Data Management Plan

Raw XTF files. Sonar data were collected November 6 to December 15, 2009, in the estuary north from Saugerties to Troy. Data Collection and Processing: The interferometric system used to measure acoustic reflectivity, provided a quantitative measure of reflectivity for every square meter of the survey area. Fugro's system measured and recorded acoustic reflectivity that has a high dynamic range such that the full range of reflectivity's encountered in the estuary environment can be recorded while maintaining a constant gain setting on the system receiver. Reflectivity data from the GeoSwath was used to produce a normalized as well as a classified image of the bottom. Additionally, Fugro provided slope, aspect and hillshade models as additional acoustic parameters. Backscatter data processing was completed with CARIS 7.0. Raw XTF files were created by converting Hypack format (*.HSX) into Triton format (*.XTF) using Hypack 2009a.

Original contact information:

Contact Name: John Ladd

Contact Org: Hudson River National Estuarine Research Reserve, NYS DEC

Phone: 845-889-4745

Email: jxLadd@gw.dec.state.ny.us

Process Steps:

• 2010-01-01 00:00:00 - For seabed classification, the industry standard is to not change gains during a survey. Test lines were run to determine the optimum gain settings for the actual bottom backscatter values. Selected gain settings remained unchanged over the course of the project. The following parameters were used when collecting the data - GeoSwath Transmit Power = 2, GeoSwath Pulse Length = 2, GeoSwath SSS Frequency = 250kHZ
• 2010-01-01 00:00:00 - Using a data converter in Hypack 2009a (HSX2XTF), raw side scan sonar files were converted from Hypack's HSX format to Triton's XTF format.
• 2010-01-01 00:00:00 - For export of .tif files. Once the side scan was cleaned and edited, this non-normalized data was converted into a series of GeoTIFF mosaics. Mosaics are geographically referenced, and presented in one meter resolution. For ease of integration with previous benthic mapping products, all GeoTIFF images (including those listed below) were broken into panels coinciding with the boundaries and naming convention of the Hudson River Survey Index. With Caris 7.0 Mosaic Editor, the data was normalized by applying Auto TVG (Time-Varying Gain), which applies gains to individual pings, and AVG (Angle-Varying Gain) utilizing the Trend Method. AVG was used to normalize mean angular intensities with a moving average filter applied to a window of pings. According to Caris, the Trend Method defines how to weigh the samples when doing the AVG. Backscatter curves can usually be modeled with a line for those samples between 30 and 60 degrees from nadir. This method will do a line of best fit for data between 30 and 60 degrees and give a high weight to those samples that fit the line the closest. Samples outside this 30-60 degree range will all be weighted equally. Once side scan data was normalized, GeoBars (Geo-referenced Backscatter Raster) were created. From the GeoBars, the data were exported into GeoTIFF images portraying the normalized orthorectified mosaics in one meter resolution. On Charts 5a-5c, the normalized orthorectified mosaics created from the current sonar reflectivity dataset were laid over top of the data previously collected by SUNY.