetric points exported by the Leica processing software were aggregated into polygons. These 2D breaklines representing the bathy areas were manually reviewed and adjusted where necessary to ensure all well-defined hydrographic features (at 1:1200-scale) were captured with breaklines.

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

Dewberry used the 2-D breaklines to classify the bathymetric bottom and ground points properly in TerraScan.

Dewberry filtered out an issue with artifacts caused by scanner noise for one mission in the project. The issue cause a single scan rotation of pulses to be much noisier and have a higher spatial distribution of bathymetric points. Dewberry used the neighboring less noisy points to help select the actual bathymetric points in these areas helping to remove the artifacts and create a smooth consistent transition from low noise to high noise areas.

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 1.4 and point data record format 6.

The final classification scheme is as follows:

0-Created, never classified

1-Unclassified

2-Ground

40-Bathymetric bottom

41-Water surface

42-Derived water surface

43-Submerged object, not otherwise specified

44-International Hydrographic Organization (IHO) S-57 objects

45-No bottom found

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 3361 files in las 1.4 format. The files contained lidar intensity and elevation measurements for the project area in upper Lake Michigan. Horizontal positions were provided in UTM Zone 16 coordinates, referenced to the North American Datum of 1983 National Adjustment of 2011 (NAD83 NA11). Vertical positions were referenced to NAVD88 (Geoid12b)and provided in meters. Data classification review showed that the only classifications present in the data are: 0 - never classified, 1 - unclassified, 2- ground, 40 - bathy bottom, 41 - water surface, 42 - derived water surface, 45 - no bathy bottom found. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. Removed elevation outliers below -105 meters ellipsoid height

2. Converted from UTM Zone 16 coordinates to geographic coordinates 3. Converted from NAVD88 elevations to ellipsoid elevations using Geoid12b 4. 4. Sorted by gpstime

5. Compressed the data using laszip