Enhanced Grayscale TIFF Image of the 1-m Sidescan-Sonar Data From National Oceanic and Atmospheric Administration (NOAA) Survey H11251 Offshore of Rocky Point, New York (H11251_1MSSS_GEO.TIF, Geographic, WGS84)

The sidescan-sonar data were acquired with a Klein T-5000 sidescan-sonar system hull mounted to an 8.5-m aluminum launch deployed from the NOAA ship Thomas Jefferson. The system was set to sweep 100 m to either side of the launch tracks. The sonar systems emitted two (port and starboard) 50°-wide beams tilted down 20° from horizontal, and transmitted at 455 kHz. The data were acquired in XTF (extended Triton data format), recorded digitally through an ISIS data acquisition system, and processed using CARIS SIPS (Sidescan Image Processing) software for quality control, and to produce a composite sidescan-sonar image at 1-m horizontal resolution. As part of this process, the sidescan-sonar data were demultiplexed and filtered to remove speckle noise and correct for slant-range distortions. Image 'shine through', to account for areas of overlap, and auto-contrast adjustment were applied. Contrast enhancement based on the dynamic range of the data was applied to the mosaic and it was then projected into UTM Zone 18, NAD83 to produce the GeoTIFF.

The image was imported into Adobe Photoshop CS2 in order to apply a linear stretch (i.e., increase the dynamic range of the data), to change image from RGB to 8-bit grayscale, to invert the grayscale to make strong reflections light tones and weak reflections returns darker tones, and to correct tonal artifacts caused by improper cross-track normalization.

ArcToolbox - Data Management Tools - Projections and Transformations - Define Projection Tool was used to define projection at UTM Zone 18 NAD83 in ArcGIS 9.2.

The UTM sidescan-sonar image was projected from UTM Zone 18 NAD83 to geographic WGS 84 using transformation 1, bilinear resampling technique and default output cell size, in ArcGIS 9.2 with the ArcToolbox - Data Management Tools - Projections and Transformations - Raster - Project Raster Tool.

PhotoShop CS was used to convert the black border to white with the Paint Bucket tool and , and to assign a 'NO DATA' value (255).

Because saving a file in Photoshop CS2 removes the georeferencing information, GeoTIFFExamine was used to re-add the georeferencing information to the header of the image, making it a GeoTIFF.

ArcToolbox - Data Management Tools - Projections and Transformations - Define Projection Tool was used to define the projection as Geographic WGS84 in ArcGIS 9.2.

Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The source information was incomplete and had to be modified to meet the standard. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.

Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.

Added keywords section with USGS persistent identifier as theme keyword.