2004 USACE Puerto Rico Lidar

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Frequently anticipated questions:


What does this data set describe?

Title: 2004 USACE Puerto Rico Lidar
Abstract:
This record describes Light Detection and Ranging (Lidar) data acquired for the island of Puerto Rico. The data were acquired for USACE, St. Louis District by 3001, Inc., between January 10 and February 8, 2004. The mission was flown at a density sufficient to support a maximum final post spacing of 6 feet for unobscured areas. The Puerto Rico LiDAR Survey was collected under the guidance of a Professional Mapper/Surveyor.
Supplemental_Information:
The Lidar QA/QC Quantitative and Qualitative Assessment Report for this data set may be viewed at: <ftp://ftp.csc.noaa.gov/pub/crs/beachmap/qa_docs/pr/lidarqaqcreport_puertorico_final.pdf> A footprint of this data set may be viewed in Google Earth at: <ftp://ftp.csc.noaa.gov/pub/crs/beachmap/qa_docs/pr/2004_USACE_Puerto_Rico_Lidar.kmz>
  1. How should this data set be cited?

    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Coastal Services Center (CSC), and USACE, St. Louis District, 2007, 2004 USACE Puerto Rico Lidar: NOAA's Ocean Service, Coastal Services Center (CSC), Charleston, SC.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -67.271346
    East_Bounding_Coordinate: -65.204146
    North_Bounding_Coordinate: 18.515932
    South_Bounding_Coordinate: 17.913132

  3. What does it look like?

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

    Beginning_Date: 10-Jan-2004
    Ending_Date: 08-Feb-2004
    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?

      This is a Point 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: Ellipsoid
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: Meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    LAS
    Lidar point cloud LAS 1.0 format (Source: "ASPRS LAS 1.0 Format Standard, May, 9, 2003")


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?

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

    3001, Inc.
    LiDAR Department
    501 Robert Rd., 2nd floor
    Slidell, LA 70458
    USA

    (985) 661- 3001 (voice)
    (985) 649- 5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT


Why was the data set created?

The Puerto Rico LiDAR dataset will support the creation of Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM) and anintegrated ground and surface water model.


How was the data set created?

  1. From what previous works were the data drawn?

    Raw Lidar Scan Data (source 1 of 1)
    USACE, St. Louis District, 2007, Puerto Rico LiDAR Survey.

    Type_of_Source_Media: online
    Source_Contribution:
    The Puerto Rico LiDAR Survey was acquired for USACE, St. Louis District and processed by 3001, Inc.

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

    Date: 2007 (process 1 of 6)
    The ABGPS, inertial measurement unit (IMU), and raw scans are collected during the LiDAR aerial survey. The ABGPS monitors the xyz position of thesensor and the IMU monitors the orientation. During the aerial survey laser pulses reflected from features on the ground surface are detected bythe receiver optics and collected by the data logger. GPS locations are based on data collection receivers on the aircraft and base stations on theground. The ground base stations are placed no more than 35 km radius from the flight survey area.

    Person who carried out this activity:

    3001, Inc.
    Lidar Department
    501 Robert Blvd, 2nd Floor
    Slidell, LA 70458
    USA

    (985) 661-3001 (voice)
    (985) 649-5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT
    Date: 2007 (process 2 of 6)
    The ABGPS, IMU, and raw scans are integrated using proprietary software developed by the Leica Geosystems and delivered with the Leica ALS50System. The resultant file is in a LAS binary file format. The LAS file version 1.0 format can easily transferred from one file format to another.It is a binary file format that maintains information specific to the LiDAR data (return#, intensity value, xyz, etc.). The resultant points areproduced in the State Plane Puerto Rico FIPS 5200 coordinate system, with units in feet and referenced to the NAD83 horizontal datum and NAVD88vertical datum.

    Person who carried out this activity:

    3001, Inc.
    Lidar Department
    501 Robert Blvd, 2nd Floor
    Slidell, LA 70458
    USA

    (985) 661-3001 (voice)
    (985) 649-5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT
    Date: 2007 (process 3 of 6)
    The unedited data are classified to facilitate the application of the appropriate feature extraction filters. A combination of proprietary filtersis applied as appropriate for the production of bare-earth digital terrain models (DTMs). Interactive editing methods are applied to those areaswhere it is inappropriate or impossible to use the feature extraction filters, based upon the design criteria and/or limitations of the relevantfilters. These same feature extraction filters are used to produce elevation height surfaces.

    Person who carried out this activity:

    3001, Inc.
    Lidar Department
    501 Robert Blvd, 2nd Floor
    Slidell, LA 70458
    USA

    (985) 661-3001 (voice)
    (985) 649-5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT
    Date: 2007 (process 4 of 6)
    Filtered and edited data are subjected to rigorous QA/QC according to the 3001 Inc. Quality Control Plan and procedures. Very briefly, a seriesof quantitative and visual procedures are employed to validate the accuracy and consistency of the filtered and edited data. Ground control isestablished by 3001, Inc. and GPS-derived ground control points (GCPs) points in various areas of dominant and prescribed land cover. These pointsare coded according to landcover, surface material and ground control suitability. A suitable number of points are selected for calculation of astatistically significant accuracy assessment as per the requirements of the National Standard for Spatial Data Accuracy. A spatial proximityanalysis is used to select edited LiDAR data points within a specified distance of the relevant GCPs. A search radius decision rule is appliedwith consideration of terrain complexity, cumulative error and adequate sample size. Accuracy validation and evaluation is accomplished usingproprietary software to apply relevant statistical routines for calculation of Root Mean Square Error (RMSE) and the National Standard for SpatialData Accuracy (NSSDA) according the Federal Geographic Data Committee (FGDC) specifications.

