Texas Surveyors Practice Exam

What are the different types of north directions used in surveying?

1. True, relative, fixed, and variable

2. Geodetic, astronomic, grid, and magnetic

3. Absolute, relative, magnetic, and true

4. Standard, adjusted, absolute, and calculated

The correct answer is: Geodetic, astronomic, grid, and magnetic

The classification of north directions in surveying includes geodetic north, astronomic north, grid north, and magnetic north, making this the correct answer. Geodetic north refers to the north direction as defined by the Earth's curvature and is based on the reference ellipsoid used for geographical measurements. This direction is critical for GPS and other geospatial technologies, providing a consistent framework for referencing locations on Earth. Astronomic north is determined by the actual position of the North Pole as defined by the Earth's rotation. This direction is obtained using celestial observations, specifically the position of stars, and is essential for precise astronomical navigation and surveying. Grid north is tied to the coordinate system used in mapping and planimetric representations. It corresponds to the grid system laid down by surveyors for specific mapping purposes and is particularly useful in local plans where distortion from the Earth's curvature can be negligible. Magnetic north, on the other hand, is based on the Earth's magnetic field and varies depending on the observer's location. Compasses point towards magnetic north, which is why understanding its differences from true north is vital in surveying to avoid navigational errors. Together, these types of north provide comprehensive frameworks that surveyors use to measure and represent geospatial information accurately.