Publication_Place: U.S. Geological Survey, Woods Hole, MA
Publisher: USGS Coastal and Marine Geology Team
Description:
Abstract:
This ArcView GIS layer is a 25 m version of the completed SeaMARC 1A sidescan
sonar mosaic.
Purpose:
This GIS overlay is a component of the U. S Geological Survey, Woods Hole
Field Center's, Gulf of Mexico ArcView GIS database. The Gulf of Mexico
GIS database is intended to organize and display USGS held data and provide
on-line (WWW) access to the data and/or metadata.
Supplemental_Information:
Two sets images of the 25 m SeaMARC1A sidescan sonar data are available
for the study area. One image set has been radiometrically enhanced for
better viewing, and the other set has not been enhanced. This set is available
for user's who wish to apply their own enhancements. Additionally, the
images are available in both GEOTIFF and JPEG formats.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19900325
Ending_Date: 19900408
Currentness_Reference: data collection
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -86.6027
East_Bounding_Coordinate: -84.9864
North_Bounding_Coordinate: 26.9
South_Bounding_Coordinate: 26.1001
Keywords:
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: Woods Hole Field Center
Theme_Keyword: Gulf of Mexico database
Theme_Keyword: Exclusive Economic Zone
Theme_Keyword: EEZ
Theme_Keyword: sidescan sonar
Theme_Keyword: sidescan sonar mosaic
Theme_Keyword: composite mosaic
Theme_Keyword: TIFF
Theme_Keyword: TIF
Theme_Keyword: JPG
Theme_Keyword: Geotiff
Theme_Keyword: GEOTIFF
Theme_Keyword: SeaMARC 1A
Theme_Keyword: seamarc
Place:
Place_Keyword_Thesaurus: General
Place_Keyword: Gulf of Mexico
Place_Keyword: U.S. EEZ
Place_Keyword: U.S. Exclusive Economic Zone
Place_Keyword: Mississippi Fan
Access_Constraints: None
Use_Constraints:
Although this derived data set and it's lineage dataset have been used
by the USGS, no warranty, expressed or implied, is made by the USGS as
to the accuracy of the data and/or related materials. The act of distribution
shall not constitute any such warranty, and no responsibility is assumed
by the USGS in the use of these data or related materials.
The U.S. Geological Survey must be referenced as the originator of the
dataset in any future products or research derived from these data.
Publisher: Coastal and Marine Geology Team, Woods Hole, MA
Type_of_Source_Media: magnetic tape
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19900325
Ending_Date: 19900408
Source_Currentness_Reference: data collection
Source_Citation_Abbreviation: QMIPS data tapes
Source_Contribution:
SeaMARC 1A sidescan sonar data was collected using the QMIPS data acquisition
system and recorded to 8mm digital tape for post-cruise processing.
Process_Step:
Process_Description:
The individual SeaMARC 1A sidescan swaths were transferred from tape to
disk. The files were subsequently converted from the QMIPS format to a
WHIPS format for processing.
Source_Used_Citation_Abbreviation: QMIPS data tapes
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: WHIPS data files
The individual individual swath files were processed using the Woods Hole
Image Processing Software (WHIPS). The individual strips were processed
to apply geometric (i.e. slant-to-ground range corrections) and radiometric
corrections (i.e. beam correction shading).
Source_Used_Citation_Abbreviation: WHIPS data files
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: WHIPS data files
The SeaMARC 1A files that comprised the eastern half of the survey were
transferred to the Woods Hole Field Center's MicroVAX-II computer system.
This portion of the survey consisted of mostly straight line segments and
were to be digitally mosaicked on this system. (The western portion were
done a few months later with developing software). The MicroVAX-II computer
system contained the Mini-Image Processing System (MIPS) software that
was needed to map and digitally mosaic the data. To begin processing, the
WHIPS data files were all converted to MIPS format.
Source_Used_Citation_Abbreviation: WHIPS data files
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: MIPS data files
As the individual swaths were mapped, they were geo-referenced to the base
image, stenciled and mosaiced to the base. (The base was one swath that
had been mapped and was selected as the master which everything would be
registered with.) Control points were selected interactively to match features
on the adjacent lines and a rubber sheeting procedures were applied to
the mapped swaths to better align the images. Once registered, a stencil
line was interactively drawn around the area of the line to be added. This
stencil area was critical as it not only eliminated the unwanted area that
was overlapping the adjacent lines but defined the area to be kept. Finally
the registered, transformed and stenciled image was added to the base.
These steps were repeated for each swath until the eastern mosaic was completed.
