Point Scale Equations
• Take care in reading the literature. “While position calculations require high precision, point scale does not.”
- Leads to use of spherical ERM.
- Erroneous conclusion that point scale is independent of longitude. This is certainly not true for ellipsoids.
• For UT, a constant scale factor of 0.9996 (cscale) is used along the central meridian to reduce distortion.
• Error ? due to point scale distortion of meters per kilometer is where k is the point scale and is the un-distorted true distance. The linear error in a kilometer is then 1000 *? . For 10 kilometers the error becomes 10000 * ? .
Adjudication of distortion errors is application dependent