Author Topic: Measuring Route Distances  (Read 861 times)

ninthace

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Re: Measuring Route Distances
« Reply #15 on: 20:59:01, 21/08/20 »
I have not found a reliable source for ascent/descent on steep ground.  GPS is not that reliable for height and any slight error in horizontal position (plotted or measured) will result in a significant vertical error.  This is very evident when walking by large drops on routes such at the SWCP.  A slight error in in measuring horizontal displacement will either put you on the beach or at the top of the cliff.
Solvitur Ambulando

Eyelet

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Re: Measuring Route Distances
« Reply #16 on: 20:14:35, 06/09/20 »
I too use Viewranger, but the ascent and descent figures are definitely NOT to be trusted on steep ground, as the altitude mapping used is approximated - the Viewranger Landscape contour lines are suspiciously smooth and regular.


When you are planning routes, these apps are getting their elevation data from a Digital Elevation Model (DEM). A DEM is a grid with an altitude measurement for each cell.  The various free DEMs offer a grid that may be 30m, 60m or even 90m, which have a knock-on effect on the accuracy of cumulative ascent. The GPS Visualizer site has some helpful information on the several free DEMs that they have access to. OS have a very accurate DEM with a 5m grid which is not free, but I'm not sure if they use this in their app or one with a coarser grid.
« Last Edit: 20:27:23, 06/09/20 by Eyelet »

Rivingtonboots

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Re: Measuring Route Distances
« Reply #17 on: 07:21:51, 07/09/20 »
I've just bought a Realalt pedometer to replace the one I lost near Pendle Hill last weekend.
This one doesn't need to be clipped on a belt and can just sit in my pocket.
Mind you, I've lost quite a few