1-meter per pixel sidescan-sonar mosaic collected in Moultonborough Bay, Lake Winnipesaukee, New Hampshire by the U.S. Geological Survey in 2005 (GeoTIFF, UTM Zone 19N, WGS 84, WINNI_SONAR.TIF)

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Frequently anticipated questions:


What does this data set describe?

Title:
1-meter per pixel sidescan-sonar mosaic collected in Moultonborough Bay, Lake Winnipesaukee, New Hampshire by the U.S. Geological Survey in 2005 (GeoTIFF, UTM Zone 19N, WGS 84, WINNI_SONAR.TIF)
Abstract:
In freshwater bodies of New Hampshire, the most problematic aquatic invasive plant species is Myriophyllum heterophyllum or variable leaf water-milfoil. Once established, variable leaf water-milfoil forms dense beds that can alter the limnologic characteristics of a waterbody, impacting natural lacustrine communities and their habitats. Variable leaf water-milfoil infestations also disrupt recreational uses of waterbodies and have negatively affected swimming, boating, fishing, and property values in and around several lakes and ponds in New Hampshire.
In 1965, Moultonborough Bay, Lake Winnipesaukee became the first waterbody in New Hampshire where variable leaf water-milfoil was observed. Variable leaf water-milfoil is native to the Southeastern and Midwestern areas of the United States where more alkaline waters appear to limit the growth of this plant. Outside its native range, however, it adapts well to the relatively acidic, low-alkalinity, and nutrient-poor conditions of oligotrophic lakes and bays similar to Moultonborough Bay.
In 2005, the New Hampshire Department of Environmental Services (NHDES) collaborated with the U.S. Geological Survey to investigate the distribution (presence and density) of variable leaf water-milfoil in Moultonborough Bay. This study utilized geophysical systems and conventional water-quality measurements to identify lake-floor environments that may provide suitable habitat for the establishment and growth of variable leaf water-milfoil. The results of the study are intended to assist resource managers in federal and state agencies by providing methods for detecting variable leaf water-milfoil and for identifying areas susceptible to infestation. Ultimately, this information may lead to early detection, prevention, and more effective mitigation strategies.
Field activity information for this cruise is available on-line through the U.S. Geological Survey Coastal and Marine Geoscience Data System https://cmgds.marine.usgs.gov/fan_info.php?fa=2005-004-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 2014, 1-meter per pixel sidescan-sonar mosaic collected in Moultonborough Bay, Lake Winnipesaukee, New Hampshire by the U.S. Geological Survey in 2005 (GeoTIFF, UTM Zone 19N, WGS 84, WINNI_SONAR.TIF): data release DOI:10.5066/F71N7Z4H, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Denny, J.F., Danforth, W.W., Worley, C.R., and Irwin, B.J., 2014, High-resolution geophysical and sample data collected in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005, USGS Field Activity 2005-004-FA: data release DOI:10.5066/F71N7Z4H, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.395192
    East_Bounding_Coordinate: -71.353088
    North_Bounding_Coordinate: 43.731992
    South_Bounding_Coordinate: 43.701454
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2005-004-FA/data/backscatter/winni_sonarsm.jpg (JPEG)
    Grey scale image of sidescan-sonar mosaic for Moultonborough Bay, Lake Winnipesaukee
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 26-Jul-2005Currentness_Reference: ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: remote-sensing image
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 3300 x 3300 x 1, type Pixel
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    There are no attributes associated with a GeoTIFF image. Image pixel values contain acoustic reflectivity values normalized to an 8-bit data range (0-255) with the data range 0-254. Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). The background color is set to 255 and can be turned off without removing data values.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x 2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

Why was the data set created?

This sonar mosaic was generated from Klein 3000 sidescan-sonar data collected by the U.S. Geological Survey during USGS field activity 2005-004-FA within Moultonborough Bay, Lake Winnipesaukee, New Hampshire. These data are used to define the lake floor sediment distribution within Moultonborough Bay. The sonar data will be correlated to sediment samples, bottom video and photographs collected in the bay in order to interpret the acoustic facies.

