Incorrect Elevation Data from API near 22.24769, 113.91904 (Hong Kong Lantau Trail)

openrouteservice
1

We encountered an issue when retrieving elevation data via the OpenRouteService API. For a segment of the Lantau Trail (Hong Kong), the API returns extremely large elevation values (tens of thousands of meters), which causes incorrect elevation gain calculations in routing results.

Location:
Approximate coordinates: 22.24769, 113.91904

Steps to Reproduce:

  1. Send a request to the OpenRouteService API for route or elevation data covering the area around the coordinates above.

  2. Inspect the returned elevation values for points along that segment.

Expected Result:
Elevation values should be within realistic terrain range for that area (roughly 0–1000 m above sea level).

Actual Result:
Some returned elevation points contain values in the tens of thousands of meters, which is clearly invalid and breaks elevation-based calculations (e.g., ascent/descent totals).

Impact:
This issue leads to incorrect routing statistics and unreliable elevation profiles for users navigating this trail.

Request:
Could you please verify the elevation dataset or tile covering this coordinate region and let us know if this is a known issue or if a correction is planned?

Thank you.

2

Hey,

this is not an issue of the elevation dataset of this region, but of the underlying OSM data.

Elevation in OSM is given using the ele-tag that, according to its OSM wiki entry should note the height above sea level of a point, in metres.

If the ele-tag is present on an element, we take this to be accurate - after all, that is the point of OSM.

If we cannot find an ele-tag on an element, we get this elements elevation information from SRTM data.

In this case, there is node Node: ‪Tsam Chai Au‬ (‪420467292‬) | OpenStreetMap in the area - tagged with ele=810;803 - which is not a meaningful value, as it is not an elevation in metres.

What is probably meant here is that one source lists height as 810 metres, another as 803 metres.

Best regards

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