Accuracy Of Map Files - GPS TrackMaker Reference Manual

6.2 Accuracy of MAP Files

A small price is paid when using MAP files. Unlike GTM files that allow full edition and register the coordinates with
13 decimal places, the MAP files may present small errors of accuracy that depends how the file was created.
For Waypoints, the maximum error is 10 inches (25 cm) close to the Line of Ecuador.
For Tracklogs, the error depends on the maximum size of the largest segment. See the table below:
Maximum Size of the Largest Segment
8,958 yards
17,917 yards
26,875 yards
35,834 yards
...
2,284,513 yards
Above 2,284,513 yards
The maximum error may occur in equatorial region. As closer as Earth's poles, smaller will be the error.
To minimize the error in Tracklogs, avoid to create big segments together with small segments. Big segments
increase the error in the small segments.
The polygon 1 in the picture below must be avoided. To get a best result, transform it to the polygon 2 that is
more homogeneous.
Another way to eliminate big segments united to small segments is to use the toll called
located in Tools -> Tracklogs and Routes.
Tracklogs
Finally, remember that all information above applies only to MAP files and not to GTM files.
Maximum Error
10 inches
20 inches
30 inches
40 inches
...
69.72 yards
1328 yards
62
Homogenize Points of