Following a route line vs following a map path

Overlay and base map

The acid route and the path beneath it can come from different evidence.

A saved route line is geometry from a plan, recording or shared file. It is drawn over the map so its order and shape remain visible. The base-map path is a mapped feature supplied by the map dataset and rendered according to the current style and zoom.

The route may have been recorded recently over a path that is missing from the map. The map may contain a well-attributed right of way while an old route drifts beside it. Both lines can also derive from the same earlier source, so visual agreement is not always independent confirmation.

Keep the layers conceptually separate. One describes the journey someone intended or observed. The other describes a feature that a mapping system knows about.

Several possible causes

A mismatch does not identify which source is wrong.

Position noise can shift a recorded line beside the path, particularly under trees, beside rock or between buildings. A planned route can contain sparse points or be snapped to a different map version. Simplification can cut bends.

The base map has its own uncertainties. A path may be surveyed imprecisely, changed on the ground, drawn at a generalised scale or omitted. Rendering can hide minor paths at one zoom and reveal them at another. Two paths at different levels may appear to cross.

• Route ageAn older file may predate a diversion, closure or newly mapped line.
• Recording qualityA wandering trace can be offset even when the person used the correct path.
• Map completenessAbsence from one map is not proof that a physical path is absent.
• Reference mismatchConversion or coordinate errors can shift an entire dataset systematically.

Useful, not conclusive

Consistent agreement supports interpretation but does not grant access.

When the route follows the mapped path through many distinctive bends and junctions, the agreement helps show how the two datasets relate. A small, broadly constant offset may suggest position or source alignment rather than a different intended path.

Neither line proves that the route is lawful for the activity, open today or suitable in current conditions. A visible path may be private, permissive, closed temporarily or mapped with incomplete access tags. A GPX can reproduce another person's movement without explaining their permission or circumstances.

Geometry can show where two lines agree. It cannot settle every question about why the line exists or whether you may use it.

When the lines part

Use route, map, position and ground as separate clues.

1. Measure

   Look at the scale of the mismatch.

   A few metres under poor sky view is a different problem from a route leaving along another valley.

2. Trace

   Compare the line before and after the disagreement.

   See whether the route returns to the mapped path, follows another feature or remains consistently offset.

3. Check

   Read current access and physical evidence.

   Use signs, closures, rights information, contours and the actual path. Do not force the route through ground that contradicts them.

4. Record

   Preserve the discrepancy for later review.

   Do not rewrite the source route in the field merely to make the lines overlap.