OS Maps online error

Discussion in 'Gadgets & Tech' started by OneBeardedWalker, Feb 7, 2019.

  1. OneBeardedWalker

    OneBeardedWalker Summit Camper

    Afternoon all,

    I do apologise if this has been mentioned on the forum beforehand, I did look but couldn't see anything.

    I've heard rumours of an error calculating ascents on OS maps online (premium version) but had never noticed it before today.

    Plotting a route across Dartmoor (when I should be working) I noticed that over a distance of 6.69 KM OS charted an ascent of 17 km. The estimated timing for the route was therefore given at 3h 16mins.

    The attached image shows a contour line by Top Tor reading 400 metres and the OS route marker showing 985.30 metres.

    I thought this might be of interest to those who use OS maps online and, like me, had not yet spotted the error and, perhaps like me, thought that they were just super fast walkers instead.

    OS MAPS.png
  2. stormin'

    stormin' Section Hiker

    I think the OS calculation is for total ascent of your route, not the actual height you are at. The obvious contour line cannot lie:angelic:
  3. OneBeardedWalker

    OneBeardedWalker Summit Camper

    Cheers @stormin' so you reckon that it is correct then? I'm not too sure 17km of total ascent in 6.69km traveled seems excessive for Dartmoor...

    My thinking is that the readings the online software is taking into account are different to those shown on the map (e.g. the OS thinks it is at 930 metres whereas the map shows it to be at 400) so it is calculating total ascent on the basis that the first hill has an ascent of 930 metres.

    Perhaps I'm totally failing to understand this...

    [EDIT] You're right @stormin' Total ascent is shown as 6.69km + the distance of the route =17km so while I was wrong this still seems excessive...doesn't it?
  4. edh

    edh Thru Hiker

    Load the .gpx file into another online site, gpsies, CalTopo and see what figures they give...
    OneBeardedWalker likes this.
  5. stormin'

    stormin' Section Hiker

    Distance travelled is given as km, height gained and lost is given as metres. Your waypoints will give you the distance in between each one.
  6. WilliamC

    WilliamC Thru Hiker

    6.69km in 17km is about a 40% slope, or about 2 in 5, which is about as steep as most walks get, so unless you're walking uphill steeply for the whole 17km on some currently unknown 6,690m British mountain, I think something is wrong.
    OneBeardedWalker likes this.
  7. OneBeardedWalker

    OneBeardedWalker Summit Camper

    I re-mapped (is that a word) the route and it came out as 8km (I added a slight detour at the end but essentially the same route) with a total ascent of a much more reasonable 233 metres...

    Looks like it was an error the first time around.
    edh likes this.
  8. HillBelly

    HillBelly Trail Blazer

    In this month's TGO there is a letter about this. There is a problem with inaccurate ascent calculations when using the snap to path feature. OS have now acknowledged this problem. It is not occurring when plotting routes freehand. So best switch off the snap feature to get the accurate figures.
    Dave V and OneBeardedWalker like this.

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