How useful is the elevation field?

Hi all,

i’m wondering why the programmers of OSM made an elevation field (ele). Im my opinion this doesn’t make sense, because

  1. If somebody is correcting a way, he usually drags the nodes around, but the value of the elevation-tag is still the same. So he will create wrong information. Or in other words: the information about elevation gets lost! So its useless.
  2. If there’s a long straight road, then its only necessary to put 1 node at the start and 1 at the end. But in the OSM there are many roads where a straight road has a lot of nodes, because the creator tagged the elevation.

I think it would be much better if the elevation-info would be saved in the GPS-traces (blue-lines in potlach). And if 3D-information is needed, then a 3D- Editor would be the best, where you can align the drawn way at the blue lines. Same like in 2D, but now in 3D.

Of course it would be a lot of work to get a 3D Editor, but the original elevation-information is saved in the traces, and the more traces we have the more accurate would be the way.

best regards, Simon

Moving of nodes is able to cause other problems as well, so mappers should be aware of the effects of moving a node that has tags.

GPS collected elevation is not very sensible as the vertical accuracy is 10 meter at best. If you would collect a huge amount of tracks on a way one might be able to determine the most likely elevation based on statistics but otherwise satellite radar base elevation data (SRTM) would be more appropriate. It might be useful to provide elevation data for some areas where changes in elevation are sudden and radar data is not accurately positioned horizontally.

Having a 3D editor just for the scarce areas that cannot be mapped correctly using the radar data seems overkill to me.

Yes, but what should i do when i see a node which is obviously placed some meters besides the real road? Should I

  1. move the node to the right position and don’t change the elevation tag?
  2. move it and delete the elevation tag?
  3. leave it, and create a second node/way, which runs parallel to the first one?

I don’t want to arrogate a 3D Editor. I think it is no necessary at the moment. The thing is that we don’t mix raw-GPS-data, and data that we create on the map. In 2D we collect raw-GPS data from a street e.g. (the more tracks, the better), and in the editor we drag a NEW line, whose coordinates are some kind of mean values of the tracks). We dont write the collected 2D coordinates in it.
And like this we should do it with the 3rd coordinate (elevation). So the elevation tag is wrong in my opinion.

Greetings, Simon

ele tags are usually optional, and should probably be used only for known fixed heights, eg a survey point or a mountain peak.

I agree there is no way to properly translate the elevation to street data.

One interesting thing to try in the future, is collecting all the raw GPS data with elevation to generate a relief grid by interpolation. Then the 2D street maps can be mapped on this 3D grid to provide 3D street maps when necessary.


I think the solution everyone has beenlooking at is using external datasources like SRTM for DEMs/height.