How was the data set created?

  1. From what previous works were the data drawn?
    none (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw backscatter data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Data were acquired with an L3-Klein Associates 3000 digital, dual-frequency, sidescan-sonar (www.l-3klein.com). Dual frequencies are nominally 100 (132 kHz) and 500 (445 kHz) kHz. The sidescan-sonar was towed aft the R/V Rafael. Line spacing was 50-meters throughout the survey area. Data files were recorded with SonarPro (2005) in XTF (extended-Triton Format) format at a 0.03-sec ping rate yielding a 50-meter range (100-meter swath). The 100 kHz data were used to generate the sidescan-sonar mosaic. The data range within the sidescan-sonar mosaic (digital number values (DN) of the 8-bit image) is 0 - 254, with the background value (i.e. No DATA) set to 255.
  2. How were the data generated, processed, and modified?
    Date: 2005 (process 1 of 6)
    XSonar/ShowImage sidescan-sonar processing software was used to process the raw XTF sonar data following the methodology of Danforth, (1997). A 4 across track x 3 along track pixel median filter was applied to the raw sidescan-sonar data to remove speckle noise and a normalization of 4095 was applied to adjust the dynamic range within the output processed file. Processed data are stored as 8-bit. Navigation were also extracted from the raw data at 2-minute intervals and saved in an ASCII file. Quality checks were conducted on the navigation to eliminate spurious or duplicate navigation fixes. The sonar data were further processed to correct for towfish altitude (i.e. proper tracking of the lakefloor), and slant-range and beam pattern distortions inherent in the sonar data. Processed sonar files were then merged with the edited navigation. Processed sonar files were then mapped at a 1-meter resolution in UTM coordinates (UTM, Zone 19N, WGS 84, meters) and saved in two XSonar/ShowImage mosaic files representing odd and even (i.e. every other line) sonar tracklines, or files.
    Below are the typical parameters for processing with XSonar: File Type: XTF, Low Frequency (132 kHz)
    Setup Option: Navigation= Lat/Lon, Navigation Interval= 2 minute
    Demultiplexing Range and Filter options: Across track=4 (pixels), Along track= 3 (pixels), Port/Starboard Normalize = 4095 (default), Port High Pass: 65535 (default,) Input= 16 bit, Normalize Image= yes.
    Beam Pattern Correction options: Number of lines= 100, Ping overlap=50, Max beam angle= 90 (default), Response angle=55 (default), Data normalization (0-255)=1 (default), Port/Stbd Tone Adjustment= "on" and "Normal"
    Jane F. Denny performed this and all subsequent process steps. Person who carried out this activity:
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2311 (voice)
    508-57-2310 (FAX)
    jdenny@usgs.gov
    Date: 2005 (process 2 of 6)
    The Unix Portable Bitmap Format (PBM) utilities, rawtopgm and pnmtotiff, were used to extract the 80-byte header from the XSonar/ShowImage odd and even mosaic files and convert the raw raster image to a TIFF image file. (rawtopgm -headership 80 #xpixel #ypixel *.ras | pnmtotiff - > *.tif)
    Date: 2005 (process 3 of 6)
    The odd and even TIFF images were then imported into PCI Geomatica Software and digitally mosaicked at a 1-meter pixel resolution using PCI's OrthoEngine based on the procedures described in Paskevich (1996). The composite mosaic was registered in the UTM (Zone 19N, WGS84, meters) coordinate system and exported as a GeoTIFF image.
    A TIFF World File (TFW) was created using Mentor Software GeoTiffExamine (no version) to define the spatial extent of the TIFF image. GeoTiffExamine was also used to transfer the spatial information to the TIFF, creating a GeoTIFF image
    Date: 2013 (process 4 of 6)
    The GeoTIFF image was then imported to Adobe Photoshop CS3 in order to adjust the 8-bit range of the image file, so that areas of no data (i.e. the background) are represented by a pixel value of 255 and areas of data range from pixel values of 0 to 254.
    Date: 2013 (process 5 of 6)
    After editing the data range and saving the TIFF image, the header information was not saved. A world file (tfw) was created with a text editor. GeoTiffExamine was used to generate a GeoTIFF from the world file (tfw).
    Date: 06-Apr-2017 (process 6 of 6)
    The online links to the data were updated to reflect the new server hosting the data. Additionally, other small edits could be made to the metadata, such as modifying http to https where appropriate. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Argue, Denise M., Kiah, Richard G., Denny, Jane F., Deacon, Jeffrey R., Danforth, William W., Johnston, Craig M., and Smagula, Amy P., 2007, Relation of Lake-Floor Characteristics to the Distribution of Variable Leaf Water-Milfoil in Moultonborough Bay, Lake Winnipesaukee, New Hampshire, 2005: Scientific Investigations Report 2007-5125, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Danforth, William W., 1997, XSonar/ShowImage: A complete system for rapid sidescan-sonar processing and display.: Open-File Report 97-686, U.S. Geological Survey, Reston, VA.

