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Table of Contents:

OF 2004-1014

Disc Contents

Geologic
    Discussion

Data/GIS

• Getting Started

  • GIS Specifics

• Navigation

• Seismic-Reflection

• Sidescan-sonar mosaics

• Ground-Truthing

Metadata/Data
    Catalog

References Cited

Contacts

Getting Started

This research project integrates several different types of data. These data types include seismic-reflection profiles, sidescan-sonar imagery, bottom photographs, and in some places sediment samples. These data types have been put into a form easily accessible through a Geographic Information System (GIS). This project employs the Environmental Systems Research Institute's ArcView as the GIS mapping tool. Therefore the GIS datasets made available are compatible with that software system. The various links to the data not only provide access to the data, but also a discussion of the data format and how the data were collected. How these data are organized may not be necessarily intuitive, so a brief explanation on where to find information will follow. The data can be downloaded from these locations, or from the Metadata/Data Catalog page.

The navigation link points to the ASCII reformatted raw navigation as it was recorded from the GPS system from the 2000 cruise. In addition to this form of raw navigation, processed navigation in the form of ArcView shapefiles from the geophysical survey is also available. These include survey tracklines (polylines), and seismic-reflection shotpoint navigation (points). Navigation pertaining to ground-truthing operations is available under the Ground-Truthing section.

Seismic-reflection data, in SEG-Y format, are available on this DVD. Although SEG-Y data cannot be used in ArcView directly, JPEG images generated from the seismic-reflection profiles can be linked to the survey tracklines. The seismic-reflection link allows the SEG-Y data to be downloaded, as well as offering an image preview of the profiles. The JPEG images of the profiles are also available from that location.

Sidescan-sonar imagery is provided in the format of georeferenced image mosaics. These mosaics are provided in both TIFF and MrSid formats in geographic coordinates and Washington State Plane South projection. These data are provided through the sidescan-sonar mosaic link.

The ground-truthing portion of the project involved sediment samples, bottom photography, and bottom video. For work completed in 2000, bottom images and their locations are available. These locations are available as a point shapefile with the video tracklines provided as a polyline shapefile. For the ground-truth work completed in 2002, both bottom images and sediment sample analyses are provided. The locations for this information are in the form of point shapefiles. Data from these two years are provided through the ground-truthing link.

GIS Specifics

An Environmental Systems Research Institute (ESRI) ArcView 3.2 Geographic Information System (GIS) project file resides in the top-level directory of this DVD. All associated GIS files are contained in subdirectories under the data directory. The user must have a copy of ESRI ArcView 3.2 or later in order to view the project files. Visit the ESRI Website (http://www.esri.com) for information concerning this and other software.

This project file (johnday.apr) contains a startup script which prompts the user for the drive letter of the DVD-ROM drive. This information is needed in order to establish "hotlinks" found within the project file. If the ArcView project file and the data directory are copied to the hard disk - maintaining the original directory hierarchy, then the location entered for the startup script should refer to the directory location of the ArcView project file. If for some reason the directory location is entered incorrectly, then the user can click on the pink button with the yellow CD () to reenter the information.

For those users who do not have ArcView 3.2 or later, the individual GIS data files can still be viewed with a compatible GIS viewer, or a free GIS viewer -ArcExplorer. This GIS data viewer is available from ESRI (http://www.esri.com). Please note that the ArcExplorer software is limited to the Microsoft Windows operating systems and some UNIX operating systems.

Custom Tool:
The ArcView project file (johnday.apr) has a special tool included which aids in the comparison between the sidescan-sonar mosaic and the 1966 aerial-photo mosaic. On the tool menu bar a button has been added () which links two view windows. This is actually a tool menu, and although not easily visible, there is a small black triangle in the lower right corner which allows access to the companion tool (). When the "bug" button is clicked, the user is prompted to select two views to "tie". A listbox with all of the views in the project pops up, and the user can then click on two views that they want to be linked together. Once this is done, the user selects the "bowtie" button and clicks in one of the selected views. A small red "x" graphic will be placed in the view at the click location, and the view will pan such that the "x" is in the center of the view. In the linked view, a small red "x" will be placed at the same coordinate location, and that view will not only pan such that the "x" is in the center of the view, but also zoom to the same scale as the first view. The view windows do not have to be the same size. This tool was developed to allow a quick and easy comparison of feature locations in two different views. This method was preferred to turning overlying features on and off in a single view. To change which two views are linked, simply select the "bug" button again, and select different views. If the "bowtie" button is selected and the user clicks in a view before the linked views have been defined, the user will be prompted to select the views to tie. The "x" placed in the views is a graphic and can be selected and deleted from the view at any time. This tool is also available as an extension on the ESRI Website on the ArcScripts download page (http://arcscripts.esri.com/), search for "Tie 2 Views".

Extensions:
The ArcView project file uses raster image files compressed with MrSid Geospatial Encoder version 1.4. In order to load and view these files, the MrSid Image Support extension must be loaded. This extension will be loaded by default within the project file.

The project file is also setup to "hotlink" to JPEG images. The JPEG (JFIF) Image Support extension must be loaded for this to work. As with the MrSid extension, this extension will be loaded by default within the project file.

Projection:
All of the shapefiles are in the Geographic NAD83 coordinate system. The georeferenced sidescan-sonar images are available in both the Geographic NAD83 coordinate system, and Washington State Plane South, NAD83 projection. Within the johnday.apr project file, the data loaded into the views are all in the Geographic NAD83 coordinate system.

Hotlinking:
The survey trackline data presented within the project files are "hotlinked" to JPEG images of the seismic-reflection profiles acquired on those lines. To view these images, click on the lightning bolt () within the project tool bar, and click on an individual trackline within the active trackline theme. The JPEG image of the seismic-reflection profile corresponding to that trackline will be opened in a separate view window so that the user can pan and zoom on the image.

The point shapefiles from the ground-truthing in 2000 and 2002 are also setup for hotlinking. Clicking on a point with the lightning bolt tool () will bring up a JPEG image of a bottom photograph from that location, or a location nearby.