    Person who carried out this activity:

    3001, Inc.
    Lidar Department
    501 Robert Blvd, 2nd Floor
    Slidell, LA 70458
    USA

    (985) 661-3001 (voice)
    (985) 649-5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT
    Date: 2007 (process 5 of 6)
    The LiDAR mass points were delivered in ASPRS LAS 1.0 format. The header file for each dataset is complete as defined by the LAS 1.0 specification.The LAS files do not include overlap. The delivered tiles are suitable for seamless topographic data mosaics that include no "no data" areas. Thenames of the tiles are left padded with zeros as required to achieve a five character length and all files utilize the LAS file extension.

    Person who carried out this activity:

    3001, Inc.
    Lidar Department
    501 Robert Blvd, 2nd Floor
    Slidell, LA 70458
    USA

    (985) 661-3001 (voice)
    (985) 649-5082 (FAX)
    lidar@3001inc.com

    Hours_of_Service: 8:00 - 5:00 CDT
    Date: 07-Dec-2010 (process 6 of 6)
    The NOAA Coastal Services Center (CSC) received the files in las format. The files contained Lidar elevation and intensity measurements.The data were in projected in Puerto Rico State Plane Coordinates (FIPS 5200/NAD83), and referenced to the orthometric datum of NAVD88 utilizingGeoid 99. Both planar and vertical units were measured in feet. CSC performed the following processing to the data to make it availablewithin the Digital Coast:1. The data were converted from State Plane Coordinates (NAD83; ft) to UTM coordinates (Zone 20/NAD83; m).2. The vertical units of the data were converted from NAVD88 (ft) to NAVD88 (m).3. The data were re-tiled using MARS software.4. The data were reclassified such that all classifications were set to Class 0.5. The data were filtered to Bare Earth (Class 2) and Unclassified (Class 1) using an automated process in LASEdit.6. The data were converted from UTM coordinates (Zone 20/NAD83) to geographic coordinates (NAD83) and ellipsoidal elevations (GRS80) using Geoid 99.7. The LAS data were sorted by latitude and the headers were updated.

    Person who carried out this activity:

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

    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?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

    The accuracy assessment was performed using a standard method to compute the root mean square error (RMSE) based on a comparison of groundcontrol points (GCP) and filtered LiDAR data points. Filtered LiDAR data has had vegetation and cultural features removed and by analysisrepresents bare-earth elevations. Testing was performed prior to gridding of the filtered LiDAR data points and construction of theIntergraph .dtm file format. The RMSE figure was used to compute the vertical National Standard for Spatial Data Accuracy (NSSDA). Ground controlwas established by 3001, Inc. A spatial proximity analysis was used to select edited LiDAR data points contiguous to the relevant GCPs. A searchradius decision rule is applied with consideration of terrain complexity, cumulative error and adequate sample size. Cumulative error results fromthe errors inherent in the various sources of horizontal measurement. These sources include the airborne GPS, GCPs and the uncertainty of theaccuracy of the LiDAR data points. This accuracy is achieved prior to the sub-sampling that occurs through integration with the inertialmeasurement unit (IMU) positions that are recorded. It is unclear at this time whether the initial accuracy is maintained. The horizontal accuracyof the GCPs is estimated to be in the range of approximately 1 to 1.6 feet. Finally, sample size was considered. The specification for the NationalStandard for Spatial Data Accuracy is a minimum of 20 points to conduct a statistically significant accuracy evaluation (Minnesota Planning, 1999,Positional Accuracy Handbook, Minnesota Planning Land Management Information Center, St. Paul, Minnesota., p.3). Most statistical texts indicatethat a minimum of 30 sample points provide a reasonable Approximation of a normal distribution. The intent of the NSSDA is to reflect the geographicarea of interest and the distribution of error in the data set (Federal Geographic Data Committee, 1998, Geospatial National Standard for SpatialData Accuracy, Federal Geographic Data Committee Secretariat, Reston, Virginia, p.3-4). Additional steps were taken to ensure the vertical accuracyof the LiDAR data including: Step 1: Precision Bore sighting (Check Edge-matching) Step 2: Compare the LiDAR data to the Field Survey(Field survey is to FEMA specifications and more stringent internal specifications) Step 3: Automated Filtering Step 4: Manual Editing (QualityControl) Step 5: 3-D digitizing and Photogrammetric Compilation of hydrographic breaklines.

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

    At the end of each flight, the Lidar data was processed to check for complete coverage and to verify that there were no voids in data coverage.

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

    Unknown


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 representactual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgement ofUSACE, St. Louis District would be appreciated in products derived from these data.

  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 the Coastal Services Centeror its partners.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 17-Jul-2014
Metadata author:
NOAA Coastal Services Center
Clearinghouse Manager
2234 South Hobson Ave.
Charleston, SC 29405-2413

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

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


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