Which statement correctly describes the typical magnitude of the coefficients p and q in grid conversions?

• A. They are usually on the order of 10^-4 or 10^-6
• B. They are typically around 1
• C. They are large values usually exceeding 10
• D. They are random numbers between 0 and 10

Answer: (A)

In grid conversions, p and q are tiny factors in the linear part of the transformation that describe how the x-coordinate changes with respect to x and y. They’re dimensionless and represent very small deformations from the identity (no change). Because grid corrections are usually small refinements rather than large shifts, these coefficients stay extremely small, typically on the order of 10^-4 to 10^-6. Larger values would imply a substantial distortion across the grid, which isn’t how these local adjustments are designed to behave. That’s why the best choice is the one that reflects these tiny, precise corrections.