A 3-minute read on what the tool does, which control option to pick, and how to read the report. The fastest way to learn it is to run the sample job and click around.
The sample job is made up (invented coordinates, simulated measurements). It's not anyone's real survey.
Every traverse has small errors: a few seconds in each angle, a few hundredths in each distance. When the traverse closes, those errors show up as a misclosure. Least squares spreads that misclosure back over the measurements in the most likely way, using how accurate each measurement should be. Long, careful sights get changed a little; short, shaky ones get changed more.
Just as useful, it checks the work. If one shot needed a much bigger correction than the instrument allows, it's probably a mistake (a wrong HI, the wrong prism, a bumped tripod), and the report points to it.
A traverse on its own has a shape, but it could sit anywhere and point any direction. Control pins it down. Pick the option that matches what you trust most.
One point keeps its given coordinates, and the bearing to a second point sets the rotation. Every other point with given coordinates becomes a check, so you see if anything moved.
Use it when you start from known control in the data collector, like re-running a site traverse or checking a prior one. Tip: pick the point you set up on first and your first backsight.
The traverse is adjusted on its own measurements, so it keeps the exact shape you measured. Then it's turned and slid (never stretched) to sit on the GPS points as closely as possible. The report shows how far each GPS point is from the traverse.
Use it when the traverse is tight and the GPS is the weaker data: downtown, under trees, short observation times. It's the “export a few GPS points and rotate to them” method, done with every GPS point at once.
Each GPS point pulls on the traverse according to how accurate it is, and the traverse bends slightly to fit them all. Bad GPS will bend good traverse, so only use this when the GPS is solid.
Use it when GPS was in the open with good fixes, or static sessions with known precisions. Give a weaker GPS point a bigger ± under advanced settings.
The tool reports the scale difference between the traverse and the GPS (in ppm) but never applies it. Scaling a traverse to GPS can hide real problems, so that call stays with the surveyor.
Start at the top. What this means sums it up in a few sentences and lists what to do next. Under that, each item is labelled:
| Label | Meaning | What to do |
|---|---|---|
| Fix | Something is almost certainly wrong in the field data. | Fix it (or leave the shot out) and run it again. Don't use the coordinates yet. |
| Check | Possibly a problem; could also be fine. | Look at the field notes for that point or setup before relying on it. |
| Note | Something the tool did or assumed for you. | Read it once so nothing surprises you. |
| Good | A check that passed. | Nothing. |