Accuracy Assessment Sites - Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands (2009)

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Frequently anticipated questions:


What does this data set describe?

Title:
Accuracy Assessment Sites - Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands (2009)
Abstract:
Benthic habitat maps of the moderate-depth marine environment of St. John, U.S. Virgin Islands were created using a combination of semi-automated classification and visual interpretation techniques of acoustic imagery. The objective of this effort, conducted by NOAA's Center for Coastal Monitoring and Assessment - Biogeography Branch in partnership with the U.S. National Park Service (NPS), was to provide spatially-explicit information describing the moderate-depth (30 - 60 m) benthic habitat types and live coral cover present in and around VICRNM's southern boundaries. The data contained in this shapefile represent the position of the drop camera as it drifted over 299 accuracy assessment (AA) sites explored by NOAA field scientists.
Supplemental_Information:
Data were collected on 299 ground validation sites over a two-week field mission from 5/31/09 to 6/7/09 aboard U.S. National Park Service small research vessels. Based on guidelines from other recent NOAA accuracy assessment analyses (Battista et al. 2007), a minimum of 25 points were assigned to each of the detailed structure classes within the draft habitat map. Additional points were distributed based on the proportion of area of each structure class in the map. Several pre-selected sites were inaccessible by field scientists or were not classified due to visibility restrictions.
  1. How should this data set be cited?

    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Branch, 2009, Accuracy Assessment Sites - Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands (2009): NOAA's Ocean Service, National Centers for Coastal Ocean Science (NCCOS), Silver Spring, MD.

    Online Links:

    Other_Citation_Details:
    Please use citation for the written document "Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands" when using these data.
    This is part of the following larger work.

    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Branch, 2009, Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands: NOAA National Centers for Coastal Ocean Science, Silver Spring, MD.

    Other_Citation_Details:
    Costa, B.M., L.J. Bauer, T.A. Battista, P.W. Mueller and M.E. Monaco. 2009. Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands. NOAA Technical Memorandum NOS NCCOS 105. Silver Spring, MD. 55 pp.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -64.792032
    East_Bounding_Coordinate: -64.661842
    North_Bounding_Coordinate: 18.311470
    South_Bounding_Coordinate: 18.238453

  3. What does it look like?

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

    Beginning_Date: 31-May-2009
    Beginning_Time: unknown
    Ending_Date: 07-Jun-2009
    Ending_Time: unknown
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Entity Point (8018)

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 20
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -63.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using Coordinate Pair
      Abscissae (x-coordinates) are specified to the nearest 0.000001
      Ordinates (y-coordinates) are specified to the nearest 0.000001
      Planar coordinates are specified in meters

      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.

  7. How does the data set describe geographic features?

    AAData_ModerateDepth_Sites
    Shapefile attribute table (Source: None)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Source
    On what mission was the video collected (Source: NOAA)

    Unknown

    Site_Type
    Type of drop camera point (i.e. GV or AA) (Source: NOAA)

    Unknown

    Site_ID
    Unique identifier for each accuracy assessment site (Source: NOAA)

    Formal codeset
    Codeset Name:Arbitrarily defined unique code
    Codeset Source:Specific to this field mission

    VideoName
    Name of video associated with site (Source: NOAA)

    Unknown

    Max_PDOP
    Maximum Positional Dilution of Precision (Source: Automatically generated by Trimble)

    Unknown

    Max_HDOP
    Maximum Horizontal Dilution of Precision (Source: Automatically generated by Trimble)

    Unknown

    GPS_Date
    Date of logged position (Source: Automatically generated by Trimble)

    Range of values
    Minimum:20090531
    Maximum:20090607

    GPS_Time
    Time of logged position (Source: Automatically generated by Trimble)

    Range of values
    Minimum:06:00:00am
    Maximum:06:00:00pm

    Vert_Prec
    Vertical Precision (Source: Automatically generated by Trimble)

    in meters

    Horz_Prec
    Hortizontal Precision (Source: Automatically generated by Trimble)

    in meters

    Entity_and_Attribute_Overview:
    Specific details of the attributes and values therein can be found in Chapter 1: Benthic Habitat Classification Scheme of "Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands" (Costa et al. 2009)
    Entity_and_Attribute_Detail_Citation:
    Costa, B.M., L.J. Bauer, T.A. Battista, P.W. Mueller and M.E. Monaco. 2009. Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands. NOAA Technical Memorandum NOS NCCOS 105. Silver Spring, MD. 55 pp.


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?

    Costa, B.M., L.J. Bauer, T.A. Battista, P.W. Mueller and M.E. Monaco. 2009. Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands. NOAA Technical Memorandum NOS NCCOS 105. Silver Spring, MD. 55 pp.

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

    Bryan Costa
    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Branch
    1305 East West Highway, N-SCI-1, SSMC 4, 9th Floor
    Silver Spring, MD 20910

    301-713-3028 x146 (voice)
    301-713-4384 (FAX)
    bryan.costa@noaa.gov

    Hours_of_Service: 0800 - 1700, Monday to Friday, EST


Why was the data set created?

