Elevation Spikes making Virtual Rides Difficult.

[GotoesUser]

One of the cool features of a virtual riding platform such as Rouvy is that anyone can create a virtual ride from the video footage and GPS track of an activity. The problem though is that the final quality of the virtual route depends pretty much on the quality and accuracy of the GPS data used. We all know that if you record the same ride with multiple devices, such as a Garmin Edge, Wahoo Elemnt, Strava iPhone app, etc.) you can get quite different GPS data, especially when it comes to the elevation value. This elevation value is used to compute the grade, so having bad elevation values leads to spikes in the grade level, which makes riding the virtual route on a smart trainer not just inaccurate, but unpleasant as well. Imagine going up a climb with a steady grade of 5-6% and all of a sudden there is a "wall" of 15% or more! To fix this problem, the person creating the virtual route should manually correct the GPS data, looking for GPS data points where the elevation value went wacko, and correcting the values. This process can be very time consuming, especially when dealing with a GPS file from a long route. So here's the request: it would be nice to have a tool that could do this correction (smoothing out) of the GPS data automatically, using as "reference" an identical GPS track generated by a route creation tool such as Strava or RideWithGps. Let me know if anything requires clarification. Thanks!

[fulmar2]

OK, I added it. In order for this feature to work, you need to select “Interpolate Points”… then you can check the smooth elevation box, and adjust the slider as shown below:

Fix GPS Track for Rouvy, Peloton, or Zwift

Here is a screenshot of the outputted grade when using various levels of smoothing. Speed is the color (the speed you went, I assume). The height of the peaks represents the grade (but pay attention to the scale on the right).

Smoothing Elevation of GPS | TCS | FIT Files for a Trainer | Virtual Ride

Top image: your file
middle image: Slider set to middle setting.
bottom image: Slider all the way to the right (may be too smooth!)

Maybe give it a try, but you’re still going to have to pedal harder on your way near the top of the summit! I’m guessing that the change won’t be as abrupt now.

[GotoesUser]

Here is the elevation after using your tool.

The blue line is the file I used as a sample.
The red line is where I modified the blue file, adding in a big elevation spike; effectively "poisoning" it.
The yellow line is where I took the "poisoned" file and ran it through your tool with the slider at 25%.
the green line is where I took the "poisoned" file and ran it through your tool with the slider at 50%.

Elevation Profile for Rouvy Trainer Ride Fixed.

[fulmar2]

Glad it is working and thanks for the suggestion.