Calibration & benchmarks

A benchmark marks a fixed spot in the field with a known, averaged elevation. It does two jobs in this mode: it anchors a survey you drive so it can be calibrated later, and it lets you re-line a survey to its original elevation frame after the RTK base station has moved between sessions.

Dropping a benchmark

When surveying a field, tap the Benchmark button in the sidebar, then Drop New Benchmark:

1. Name it (e.g. "Gate corner"). Pick something you can physically find again.
2. Hold the machine still while the app averages GPS for 5 seconds.
3. The benchmark drops as a flag on the map and is saved with the survey.

The app requires at least one benchmark before it will start recording a survey, so you will usually drop one at the very start.

Calibrating to a benchmark

Returning to a field on a later day, the RTK base may sit slightly differently, shifting every elevation. To correct it:

1. Drive back to a benchmark you dropped before. You need to be within about 10 m (30 ft) of it.
2. Open the Benchmark menu and tap the benchmark in the list to calibrate to it.
3. Hold still for the 5-second average.
4. The app compares the new reading to the benchmark's stored elevation and applies the difference as an offset to everything you record from then on — so the new day's points line up with the original survey.

The benchmark badge

While surveying, the sidebar benchmark button shows the count of benchmarks, or the active offset once you have calibrated (e.g. "BM +3cm"). The offset also appears in the top stats bar.