Treatment of Point Scale
Adjudication of distortion errors is application dependent.
Take care in reading the literature: “While position calculations require high precision, point scale does not.”
- Leads to use of spherical ERMs
- Erroneous conclusion that point scale is independent of longitude (this is certainly not true for OBSs).
For TM, a constant point scale of 0,999 6 is used along the central meridian to reduce distortion.
Error ? due to point scale distortion of meters per kilometer is ?= 0,999 6*k- DTRUE, where k is the point scale and DTRUE is the un-distorted true distance
- The linear error in a kilometer is then 1 000 *?.
- For 10 kilometers, the error becomes 10 000 *?.