Mileage problems

Zoltan Hites's Avatar

Zoltan Hites

02 Aug, 2020 08:53 PM

I understand that there are some variations from some maps when it comes to mileage distance. Of course, GPS is going to have variations as well. But I do have to say that I have never had a software that is as off as Cal Topo. I think you guys have a great thing here but the distances can not be trusted and are dangerously off. I have been backpacking for over 20 years using everything from Map and compass, Forerunners, GPS devices, and Nat Geo Topo. Everything is pretty accurate to each other. But your software is the only one that is off my miles..... literally, not .5 or .3 but 2 miles. This is a very consistent issue, having to check this on three trips now, from Cal Topo. Not just some trails a lot of trips that I have planed then cross-referenced with maps and other software. I had to this because of a trip I had planned with Cal Tope turned bad when there was a 2.5-mile error in the measuring. That is huge.

This needs to be addressed ASAP. This is not a slight variance depending on what I am using. Every other device, software, apps are within .3 miles. So again that is an issue with Cal Topo. I hope this is addressed and not ignored like that last post. This is great software but can't be used in its current state.

  1. Support Staff 1 Posted by Julie on 03 Aug, 2020 05:02 PM

    Julie's Avatar

    Hi Zoltan,

    I'm not really sure what you are referring to here - planning a trip by drawing lines, or recording a track with the app.

    When drawing lines on a map, a lot of products are going to be using the same underlying data sources. No one is going out there and measuring every detail by hand. The closest anything comes to that is, which is where we get a lot of our data. This data is subject to both human error and GPS error, especially in steep and/or heavily wooded terrain. There is nothing in our code that would make the program over- or under- estimate line length.

    In regards to tracking with the app, a lot of other apps do some GPS data filtering while recording. We instead record exact tracks without filters subject to GPS variability, and it’ll be more variable in tree cover and steep slopes. We may consider filtering tracks in the future but at this time we do not do that with our track recording. That said, we actually have done extensive testing comparing to Garmin, Suunto, etc, and find the results to be quite reasonably comparable to each other.


  2. Julie closed this discussion on 03 Aug, 2020 05:02 PM.

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