Data and maps · · 1 min
How far off a GPS is under the forest, and why we say so
Under closed canopy the satellite signal degrades. How we combine RTK GPS, drone and GIS, and how we state the precision of every point we deliver.
An RTK GPS can place a point within centimeters in the open. Under a closed canopy, things change: the crowns block and reflect the satellite signal, and precision drops. A map that doesn't say so treats unreliable points as good ones.
Why precision drops
- Fewer satellites in view: the crowns cover part of the sky.
- Reflected signal (multipath): the signal bounces off trunks and leaves before reaching the antenna.
- Loss of the RTK correction: without a fixed solution, the receiver falls back to much lower precision.
How we make up for it
- We measure from clearings when possible and carry the point over with distance and bearing.
- We occupy difficult points for longer and record the type of solution the receiver reported.
- We cross-check with drone imagery and GIS to review boundaries and clearings.
How we state it
Every point we deliver carries its estimated precision and the method used to take it. That way, the reviewer knows which points can support a legal boundary and which are only a reference.
A stated margin of error doesn't take value from the data: it tells the user how far they can trust it.
Written byRuben AlmendaresIT
Data and maps
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