New ascent calculation algorithm is less accurate than before

[sky-runner]

@dimitrios-kanellopoulos, you were asking about testing of the new ascent / descent calculation algorithm introduced in Q1 update. I definitely notice some oddities and in some cases it produces way more ascent than before.

For example I did an easy run in my neighborhood, and it produced 563 ft (172m) of elevation gain, but after doing elevation correction in Strava that reduced to 426 ft (130m). That is a significant difference. Strava tends to be a bit conservative with ascent but not to such large degree, especially when running in a neighborhood on a relatively mild terrain. At one point I was watching my watch as I was waiting at a traffic light to cross the street. There was a slight gradual uphill before the stop, but after crossing the street there was a gentle downhill. However, surprisingly, once I resumed running, the altitude kept going up for another 40 seconds and gained another 18 feet as I was actually running downhill. That’s over 5 meters! There was no wind.

Here is the snapshot of that particular part of the run showing me stopping and resuming running. You can see that the altitude goes down while I am waiting, then bumps up even though, as I mentioned above, there was not such change in altitude and there was actually a gentle downhill.

In the past I also observed similar strange small but sharp changes in altitude, and I think they happened after stopping and resuming running too. I never pause my watch when stopping if that makes any difference.

Furthermore, @dimitrios-kanellopoulos, you mentioned that with the new algorithm there is a 2 meter threshold, them the ascent should increment at 1 meter at a time. However that isn’t what I observe! The ascent often changes in 1-2 feet increments, which is 30-60 cm. I can see that because my watch is configured in imperial units. I wonder if that contributes to excessive ascent calculation.

[Dimitrios Kanellopoulos]

@sky-runner its more accurate not less but I ll report this (maybe you wanna be specific on the title ie flat runs etc)

[sky-runner]

@Dimitrios-Kanellopoulos, No, it is less accurate or rather less stable. Some days it is ok but other days I notice way too much accent when running on gentle rolling hills of my neighborhood. As I showed in the above example, there was 20-25% extra ascent compared to Strava - after elevation correction in Strava. Strava tends to be very accurate on easy terrain. I suspect the extra elevation comes from FusedAlti because I see these weird bumps in elevation that aren’t actually there, and they are more noticeable after stopping running for a minute and resuming, for example when I wait at a stop light or have to clean after my dog.

I’ll look for other examples and update this thread.