Snippet of an MPEG Animation of the Southern Portion of the Pulley Ridge Study Area

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Frequently-anticipated questions:

What does this data set describe?

Snippet of an MPEG Animation of the Southern Portion of the Pulley Ridge Study Area
Pulley Ridge is a series of drowned barrier islands that extends almost 200 km in 60-100 m water depths. This drowned ridge is located on the Florida Platform in the southeastern Gulf of Mexico about 250 km west of Cape Sable, Florida. This barrier island chain formed during the initial stage of the Holocene marine transgression. These islands were then submerged and left abandoned near the outer edge of the Florida Platform. The southern portion of Pulley Ridge hosts zooxanthellate scleractinian corals, green, red and brown macro algae, and a mix of deep and typically shallow-water tropical fishes. This reef community is in unusually deep water, and its extent and the controls on its distribution were unknown. To address these questions scientists from the U.S. Geological Survey Coastal and Marine Geology Program in cooperation with scientists from the University of South Florida Department of Marine Sciences have completed a detailed mapping of the southernmost 35 km of Pulley Ridge. The area was mapped using multibeam bathymetry, sidescan-sonar imagery, and high-resolution seismic-reflection profiling to define the geologic framework on which the reef is established. Submersible dives, remotely operated vehicle (ROV) transects, and transects of bottom photographs and video were collected to identify the corals and to map their distribution. This extensive suite of data has been compiled and preliminary analysis of the data suggests that the reefs are not tied to the ridge system, but instead are more broadly distributed. Whether reef distribution is controlled by oceanographic conditions or by subtle differences in the substrate that overlies the barrier island system is unclear, and are topics of continued research.
  1. How should this data set be cited?

    Cross, VeeAnn A. , 2005, Snippet of an MPEG Animation of the Southern Portion of the Pulley Ridge Study Area:.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Twichell, David C. , Halley, Robert B. , Ciembronowicz, Kate T. , Jarrett, Bret D. , Hammar-Klose, Erika S. , Hine, Al C. , Locker, Stan D. , and Naar, Dave F. , 2005, GIS Compilation of Data Collected from the Pulley Ridge Deep Coral Reef Region: Open-File Report 2005-1089, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -83.792254
    East_Bounding_Coordinate: -83.591486
    North_Bounding_Coordinate: 25.000776
    South_Bounding_Coordinate: 24.671257

  3. What does it look like?

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

    Calendar_Date: 2005
    Currentness_Reference: publication date

  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?

  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?

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

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)

Why was the data set created?

This animation is provided to provide the 3D visualization relating the SeaBOSS bottom photographs with the high-resolution bathymetry collected in the study area.

How was the data set created?

  1. From what previous works were the data drawn?

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

    (process 1 of 11)
    High-resolution swath bathymetry was converted into a Fledermaus file format (data object) with a colormap applied using the IVS DMAGIC software package.

    (process 2 of 11)
    An ArcView avenue script was used to derive the x and y corner point locations of a SeaBOSS bottom photograph if the photograph was made vertical. This was done by taking the polyline shapefile of the photograph locations to get the direction of travel. Since this polyline shapefile was generated from the point shapefile of photograph locations, each vertex in the polyline represents a photo location. A graphic line, perpendicular to the direction of travel of the polyline, was generated at each vertex of the SeaBOSS polyline. The length of this graphic is a constant value as defined in the script. For this work, the length of the graphic line was set to 200m. This in-house generated script is called createtransectsatvertices.ave.

    (process 3 of 11)
    These graphic lines were then converted to a polyline shapefile.

    (process 4 of 11)
    These polylines were then rotated 45 degrees using the in-house script vac_rotatepolyline.ave.

    (process 5 of 11)
    The script track_startend.ave was then used to add the start and end points (x and y) to each polyline. Other attributes that correspond to each photo location were incorporated into this shapefile. These include the bottom photograph filename corresponding to each line, approximate depth at the center of each transect line, and an upper z-limit (10 meters above the seafloor elevation).

    (process 6 of 11)
    This table of information was then exported to a delimited text file and reformatted using an awk script. The new format incorporated the command line version of the IVS vertical image creator. This command requires the following information:

    mkvimage < -in <imageFile>> [-out <sdOutFile> ] < -start xval yval > < -end xval yval > < -zrange zmin zmax >

    For use within a script running from a command prompt, the text "cmdop" needs to be added at the beginning of the line. This program takes as input an image file that represents a vertically oriented image plane along with the starting and ending locations and z-range. It then creates a Fledermaus formatted SD file representing a vertical slice that can be used in a Fledermaus 3D scene.

    (process 7 of 11)
    A subset of the total number of SeaBOSS bottom photographs was selected. These points were also extracted from the photopnts shapefile into a separate shapefile, while the remaining points were left in a separate shapefile.

    (process 8 of 11)
    The study area was roughly divided into 3 areas: southern, central and northern. This was necessary due to the large number of vertical images that were going to be used. The bathymetry SD files and the point shapefiles representing the selected images and remaining images were loaded into Fledermaus. In addition, the vertical image files corresponding to the southern portion of the study area were also loaded. The following projection parameters were used for the scene: near clipping plane: 0.01 far clipping plane: 250000 scene pushback: 250 global scene scale: 28

    In addition to the data files, a polyline shapefile was also added to the scene which was to represent the approximate flight path for the animation. A vertical exaggeration of 18 was applied to the scene. This exaggeration also applied to the vertical images. The initial vertical extent of each image was 10 meters, but with this additional exaggeration applied, the images remained proportional based on a 200 m width for each image.

    (process 9 of 11)
    Using a Polehemus Isotrak 3D mouse (bat), a flight path was recorded in Fledermaus.

    (process 10 of 11)
    IVS's Movieclient software was used to smooth the resulting flight path and create an MPEG-1 file based on the flight path and the corresponding scene file. Within movieclient, the anti-aliasing parameter was set to 3, with the render magnification parameter set to 2.

    (process 11 of 11)
    VideoMach was then used to extract a very short portion of the animation.

  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?

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

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

How can someone get a copy of the data set?

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

Access_Constraints: None.
The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.

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

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    The user must have an installed program, such as Windows Media Player or RealPlayer, capable of playing an MPEG animation file to view this visualization file.

Who wrote the metadata?

Last modified: 13-May-2005
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)

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

Generated by mp version 2.8.6 on Fri May 13 14:11:06 2005