Position Averaging
Position averaging improves the accuracy of a point measurement by collecting multiple GNSS readings at the same location and computing their mean. This is particularly useful when working without RTK corrections, as it can reduce the random error in standalone GPS positions from several metres to sub-metre levels.
Enabling Averaging
- Open Settings > Survey Settings.
- Toggle Position averaging on.
- Set the Number of samples - the number of readings to collect before computing the average (default: 2, configurable to higher values).
When averaging is enabled, every time you add a new point feature or a new vertex to a line/polygon, the app collects the configured number of samples before placing the point.
How Averaging Works
Collection Process
- You tap to add a point or vertex.
- Instead of placing the point immediately, the Averaging Progress bottom sheet appears.
- The app collects one position sample per second from the GNSS receiver.
- A circular progress indicator shows how many samples have been collected out of the target.
- Once the target is reached, the averaged position is placed on the map.
Averaging Algorithm
The averaging uses a running mean approach. For each new sample, every coordinate and quality value is updated:
- Latitude - averaged
- Longitude - averaged
- Height - averaged
- Accuracy - averaged
- HDOP - averaged
- VDOP - averaged
- PDOP - averaged
- HRMS - averaged
- VRMS - averaged
This produces a progressively refined position as more samples are collected.
Averaging Purposes
Averaging is triggered in two contexts:
| Context | When |
|---|---|
| Add new point feature | Creating a new point in a point layer |
| Add new vertex | Adding a vertex to a line or polygon feature |
Progress Display
The Averaging Progress sheet shows:
| Element | Description |
|---|---|
| Circular progress | Visual indicator showing samples collected vs. target (150 dp diameter) |
| Sample count | "X / Y" - samples collected out of target |
| Elapsed time | Duration of the averaging session ("Xs" or "Xm Ys") |
| Live accuracy | Current averaged accuracy, colour-coded by quality |
| Cancel button | Stops averaging and discards the collected samples |
Accuracy Colour Coding
The live accuracy display uses colour to give an at-a-glance quality indication:
| Colour | Accuracy | Quality |
|---|---|---|
| Purple | < 0.1 m | RTK-level precision |
| Blue | < 1.0 m | Sub-metre - excellent for most surveying |
| Green | < 5.0 m | Good for general mapping |
| Orange | >= 5.0 m | Poor - consider waiting for better conditions |
Practical Tips
More samples = better accuracy. For boundary surveys or control points, use 10-30 samples. For general asset mapping, 3-5 samples is usually sufficient.
Stay still while averaging. Any movement of the antenna during averaging introduces error. Use a survey pole or tripod for best results.
Averaging works with both the internal GPS and external GNSS receivers. When used with an RTK receiver in fixed mode, averaging can push accuracy into the sub-centimetre range.