Geodesy and Control Surveys Flashcards

The State Plane Coordinate System (SPCS) uses which map projections?

Answer: Lambert Conformal Conic and Transverse Mercator

SPCS uses Lambert Conformal Conic for states with greater east-west extent and Transverse Mercator for states with greater north-south extent.

In the Universal Transverse Mercator (UTM) system, each zone spans how many degrees of longitude?

Answer: 6°

The UTM system divides the world into 60 zones, each spanning 6° of longitude, for a total coverage of 360°.

The combined scale factor (CSF) in grid surveying accounts for:

Answer: The ratio of grid distance to ground distance at a given location

The CSF converts ground distances to grid distances (or vice versa) by combining the map projection scale factor and the elevation factor.

Meridian convergence (mapping angle γ) is defined as:

Answer: The angular difference between grid north and geodetic north

Meridian convergence is the angle between grid north and geodetic (true) north at a given point in a projected coordinate system.

Continuously Operating Reference Stations (CORS) primarily support:

Answer: High-accuracy GPS/GNSS positioning through continuous reference data

CORS stations provide continuous GPS/GNSS tracking data that surveyors access to perform high-accuracy positioning and control surveys.

The combined scale factor for converting ground distances to grid distances is computed as:

Answer: The elevation factor multiplied by the grid (projection) scale factor

CSF = (elevation factor) × (grid scale factor), where the elevation factor accounts for height above the ellipsoid and the grid scale factor comes from the map projection.

In the UTM system, what is the scale factor at the central meridian of each zone?

Answer: 0.999600

The UTM system uses a scale factor of 0.9996 at the central meridian to limit the maximum scale distortion within each zone to ±0.04%.