U.S. Geological Survey Data Series 647
Two versions of navigation maps are provided in this Data Series. The first consists of a trackline map, which represents the vessel position during the survey, since the navigation data used to create this map have not been corrected for the offset between the GPS antenna and the boomer's transducer (figure 1). The trackline map was created with ESRI ArcGIS 10 software, exported to Adobe Illustrator for further editing, and saved in JPEG format. This image can be accessed through the link provided below or from within the cruisenav folder. For more information about the GIS project, refer to the Software page. The second set of included maps is individual line navigation maps. With these maps, the GPS offset has been applied, so the location of the boomer shotpoint is therefore shown.
The line navigation maps, which have been corrected for the GPS offset mentioned above, were created with CTI SonarWeb software and are stored in the linenav folder. Refer to the Profiles page for more information about the geospatial and printable profiles.
In addition to shotpoint navigation files, 500-shot-interval files were generated to help correlate shot locations on the map with evenly spaced 500-shot index markers along the top of the printable profile images. Both shotpoint navigation files and 500-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software via the readll script (located in boomll.tar, which can be found in the su folder). Shotpoint coordinates were then projected from latitude and longitude coordinates to UTM northings and eastings (WGS84, Zone 17, meters) using PROJ.4 software (http://trac.osgeo.org/proj/) and reformatted for use with ESRI GIS software. The processed navigation data have not been corrected for the offsets between the shotpoint and GPS antenna (fig. 1).
The processed shotpoint navigation and 500-shot-interval location files can be accessed through the links provided below or from within the nav folder. Each ASCII text file contains eight fields separated by commas and defined as follows:
Field 1: UTM X (Zone 17)
Field 2: UTM Y (Zone 17)
Field 3: Trackline Number
Field 4: Shotpoint Number
Field 5: Longitude (decimal degrees)
Field 6: Latitude (decimal degrees)
Field 7: Year
Field 8: Day of Year:Hour:Minute:Second (UTC)
05fgs01.txt - Processed Shotpoint Navigation (21-KB ASCII text file)
s05fgs01.txt - Processed 500-Shot-Interval Location Navigation (41-KB ASCII text file)
Shotpoint navigation files were extracted from the trace headers of each line using Seismic Unix software. Unprocessed navigation files are stored as ASCII text files in the rawnav folder by trackline number. These navigation data have not been corrected for the offset between the shotpoint and GPS antenna. Each file contains six fields separated by a space and defined as follows:
Field 1: Trackline Number
Field 2: Shotpoint Number
Field 3: Longitude (decimal degrees)
Field 4: Latitude (decimal degrees)
Field 5: Year
Field 6: Day of Year:Hour:Minute:Second (UTC)
