Methods to convert local sampling coordinates into geographic information system/global positioning systems (GIS/GPS)-compatible coordinate systems

Laying out a sampling transect in the field is a common task when researching natural systems and resources. With widespread availability of global navigation satellite systems (GNSS), such as the US global positioning system (GPS), it is becoming more common to resurvey legacy transects to establish them in globally referenced coordinate systems such as geodetic latitude/longitude or planimetric systems such as the Universal Transverse Mercator (UTM) or the State Plane Coordinate System (SPCS). Transforming local coordinates into a globally referenced coordinate system allows (1) disparate legacy surveys to be combined into a common geographic information system (GIS) database, (2) new GPS measurements to be incorporated into that same database, and (3) GPS-based navigation to be used for plot establishment and resampling. This article presents the mathematics necessary to determine the globally referenced planimetric coordinates of established linear, rectangular, or nominally rectangular transects (such as a rhombus) using formulas that are easily implemented on a spreadsheet. In addition, methods are given to determine the planimetric coordinates of new transects. Copyright © 2007 by the Society ot American Foresters