High point and low point symbols when following Oregon track

[Auntie Helen]

I've been using my Garmin Oregon 650 on my Germany tour and as I have been riding through hilly areas I have seen the symbols for low point and high point appearing on the track.

The thing is, I can't work out on what basis it adds them. The longest and steepest hill did not have one, sometimes slight undulations are included. They can't be switched off which can also be annoying when I have the 'distance to next' field showing as I want to know how far it is to a waypoint - instead it shows distance to the next high or low point.

Anyone know the lowdown on these things?

[JonBuoy]

This sounds like the same problem.

[Auntie Helen]

Ah, that is useful, thanks.

[Ham]

We have the same model, when I used it with tracks from ridewithgps mapping from openfietsmap (from http://garmin.openstreetmap.nl/) loaded as well as the basemap I found that high and low points were consistent and reasonably accurate (to about 100m)

There are only three places the data could come from: The base map, the loaded map and the track. I suspect that it might be a combination of all three? 

Actually, looking at the GPX there is no elevation data, so it is just the quality of the mapping.

Code: [Select]

<rtept lat="43.07481000000001" lon="-7.305790000000002">
      <name>Right</name>
      <cmt>Turn right</cmt>
    </rtept>
    <rtept lat="43.06754" lon="-7.326620000000048">
      <name>Left</name>
      <cmt>Turn left onto LU-P-1204</cmt>
    </rtept>
    <rtept lat="43.060610000000004" lon="-7.324790000000007">
      <name>Left</name>
      <cmt>Turn slight left onto LU-P-1611, LU-P-1611</cmt>
    </rtept>
    <rtept lat="42.94216" lon="-7.394810000000007">
      <name>Straight</name>
      <cmt>At roundabout, take exit 2 onto LU-P-1611, LU-P-1611</cmt>
    </rtept>

[Auntie Helen]

I've just looked at my GPX and elevation is always 0 so it must be getting it from somewhere else. I'm using OSM for my mapping.

[Oaky]

I got fed up of these occuring too often on my eTrex when navigating tracks which had elevation data in them #9e.g. tracks downloaded from ridewithgps or similar).

I like to have the "distance to next" and "waypoint at next" fields showing, in order to see how far I am from the waypoints I have defined, and these were being pretty much entirely hidden by fairly minor high and low points. 

Stripping the elevation data from the gpx track helps with this - the unit still finds some high and low points using elevation data in one of the OSM maps I have on it but these seem much fewer and further between than if you give it the elevation data in the track gpx.  (There is a message to that effect when I select a track from the "Where To" menu - "loading track with elevation data from the map" or something similar).

I've never really noted where the remaining high/low points occur or don't occur, so don't have any feeling for what garmin's algorithm might be.  They've usually seemed reasonable to me at the time.

[Ham]

I've just looked at my GPX and elevation is always 0 so it must be getting it from somewhere else. I'm using OSM for my mapping.

Looking at http://www.openfietsmap.nl/ the following

What is available on OpenFietsMap?
Topographic data with contour lines (5 m interval)
cycling routes, paths and cycling-nodes ('fietsknooppunten')
routable for cyclists and pedestrians (not suitable for car navigation)
address data  with housenumber search (complete for the Netherlands, elsewhere incomple

So, it may just be checking that button option to make it work. (it's the Routable Bicycle (Openfietsmap Lite) button, third down)

****WARNING*****WARNING*****WARNING******

Do not trust openfietsmap for routing unless you are happy with comedy off roading

[fuaran]

The full version of OpenFietsMap includes contours lines, but "OpenFietsMap Lite" doesn't.

I'm not sure if the contours actually work for elevation profiles and high/low points anyway. I don't think they are in the correct format. I suspect the Garmin is using the basemap, or some other sort of preloaded elevation data.