CORSICA_CLRHSHD.TIF: Color-Hillshade Relief GeoTIFF Image of the Corsica River Estuary Area (UTM, Zone 18, NAD83)

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:


What does this data set describe?

Title:
CORSICA_CLRHSHD.TIF: Color-Hillshade Relief GeoTIFF Image of the Corsica River Estuary Area (UTM, Zone 18, NAD83)
Abstract:
Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine the importance of nutrient delivery to Chesapeake Bay via this pathway. Resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge from this primarily agricultural watershed that may be contributing to eutrophication, harmful algal blooms, and fish kills. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the estuary in April and May 2007. Techniques used included continuous resistivity profiling (CRP), piezometer sampling, seepage meter measurements, and collection of a radon tracer time series. Better understanding of the style, locations, and rates of groundwater discharge could lead to improved models and mitigation strategies for estuarine nutrient over-enrichment in the Corsica River Estuary, and other similar settings. More information on the field work can be accessed from the Woods Hole Coastal and Marine Science Center Field Activity webpage: <http://quashnet.er.usgs.gov/data/2007/07005/>
  1. How should this data set be cited?

    Cross, VeeAnn A. , 2011, CORSICA_CLRHSHD.TIF: Color-Hillshade Relief GeoTIFF Image of the Corsica River Estuary Area (UTM, Zone 18, NAD83): Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Bratton, John F. , Worley, Charles R. , Crusius, John, and Kroeger, Kevin D. , 2011, Continuous resistivity profiling data from the Corsica River Estuary, Maryland: Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -76.160718
    East_Bounding_Coordinate: -76.060537
    North_Bounding_Coordinate: 39.121622
    South_Bounding_Coordinate: 39.034459

  3. What does it look like?

    <https://pubs.usgs.gov/of/2010/1094/data/basemap/corsica_clrhshd.gif> (GIF)
    Thumbnail image of the color-hillshade relief image from the Corsica River Estuary area.

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2011
    Currentness_Reference: publication date

  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 319 x 285 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: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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 30.000000
      Ordinates (y-coordinates) are specified to the nearest 30.000000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    There are no attributes associated with the GeoTIFF image. Pixel values convey RGB values of individual cells. The shades of blue represent underwater bathymetry areas while the tans and greens are land elevation areas.


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?

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov


Why was the data set created?

The purpose of this dataset is to provide the color-hillshade relief image of the Corsica River Estuary area in GeoTIFF format (UTM zone 18, NAD83) that can be viewed by a variety of software programs.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: Nov-2009 (process 1 of 6)
    Output the colormap used with the elevation dataset from ArcMap 9.2. To do this, used VACExtras 2.1 - VACExtras - Raster - Import or Export to GMTraster legend. I selected the option to export, chose the combelev as the raster theme (with the legend displayed in the colors of choice as a classified legend), and output the results to the file corsical_elev.cpt. This process step and all subsequent process steps were carried out by the same person - VeeAnn A. Cross. The original elevation dataset and the metadata for how that grid was generated are available from the basemap section at <https://pubs.usgs.gov/of/2010/1094/html/catalog.html>.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

    Data sources used in this process:
    • combelev

    Data sources produced in this process:

    • corsical_elev.cpt

    Date: Nov-2009 (process 2 of 6)
    Used Mirone version 1.4.0 standalone software to read the binary grid (combelev). Loaded the color map using Image - Color Palettes - Change color palette. Then File - Read GMT Palette - Use Z-levels. At this point I can load the cpt file with the colormap information in it. Then used the Shaded Illumination button - GMT grdgradient - option 2 (Lambertian) and set the Azimuth to 315 and the Elevation to 30. And finally saved the image as a GeoTIFF - corsica_clrhshd.tif under File - Save Image as - GeoTIFF. This opens another window, in which I check the box "Preserve Image original size".

    Data sources used in this process:

    • combelev
    • corsical_elev.cpt

    Data sources produced in this process:

    • corsica_clrhshd.tif

    Date: Nov-2009 (process 3 of 6)
    Used GeoTIFFExamine to write the GeoTIFF header information to a TIFF world file.

    Data sources used in this process:

    • corsica_clrhshd.tif

    Data sources produced in this process:

    • corsica_clrhshd.tfw

    Date: Apr-2010 (process 4 of 6)
    Upon initial display in ArcMap 9.2, the colors weren't what were expected. So I opened the TIFF image in Adobe Photoshop CS3 and resaved the TIFF with no compression, Pixel Order interleaved, and IBM PC byte order. This seemed to resolve the color display issues.

    Data sources used in this process:

    • corsica_clrhshd.tif

    Data sources produced in this process:

    • corsica_clrhshd.tif

    Date: Apr-2010 (process 5 of 6)
    Using Photoshop to resave the TIFF image had the effect of deleting the spatial referencing information in the header of the file. So I used GeoTIFFExamine to read the world file information back into the header of the image making the image a GeoTIFF.

