Gypsy Moth Defoliation - 2003
GIS FAQs

gypmoth2003

Metadata also available as

Frequently-anticipated questions:

What does this data set describe?

  • Title: gypmoth_2003
  • Abstract: This dataset includes polygons of tree defoliation caused by gypsy moth caterpillars. They are delimited annually on 1:100,000 scale maps by aerial observers in small aircraft from altitudes of 1000 to 1500 feet above ground level. Data for this layer were collected 6/03.
  • Supplemental_Information: All defoliation mapped during this survey was moderate to heavy.
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
    • West_Bounding_Coordinate: -79.976489
    • East_Bounding_Coordinate:-77.919725
    • North_Bounding_Coordinate: 39.073431
    • South_Bounding_Coordinate: 37.404815
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    • Calendar_Date: June 2003
    • Currentness_Reference: ground condition
  5. What is the general form of this data set?
    • Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      • This is a Vector data set. It contains the following vector data types (SDTS terminology): G-polygon (200)
    2. What coordinate system is used to represent geographic features?
      • The map projection used is Lambert Conformal Conic.
        • Projection parameters:
          • Standard_Parallel:37.000000
          • Standard_Parallel:39.500000
          • Longitude_of_Central_Meridian:-79.500000
          • Latitude_of_Projection_Origin:36.000000
          • False_Easting:0.000000
          • False_Northing:0.000000
      • Planar coordinates are encoded using coordinate pair
        • Abscissae (x-coordinates) are specified to the nearest 0.000512
        • Ordinates (y-coordinates) are specified to the nearest 0.000512
        • 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?
    • gypmoth_2003 2003 Gypsy Moth Defoliation
    • FID Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    • Shape Feature geometry. (Source: ESRI) Coordinates defining the features.
    • AREA Polygon Area in square meters
    • ACRES Polygon area in acres
    • COUNTY County within which defoliation poly was mapped

Who produced the data set?

  1. Who are the originators of the data set?(may include formal authors, digital compilers, and editors)
    • Virginia Department of Forestry
  2. Who also contributed to the data set?

    Sketch Mapping was performed by Mike Griffin and Tim Tigner, Pilot was Phil Carpenter. Jason Braunstein digitized the sketch maps.

  3. To whom should users address questions about the data?
    • Jason Braunstein
      Virginia Department of Forestry
      GIS Manager
      900 Natural Resources Drive, Suite 800
      Charlottesville, VA 22903
      434.977.6555 (voice)
      434.296.2369 (FAX)

Why was the data set created?

Defoliation maps are used to evaluate the efficacy of insect suppression efforts, to guide the location of ground surveys, to inform localities of pest population status and trends, and to help analyze spatial patterns and trends.

How was the data set created?

  1. From what previous works were the data drawn?
    • (source 1 of 1)
    • Source_Scale_Denominator: 100000
  2. How were the data generated, processed, and modified?
    • (process 1 of 1)
      • Metadata imported.
    • Data sources used in this process:
      • D:\TEMP\xml6C.tmp

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?
    • +/- 170 feet
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?

    Many errors are inherent in aerial sketchmapping. Observers vary greatly in experience and in tendency to divide or combine contiguous polygons. Light, weather conditions and terrain have considerable influence on what can be seen and how accurately it can be located. Different agents can cause the same or similar signature. Mapping must begin before defoliation is complete because refoliation quickly follows; the first areas to be mapped tend to be underrepresented. Light defoliation is not distinct enough to delimit. Small, isolated patches of defoliation are easily overlooked. Attributes recorded can vary with changes in conditions and information needed.

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

How can someone get a copy of the data set?

  • Are there legal restrictions on access or use of the data?
    • Access_Constraints: Data are available to all interested parties
    • Use_Constraints: Data are only to be redistributed with accompanying metadata
  1. Who distributes the data set?
    • [Distributor contact information not provided.]
  2. What's the catalog number I need to order this data set?
    • Downloadable Data
  3. What legal disclaimers am I supposed to read?

    This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user.

    While the Virginia Department of Forestry (DOF) has attempted to ensure that this documentation is accurate and reliable, DOF does not assume liability for any damages caused by inaccuracies in these data or documentation, or as a result of the failure of the data or software to function in a particular manner. DOF makes no warranty, express or implied, as to the accuracy, completeness, or utility of this information, nor does the fact of distribution constitute a warranty.

  4. How can I download or order the data?
    • Availability in digital form:
      • Data format:
      • Size: 0.081
    • Cost to order the data:

Who wrote the metadata?

  • Dates: Last modified: 09-Oct-2003
  • Metadata author:
    • Jason Braunstein
      Virginia Department of Forestry
      GIS Manager
      900 Natural Resources Drive, Suite 800
      Charlottesville, VA 22903
      434.977.6555 (voice)
      434.296.2369 (FAX)
  • Metadata standard: FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
  • Metadata extensions used:

Generated by mp version 2.7.3 on Thu Oct 09 13:49:32 2003