Site Grid
Definition
A rectangular coordinate system established across a site, usually with the origin at a datum peg and axes aligned to magnetic north or true north. Context positions, finds, and survey data are all reported within the grid so that features can be mapped relative to one another.
- Shape
- Rectangular coordinate system
- Origin
- A datum peg
- Axis alignment
- Magnetic north or true north
- Use
- Maps context, finds and survey data relative to each other
Common questions
Why establish a local site grid instead of using GPS coordinates directly?+
A local grid with round, simple coordinates is easier to work with on the ground for measuring, plotting, and recording finds by hand, and it can still be tied back to a real-world GPS position through the datum peg for external reference.
What is the practical consequence of choosing magnetic north versus true north for the grid?+
Magnetic north drifts over years and location, so a grid aligned to it needs the declination recorded at the time of survey; true north stays fixed, making it the more durable reference if the site data will be compared or reused years later.
Related terms
- Backsighting
- The process of orienting a total station by pointing it at a known reference point (backsight) after setting it over the instrument...
- Datum Peg
- A fixed ground marker with precisely recorded coordinates that serves as the origin point for a site grid. All spatial measurements on...
- Resection
- A method of determining the instrument station's own coordinates by measuring angles and distances to two or more points of known position....
- RTK-GPS
- Real-Time Kinematic Global Positioning System: a satellite-positioning technique where a static base station transmits correction data to a roving receiver in real...
- Total Station
- An electronic instrument that simultaneously measures horizontal and vertical angles and distance to a reflective prism, computing three-dimensional coordinates directly. Typical angular...