Geodesy and Map Projections Flashcards
6 cards from real FUNDAMENTAL SURVEYING practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Geodesy and Map Projections flashcards as text
What is the scale factor in State Plane Coordinates?
Answer: The ratio of grid distance to ground distance
The scale factor (k) is the ratio of grid distance to geodetic distance on the ellipsoid at a given location.
What is the combined scale factor used for in surveying computations?
Answer: To convert ground distances to grid distances (or vice versa)
The combined scale factor (= ellipsoid factor × scale factor) converts ground distances to grid distances for use in SPC or UTM computations.
UTM (Universal Transverse Mercator) divides the world into how many zones?
Answer: 60 zones
UTM divides the world into 60 zones, each 6° of longitude wide, numbered 1–60 from west to east.
What is the central meridian scale factor in the UTM projection?
Answer: 0.9996
UTM uses a scale factor of 0.9996 at the central meridian to reduce maximum distortion across the 6° zone.
What is the 'convergence angle' (γ) in a map projection?
Answer: The angle between grid north and true (geodetic) north
The convergence angle (grid declination) is the angular difference between grid north and true (geodetic) north at any given point.
What does the 't-T' correction account for in geodetic surveying?
Answer: The difference between the geodetic azimuth of a line and its grid azimuth due to meridian convergence
The 't-T' correction (arc-to-chord correction) accounts for the fact that a geodesic on the ellipsoid projects as a curve on a plane grid.