The purpose of this survey data was to collect information on current habitat conditions at random locations throughout the mapping area. Locations were determined by an iterative, GIS-based, stratified random sampling technique to ensure that all bottom classifications would be assessed. This information was used to evaluate the thematic accuracy of the St. John moderate-depth benthic habitat map.


How was the data set created?

  1. From what previous works were the data drawn?

    Trimble SSF files (source 1 of 1)
    NOAA, 2009, GPS data.

    Type_of_Source_Media: GPS data
    Source_Contribution:
    GPS data, which were originally recorded as code-phase signals in Trimble SSF format, were differentially post-processed to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH).

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

    Date: 2009 (process 1 of 4)
    A benthic habitat map was generated from acoustic imagery and ground validation points using a combination of semi-automated classification and visual interpretation techniques. Target locations for the accuracy assessment of this habitat map were determined by an iterative, GIS-based, stratified random sampling technique to ensure that all bottom classifications would be assessed. Based on guidelines from other recent accuracy assessment analyses (Battista et al. 2007), a minimum of 25 points were assigned to each of the detailed structure classes within the draft habitat map. Additional points were distributed based on the proportion of area of each structure class in the map. Points were randomly placed within each class using Hawth's Analysis Tools (Beyer, 2004) in ArcGIS. Next, the number of points that fell within each detailed primary cover class was calculated. Where necessary, additional points were randomly added and re-distributed from classes with many points to ensure that there was a minimum of 25 points within each detailed cover class.

    Date: 2009 (process 2 of 4)
    NOAA field scientists explored the accuracy assessment locations with a suite of assessment techniques depending on the conditions at each site. Sample locations were navigated to using a hand-held Garmin 76 CS WAAS-enabled GPS unit. Underwater video from a SeaViewer Sea-Drop 950 camera was taken at each site. A weight was tied to the bottom of the camera to help lower the camera to the bottom, and the camera operator adjusted the camera position to get a downward and side view of the habitat at each location. Video length depended on the habitat type and vessel drift, ranging from approximately 30 seconds to two minutes. Videos of large, homogeneous sand habitats were generally short while heterogeneous coral reef habitats (especially edges) were typically longer. While the video was being recorded, GPS waypoints were recorded on board the vessel using a Trimble GeoXT GPS receivers. This resulted in a string of epics that tracked boat position at each site. An observer categorized each site according to the video for each level of the map classification scheme: major/detailed geomorphological structure, major/detailed biological cover, and percent coral. Data was entered into a custom data dictionary on the Trimble data logger and recorded on waterproof data sheets.

    Date: 2009 (process 3 of 4)
    Trimble Pathfinder Office software was used to post process and differentially correct the raw GPS data to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH).

    Date: 2009 (process 4 of 4)
    Ultimately, precisely positioned GPS positions and the associated classification data were viewed in a GIS to assess the accuracy of the draft benthic habitat map.

  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?

    The points in this thematic data layer were acquired by GPS data using a Trimble GeoXT receiver with a customized data dictionary designed to reflect the habitat classification scheme described in "Moderate-Depth Benthic Habitats of St. John, U.S. Virgin Islands" (Costa et al. 2009). All habitat determinations were made in the field by trained NOAA scientists, recorded in the GPS data logger and seamlessly transferred to ArcGIS shapefiles using Trimble Pathfinder Office software. Attributes are all expected to be correct.

  2. How accurate are the geographic locations?

    The true positional accuracy of individual epics was determined to be within 1 m for 96% of the logged points. For each survey site, individual epics were averaged to generate a mean GPS point for each location.

  3. How accurate are the heights or depths?

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

    299 field positions were occupied and habitat characterizations were conducted for accuracy assessment during this work. These data were plotted in concert with remotely sensed imagery to assess the benthic habitat classifications at random locations throughoout the map. Further analysis was conducted to calculate a suite of thematic accuracy assessment metrics and is described in Costaet al. (2009).

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

    Data points with accompanying attribute information were collected with mapping-grade GPS receivers. The data were post processed for differential correction to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH). Site information was recorded in the field both in a data dictionary within the GPS receiver and on waterproof field sheets. A comparison between soft and hard copy data records were completed to ensure attribute collection consistency.

    Furthermore, underwater video was recorded at each site to maintain a record of habitat condition. This video was reviewed by NOAA staff in the office to ensure correct habitat attribution was made in the field.

    All errors were identified through these quality assurance techniques and corrected. This file is believed to be logically consistent.


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: Not for navigation.

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

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program
    1305 East West Highway, N-SCI-1, SSMC 4, 9th Floor
    Silver Spring, MD 20910

    301-713-3028 (voice)
    301-713-4384 (FAX)

    Hours_of_Service: 0800 - 1700, Monday to Friday, EST
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) is publishing this data on their website. NCCOS Biogeography Branch does not guarantee the accuracy of the geographic features or attributes. Please see the written report and metadata records for each data set for complete information on the source, limitations, and proper use.

  4. How can I download or order the data?

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

    Contact NOAA for distribution options (see Distributor).


Who wrote the metadata?

Dates:
Last modified: 20-Dec-2012
Last Reviewed: 26-Feb-2010
Metadata author:
Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Branch
1305 East West Highway, N-SCI-1, SSMC 4, 9th Floor
Silver Spring, MD 20910

(301) 713-3028 (voice)

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


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