    Online Links:

    Paskevich, Valerie, 1996, MAPIT: An improved method for mapping digital sidescan sonar data using the Woods Hole Image Processing System (WHIPS) Software: Open-File Report 96-281, U.S. Geological Survey, Reston, VA.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Image pixel values contain acoustic reflectivity values normalized to an 8-bit data range (0-254). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). The nodata value is 255.
  2. How accurate are the geographic locations?
    Navigation was acquired with Wide Area Augmentation System ( WAAS), which is accurate to + or - 1 to 2 meters, horizontally. Navigation data were acquired with a LGBX Pro receiver and sent directly to the sidescan-sonar acquisition software, L3-Klein Associates, SonarPro. The LGBX Pro received WAAS positions from an antenna located on the port, aft roof of the cabin. The sidescan-sonar towfish was towed at a shallow depth, close to the lake surface due to the shallow waters of the survey area. Layback was measured upon deployment of the towfish. During data processing, layback was found to be negligible due to the shallow-tow of the vehicle. No significant offset of features was observed when mosaicking adjacent lines of sonar data. The following offsets are measured prior to deployment of the sidescan-sonar towfish and entered into SonarPro: height of the block, offset from DGPS (WAAS) antenna to the block, and height of the DGPS antenna above the waterline. Considering errors in measuring towfish layback, as well as accuracy of WAAS, horizontal accuracy of the sidescan-sonar data are conservatively assumed to be + or - 10 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Lines 43 - 112 were used to generate the final GeoTIFF mosaic. Gaps present in this data are generally in shallow-water areas where the system was not tracking bottom, or poor quality sonar returns precluded use in the completed mosaic. Additionally, some lines were very noisy (e.g. l110f1) and were not included in the final mosaic.
  5. How consistent are the relationships among the observations, including topology?
    This image represents sidescan-sonar backscatter data collected within Moultonborough Bay, Lake Winnipesaukee, New Hampshire. Gaps generally occur in nearshore areas too shallow to successfully maneuver the R/V Rafael.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
  2. What's the catalog number I need to order this data set? The winni_sonar.zip file contains the GeoTIFF image winni_sonar.tif and the associated TIFF world file winni_sonar.tfw. In addition to the image and world file, the zip file also contains the browse graphic (winni_sonarsm.jpg) and the FGDC CSDGM metadata in the following formats: XML, HTML, FAQ and text.
  3. What legal disclaimers am I supposed to read?
    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 U.S. Geological Survey 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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    This zip file contains a GeoTIFF image with an accompanying world file. To utilize these data, the user must have an image viewer, image processing or GIS software package capable of importing a GeoTIFF image. A free spatial data viewer, ArcGIS Explorer, capable of displaying the data is available from Esri at www.esri.com. The zip file also contains associated metadata.

Who wrote the metadata?

Dates:
Last modified: 06-Apr-2017
Metadata author:
Jane F. Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, Massachusetts
USA

508-548-8700 x2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.36 on Thu Apr 06 12:54:53 2017