    Data sources used in this process:

    • corsica_clrhshd.tfw

    Data sources produced in this process:

    • corsica_clrhshd.tif

    Date: Apr-2010 (process 6 of 6)
    Then defined the projection using ArcMap 9.2 - ArcToolbox - Data Management Tools - Projections and Transformations - Define Projection. This creates the aux file that ArcGIS reads with the complete projection parameters. The tool parameters: input: corsica_clrhshd.tif; coordinate system: NAD_1983_UTM_Zone18N

    Data sources used in this process:

    • corsica_clrhshd.tif

    Data sources produced in this process:

    • corsica_clrhshd.aux

  3. What similar or related data should the user be aware of?

    Department of Commerce (DOC), National Oceanic and Atmospheric Adminis, 1998, Chesapeake Bay, VA/MD (M130) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA: NOAA's Ocean Service, Special Projects (SP), Silver Spring, MD.

    Online Links:

    U.S. Geological Survey (USGS), EROS Data Center, 1999, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.

    Online Links:

    NOAA Coastal Services Center Coastal Remote Sensing Program, 20070613, 2003 Maryland LIDAR mapping project.

    Online Links:

    Other_Citation_Details: Time period of content is 20030301 to 20031130


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

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    This image is a combination of three different datasets with three different horizontal accuracies. For the LIDAR data, the metadata reports the horizontal accuracy as "The horizontal coordinate values were designed to meet NSSDA accuracy for data at 1:2400 scale." The metadata for the NED elevation data does not specify a horizontal accuracy. The Chesapeake Estuarine bathymetry dataset metadata reports the horizontal accuracy as "The horizontal accuracy of the DEM is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the source soundings used to generate the DEM. As a first approximation the locational accuracy of the source soundings are 0.0015 m at source "Smooth Sheet" scale (120 m @ 1:80,000 to 15 m @ 1:10,000). Smooth Sheets are maps generated as a principle product of each (historic) hydrographic survey with fully corrected soundings plotted on them. Digital elevation models comply with the National Map Accuracy Standards (NMAS) accuracy requirements. The positional accuracy is estimated at 3 meters."

  3. How accurate are the heights or depths?

    This image is a combination of three different datasets with three different vertical accuracies. For the LIDAR data, the metadata reports the vertical accuracy as "The RMSE value of 14.3 cm at the 95% confidence level was determined by an independent accuracy assessment conducted by Dewberry LLC according to the contract specifications. These specifications followed FEMA Appendix A guidelines regarding assessing vertical accuracy. For data accurate to within 18.5 cm RMSE, the guidelines recommended a minimum of 20 independent check points be located in each of 5 different land cover categories: Grass/Ground, High Grass/Crops, Brush/Low Trees, Forest, and Urban/Pavement. A total of 125 points were used for the assessments. These points were surveyed by a licensed land surveyor and provided a positional location and elevation with an accuracy that exceeded the predicted accuracy of the LIDAR data. The entire accuracy reports can be found at <http://dnrweb.dnr.state.md.us/gis/data/lidar>. The RMSE value is 14.3 cm. See the Vertical Positional Accuracy Report section for more information." The metadata for the NED elevation data does not specify a vertical accuracy. The Chesapeake Estuarine bathymetry dataset metadata reports the vertical accuracy as "The vertical RMSE statistic is used to describe the vertical accuracy of a DEM. It encompasses both random and systematic errors introduced during production of the data. The RMSE is encoded in element number 5 of record C of the DEM. This accuracy estimate includes components related to quantization of the source soundings (1.3 to 0.15 m), the systematic editing of the source data (1percentor 0.10m), un-sampled bathymetric features (estimated at less than 5percentof depth), time related changes (erosion, deposition, and seismic shifts), and dredging operations (cut and fill). It is estimated that the accuracy of the Bathymetric DEMs is 2 percent of depth or 1 meter for depths grater than 20 meters and 2 percent of depth or 0.20 meters for depths shallower than 20 meters. THESE DEMs SHOULD NOT BE USED FOR NAVIGATION. There are three types of DEM vertical errors: blunder, systematic, and random. These errors are reduced in magnitude by editing but cannot be completely eliminated. Blunders are errors of major proportions and are easily identified and removed during interactive editing. Systematic errors follow some fixed pattern and are introduced by data collection procedures and systems. Systematic error artifacts include vertical unsampled elevation shifts, relative spacing of the source soundings, misinterpretation of terrain surface caused by softness or poor reflectivity and by the resolution of the collected soundings (feet, feet and fractions, fathoms, fathoms and fractions, meters, tenths of meters etc.). Random errors result from unknown or accidental causes. The 1 degree (DSQ) DEMs are generated from 30 m grids on UTM projection. The RMSE difference between these surfaces is an estimate of the vertical accuracy of the DSQ DEMs."

  4. Where are the gaps in the data? What is missing?

    This dataset represents the complete elevation information for the area of interest in GeoTIFF format.

  5. How consistent are the relationships among the observations, including topology?

    The individual datasets making up this combined dataset were not scrutinized for errors.


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:
The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey and the National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS) as the originators of the individual datasets. These data are not to be used for navigation.

  1. Who distributes the data set? (Distributor 1 of 1)

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  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 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.

  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 WinZip contains a GeoTIFF image and an accompanying world file. The user must have software capable of uncompressing the WinZip file. To simply view the image, any software capable of reading a TIFF file is sufficient. To view the image in its geospatial location, the user must have software that is either capable of reading the header information in the GeoTIFF, or alternatively reading the registration information in the TIFF world file.


Who wrote the metadata?

Dates:
Last modified: 07-Mar-2011
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Generated by mp version 2.9.6 on Mon Mar 07 14:04:26 2011