Computation of elevation gain / loss overestimated in route planning

Benjamin shared this question 3 months ago
Answered

Hi,


I have lately noticed that elevation gain and loss computed on Locus route planning are overestimated compared to googlemaps or Komoot computation.


On the GPX attached a 362km in the alps, Google is computing around 6500m of gain , Komoot 7300m and Locus 9036m !

Note that I have applied "Update elevation function" (because I created the route with the web app, it was computing around12000m of elevation..)

To me the difference is significant and impact your decision when your plan such a trip.


Even on small RECORDED trip, e.g. 60km not so hilly, Locus indicates around 600m of vertical gain (again based on the recorded trip with 'update elevation' applied) against 560m as predicted by Komoot and recorded roughly by my garmin computer.


Do you have an explanation?


Does it depend on the Map and associated DEM data?


Best regards,


Benjamin


PS: congrats for the good work by the way I love the app alot.

Replies (3)

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Hello,

I am sorry for the late reply, this ticket was lost somewhere.

The reason could be difference among raw data of each provider and also calculations and data smoothening could be different.

Even when you record your track with GPS, it probably won't be the correct number, because there are too many deviations.

Anyway we have plans to update this whole functionality and its calculations, so it should be better soon.


Zdenek, Locus team

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Which elevation data is used for the (offline) route planner calculations?

I hope the elevation files in the locus folder. IF so, @Benjamin could download and use the more accurate DTM elevation files by Sonny. If you use BRouter, then you're already using them, see BRouter website.

Nevertheless, all elevation calculation are only as accurate as the data. And if the all the small ups and down aren't in the data, then the calculations will be off. Depending on the smoothness of the actual terrain , the smoothing of the elevation data and the route calculations, the total sum elevation is either too high or too low. I guess, I'd prefer if it rather overestimates the sum total elevation ‒ cause there are always ups and downs (esp. on my trails) and the resolution of the elevation data simply isn't high enough to detect those.

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2

Hello,

BRouter uses its own elevation data and for other routers you have to download elevation data for the map you are using (from the Locus store).

But any of these data aren't precise. If you use raw data of any ascend you can imagine it like stairs. The altitude is defined for some mesh points. Between those points app needs to calculate the approx. altitude. And because there are some deviations, data are usually smoothened.

In addition, the quality of data for different locations varies significantly - some areas has newest lidar data available, some has sparse grid of points (especially mountains).

In general the altitude calculations are quite challenging. But as I wrote, we have big task ahead of us to improve it.


Zdenek, Locus team

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I'm excited to hear more from this elevation related update! Elevation information is so important, yet most map services just think in 2d.

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