2007 Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) Topobathy Lidar: Guam

These data were collected for the Government of Guam Department of Public Works and the Government of Guam Office of Homeland

Security from February 18 through May 20, 2007. The data contained in these files contain topographic data collected by the CHARTS

system. The data points representing bare earth have been classified as such using TerraScan. The topographic lidar was collected

across the island of Guam to produce 2 foot contours and bathymetric lidar was collected to fill the areas where no data were

obtained during previous survey efforts. The bathymetric lidar data were collected from the land/water interface seaward to a

depth of 40 meters or laser extinction, whichever came first. This is a classified data set. Classification values are:

Class 1: Unclassified

Class 2: Ground

Class 11: Bathymetric points

Class 14: upland collected bathymetric points (green topo)

The data contain both first and last return lidar data. The topographic lidar data are vertically referenced to Mean Sea Level (MSL)

and the bathymetric lidar data are referenced to Mean Lower Low Water (MLLW).

The purpose of this survey was to collect topographic lidar across the island of Guam to produce 2-foot contours and to collect

bathymetric lidar data to fill the areas where no data were obtained during previous survey efforts. The bathymetric lidar data

were to be collected from the land water interface seaward to a depth of 40 meters or laser extinction, whichever comes first.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/msl/551/supplemental/2007_JALBTCX_Topobathy_Guam_Lidar.kmz

Any conclusions drawn from the analysis of this information are not the responsibility of JALBTCX, the Office for Coastal Management,

or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer;

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no

longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its

limitations.

These data are not attributed. | Quantitative Value: N/A | Quantitative Test Explanation: These data are not attributed.

The data positions were obtained using post processed KGPS methods. The horizontal accuracy of the data is better than +/- 0.75 m.; Quantitative Value: 0.75 meters, Test that produced the value: 1 Sigma

The data positions were obtained using post processed KGPS methods. The vertical accuracy of the data is better than +/- 0.20 m.; Quantitative Value: 0.20 meters, Test that produced the value: 1 Sigma

These data covered the required survey area with minimal gaps in data coverage except near tops of mountains. These gaps are caused

when the ground elevation rises so high that the lidar swath (based on maximum scan angles and altitude) from adjacent flight lines

no longer overlap. The data postings are very consistent with postings nominally at 1.3 m density.

The data provided in this file were tested against ground truth data. At these locations the lidar data matched within 0.20 meters,

and different flight line data agreed within 0.20 meters.