Source_Used_Citation_Abbreviation: MIPS data files
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: MIPS data files
The SeaMARC 1A files that comprised the western half of the survey were
mapped using the WHIPS software. This area of the survey consisted of several
survey line segments. This software could handle curved line segments.
The files were projected and mapped with a Mercator project and a Clarke
1866 spheroid to match the eastern portion.
Source_Used_Citation_Abbreviation: WHIPS data files
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: WHIPS data files
The WHIPS mapped swaths were transferred to the Center's MicroVAX-II computer
system for stenciling and mosaicking with the MIPS software. Once transferred
to the MicroVAX, the files were converted to the MIPS format for processing.
Source_Used_Citation_Abbreviation: WHIPS data files
Process_Date: Unknown
Source_Produced_Citation_Abbreviation: MIPS data files
The converted WHIPS mapped swaths were stenciled and mosaicked with the
MIPS software. This procedure is similar to the one outlined for the eastern
portion of the survey. Control points were selected interactively to match
features on the adjacent lines and a rubber sheeting procedures were applied
to the mapped swaths to better align the images. Once registered, a stencil
line was interactively drawn around the area of the line to be added. This
stencil area was critical as it not only eliminated the unwanted area that
was overlapping the adjacent lines but defined the area to be kept. Finally
the registered, transformed and stenciled image was added to the base.
These steps were repeated for each swath until the western mosaic was completed.
Source_Used_Citation_Abbreviation: MIPS data files
The MIPS created mosaic, compos.pic, was transferred to a UNIX computer
system. The image was imported into a PCI Remote Sensing database file
and georeferenced as Mercator.
Using the PCI Remote Sensing software, a linear contrast stretch was applied
to the SeaMARC 1A sidescan sonar mosaic stored in channel 1. This was done
to improve the image's viewing by expanding the data's dynamic range.
The completed, enhanced, 25 m SeaMARC 1A sidescan sonar mosaic was exported
from the PCI 'pix' database as a GEOTIFF image with an associated ARC "world"
file.
The completed, enhanced, 25 m SeaMARC 1A sidescan sonar mosaic was exported
from the PCI 'pix' database as a JPEG image with an associated ARC "world"
file.
The completed, unenhanced, 25 m SeaMARC 1A sidescan sonar mosaic was exported
from the PCI 'pix' database as a GEOTIFF image with an associated ARC "world"
file.
The completed, unehanced, 25 m SeaMARC 1A sidescan sonar mosaic was exported
from the PCI 'pix' database as a JPEG image with an associated ARC "world"
file.
Although this derived data set and it's lineage dataset have been used
by the USGS, no warranty, expressed or implied, is made by the USGS as
to the accuracy of the data and/or related materials. The act of distribution
shall not constitute any such warranty, and no responsibility is assumed
by the USGS in the use of these data or related materials.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: TIFF
File_Decompression_Technique: No compression applied
Transfer_Size: 21847KB
Digital_Transfer_Option:
Offline_Option:
Offline_Media: CD-ROM
Recording_Capacity:
Recording_Density: 650
Recording_Density_Units: Mbytes
Recording_Format: ISO 9600
Compatibility_Information:
The user must have a system with a CD-ROM capable of reading an ISO-9660
standard CD-ROM disk. To browse the information contained on this disk,
the user must also have a current version of WWW browser available.
Digital_Form:
Digital_Transfer_Information:
Format_Name: JPEG
File_Decompression_Technique: No compression applied
Transfer_Size: 1331KB
Digital_Transfer_Option:
Offline_Option:
Offline_Media: CD-ROM
Recording_Capacity:
Recording_Density: 650
Recording_Density_Units: Kbytes
Recording_Format: ISO 9600
Compatibility_Information:
The user must have a system with a CD-ROM capable of reading an ISO-9660
standard CD-ROM disk. To browse the information contained on this disk,
the user must also have a current version of WWW browser available.
Fees: none
Technical_Prerequisites:
An image viewer, image processing or GIS software package capable of importing
a GEOTIFF or JPEG format file. If the georeferencing information cannot
be imported, the user may wish to obtain the georeferencing information
contained in a separate file, seamarc.txt, in the imagery/raw/georep or
imagery/enhanced/georep directory.
Access to the data and information contained on this CD-ROM was developed
using the HyperText Markup Language (HTML) utilized by the World Wide Web
(WWW) project. Development of the CD-ROM documentation and user interface
in HTML allows a use to access the information by using a variety of WWW
information browsers to facilitate browsing and locating information and
data.
This CD-ROM should be readable by a variety of operating systems including
Windows 95/98/NT, Macintosh and UNIX
