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

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Frequently anticipated questions:


What does this data set describe?

Title:
2007 Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) Topobathy Lidar: Guam
Abstract:
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: Water 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).
Supplemental_Information:
A footprint of this data set may be viewed in Google Earth at: <ftp://ftp.csc.noaa.gov/pub/crs/beachmap/qa_docs/gu/2007_JALBTCX_Topobathy_Guam_Lidar.kmz>
  1. How should this data set be cited?

    Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX), and Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Coastal Services Center (CSC), 20071211, 2007 Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) Topobathy Lidar: Guam: NOAA's Ocean Service, Coastal Services Center (CSC), Charleston, SC.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 144.616616
    East_Bounding_Coordinate: 144.962572
    North_Bounding_Coordinate: 13.654497
    South_Bounding_Coordinate: 13.654497

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 18-Feb-2007
    Ending_Date: 20-May-2007
    Currentness_Reference: Ground Condition

  5. What is the general form of this data set?

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: Mean Sea Level
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: Meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
      Depth_System_Definition:
      Depth_Datum_Name: MLLW
      Depth_Resolution: 0.001
      Depth_Distance_Units: Meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Acknowledgement of the Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) would be appreciated in any publications or derived products.

  3. To whom should users address questions about the data?


Why was the data set created?

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.


How was the data set created?

  1. From what previous works were the data drawn?

    Not provided (source 1 of 1)
    (comp.), JALBTCX, Unpublished material, 2007 HI Guam CHARTS Survey.

    Other_Citation_Details: These data were collected by JALBTCX as project number 07006.
    Type_of_Source_Media: hard drive
    Source_Contribution: Not provided

  2. How were the data generated, processed, and modified?

    Date: 14-Nov-2007 (process 1 of 2)
    These data were collected using the CHARTS system. It is owned by the Naval Oceanographic Office and Operated through contract. The system collects topographic lidar data at 20 kHz and hydrographic data at 3 kHz. The system also collects RGB imagery at 1Hz. 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 equipment. Raw data are collected and transferred to the office for downloading and processing in SHOALS GCS software. GPS data are processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. These data are edited using Fledermaus software where anomalous data are removed from the dataset. The edited data are written to the national grid system 1 km tiles using chartsLAS, a program written by NAVO. This program reads data from the original binary format files and produces separate ASCII files for first and last return data. Using a model calculated by NAVO, data were converted from ellipsoid to Mean Sea Level heights using the program datum_shift, written by NAVO. The LAS files output from chartsLAS were read into TerraScan and filters were applied to classify ground points. Points designated as ground are assigned a classification value "2" and all other points are assigned the classification value "1" which represents an unclassified state.

    Person who carried out this activity:

    JALBTCX
    Data Production Manager
    7225 Stennis Airport Road, STE 100
    Kiln, MS 39556
    USA

    228-252-1111 (voice)
    228-252-1133 (FAX)
    shoals-info@sam.usace.army.mil

    Hours_of_Service: 8 am to 5 pm Monday through Friday
    Date: Nov-2010 (process 2 of 2)
    The NOAA Coastal Services Center (CSC) received files in LAS format. The files contained LiDAR intensity and elevation measurements. CSC performed the following processing on the data to make it available within Digital Coast: 1. The data were converted from UTM coordinates to geographic coordinates. 2. The bathymetric lidar classifications were set to class 11. 3. The LAS georeference header files were set to reflect the tidal vertical datums. 4. The LAS header fields were sorted by latitude and updated.

    Person who carried out this activity:

    NOAA Coastal Services Center
    Clearinghouse Manager
    2234 South Hobson Ave.
    Charleston, SC 29405
    US

    843-740-1210 (voice)
    clearinghouse@noaa.gov

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    These data are not attributed.

  2. How accurate are the geographic locations?

    The data positions were obtained using post processed KGPS methods. The horizontal accuracy of the data is better than +/- 0.75 m.

  3. How accurate are the heights or depths?

    The data positions were obtained using post processed KGPS methods. The vertical accuracy of the data is better than +/- 0.20 m.

  4. Where are the gaps in the data? What is missing?

    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.

  5. How consistent are the relationships among the observations, including topology?

    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.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
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.

  1. Who distributes the data set? (Distributor 1 of 1)

    NOAA Coastal Services Center
    Clearinghouse Manager
    2234 South Hobson Ave.
    Charleston, SC 29405-2413

    843-740-1210 (voice)
    clearinghouse@noaa.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Any conclusions drawn from the analysis of this information are not the responsibility of JALBTCX, the Coastal Services Center, or its partners.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    This data can be obtained on-line at the following URL: <http://www.csc.noaa.gov/lidar>


Who wrote the metadata?

Dates:
Last modified: 17-Jun-2013
Metadata author:
NOAA Coastal Services Center
Clearinghouse Manager
Charleston, SC 29405-2413

843-740-1210 (voice)
clearinghouse@noaa.gov

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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