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This data release makes multibeam echosounder data from the 1998 survey of the sea floor southwest of Montauk Point, New York, available in digital form. The GeoTIFF image of backscatter intensity provides qualitative information on the sediment texture and roughness of the sea floor. Backscatter intensity, a measure of the strength of the acoustic return from the sea floor, is a function of the properties of the surficial sediments and of the bottom roughness. Generally high backscatter intensity (strong return), shown as light gray tones, is associated with rock or coarse-grained sediment, and low backscatter intensity (weak return), shown as dark gray tones, with fine-grained sediments.
1. Create a blank 8 bit map file:
Command line: make_blank mosaic_file
This command commences a dialog to enable an 8 bit image and input the map boundaries and resolution. The program also prompts for the projection type and parameters to be used creating the binary map file (custom Mercator projection, central longitude of -75 degrees, latitude of true scale 40 degrees north). Then the "blank" file is copied to two files required by the mosaic program:
Command line: cp mosaic_file.blank mosaic_file.mos
Command line: cp mosaic_file.blank mosaic_file.ran
2. Create backscatter files that can be then mosaicked from the backscatter time series:
Command line: getBeamPattern filename (prefix only)
Command line: makess -pixel 1.0 -beam_patt beampatt filename (prefix only) output.ss
Command line: glfill output.ss output.ss_fill (fills in data dropouts).
3. Mosaic all the backscatter files created in the last step (for each output.ss_fill). Command line: mos2 -autoseam -maxazi 10 -maxdist 10 mosaic_file output.ss_fill
4. Use a two-point linear contrast stretch (0-254; 255 is no data) to enhance the shaded-relief image:
Command line: stretchacres -low 170 -high 210 -in mosaic_file -out mosaic_file.stretch Person who carried out this activity:
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Are there legal restrictions on access or use of the data?Access_Constraints: None
Use_Constraints: None
Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Data format: | GeoTIFF image of backscatter intensity and associated metadata from a multibeam survey southwest of Montauk Point, New York, compressed in a WinZip (version 14) file in format GeoTIFF (version ArcGIS 9.3) GeoTIFF image Size: 1.6 |
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Network links: |
https://www.sciencebase.gov/catalog/file/get/56cdc939e4b0b1892d9f0c31?name=mont_backi3m.zip https://doi.org/10.5066/F7Z899GG |
The GeoTIFF image of backscatter intensity is compressed into a WinZip (version 14) file (mont_backi3m.zip). To use these data, the user must have software capable of uncompressing the zip file and ArcGIS or another GIS application package capable of viewing the data.