SWATHplus acquisition software (version 3.05.90) was used to digitally log the bathymetric data at a rate of 30 pings/second and 3,072 samples per swath (ping) in the SWATHplus SXR format. Data collection parameters are saved into a SWATHplus session file in SEA's SXS format. These files can be later used for data replay.
An Octopus F180R Attitude and Positioning system (see: <http://www.codaoctopus.com/motion/f180/index.asp>) recorded ship motion (heave, pitch, roll, and yaw). These data were transmitted via network connection to the SWATHplus data collection software. The Octopus F180R Inertial Measurement Unit (IMU) was mounted directly above the SWATHplus transducers, to minimize lever arm offsets that can lead to positioning errors. The F180R uses two L1 antennas for position and heading accuracy. The antennas are mounted on a rigid horizontal pole, 3 meters above the F180R IMU, with a horizontal separation of 1 meter and are offset from the IMU in a forward/aft configuration. The forward offset of the primary antenna from the IMU is 0.5 meters, with no port/starboard offset.
Eight sound-velocity profiles were acquired during survey operations at roughly 4-hr intervals using an Applied Microsystems SV Plus V2 Velocimeter (Applied Microsystems, 2008).
SwathEd (no version)
Xsonar/Showimage (no version)
-Create Blank Map Sheet at 0.5 meter resolution, UTM meters, Zone 17N, WGS84 (make_blank -prime 255 -8bit mosaic) -Copy mosaic.blank to mosaic.mos mosaic.ran -Mosaic the individual sonar lines (mos2 -maxdist 10 -custom_weight MOS_weights mosaic *.slr) -Remove the 1024 byte header from the mosaic.mos file (dd if=mosaic.mos of=mosaic.raw bs=1024 skip =1) -Convert the raw mosaic file to TIFF using Adobe Photoshop (CS3 10.0.1) -A world file was generated for the TIFF image using the UNIX command vi -GeoTIFF Examine, v. 1.01 (www.mentorsoftwareinc.com) was used to convert the TIFF image to a GeoTIFF.
Adobe Photoshop CS3 was used to apply a linear stretch to the backscatter mosaic. The data range (digital numbers) is 0 to 234; no data are represented by 255.
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