These contours are represented as vector data (lines). Each contour line is associated with an elevation (number of feet above sea level) in the attribute database. Contours were generated from the TIN (see description under DTM on page 6 of the supplemental METADATA FILE). Note that these contours are suitable for general landscape planning and educational purposes only. They are not survey-grade quality, and are not intended to support applications that require survey-quality data. These contours should be used for general reference and educational purposes only. The contour interval is 20 feet for counties/localities that lie west of the fall line (I-95 corridor) and 10 feet for localities that lie east of the fall line (I-95). The supplemental METADATA file included with the data contains an illustration below the Contour section that shows contours (left) and contours draped over aerial photography (right).
Contours are used as a visual tool to understand general topographic landscape characteristics. In addition, contours can be queried so that users can quickly identify areas above or below certain elevations. However, these contours have been interpolated, and are only approximate. Applications requiring precise elevation measurements will require the assistance of a professional surveyor.
The Virginia Geospatial Extension Program developed the contour layer using the TIN (described under DTM on page 6 of the supplemental METADATA file).
Data Type: Line
Attribution: Contour: values are expressed in feet
-State Plane Virginia North or South (Contingent on locality, refer to index map in the Appendix)
-Linear Unit: US Foot
Source: Virginia Geospatial Extension Program