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I used symbian and sports tracker to trace the jogging path. Then export to kml and used free tool to convert it to svg.

How ever, when I check this trace each time there is a elevation difference, the trace gets longer than real path on a map should be.

Is there any tools to remove or clamp the data to starting altitude or 0m meters ? Tried the sports tracker "clamp to ground" / "relative to ground" / "Absolute" but all of them gave exactly the same trace which was wrong.

asked 20 Nov '11, 13:02

testrai's gravatar image

accept rate: 0%

Perhaps you could upload an example KML somewhere and then someone could suggest how to remove the altitude from it (if that's what you need; I'm not convinced I understand your problem though).

A random KML file on my PC has something like:


in it, of which the ",0" at the end is the altitude. I'd have thought that it might be possible to change the altitude to 0 using a half-decent text editor?

(21 Nov '11, 14:39) SomeoneElse ♦

Your question is about "altitude", but from the context it is apparent that you mean "elevation". The word "altitude" means height above ground. "Elevation" means height above mean sea level.

(21 Nov '11, 19:30) user8192

You all have right topics - thank you

This hasn't yet got nothing to do with osm, because the trace gathered with sportstr seems to be wrong. Of course if you are jogging uphill and downhill, want the real run length, and not the flattened(altitude removed)+not so long trace.

Or am i stupid here - are maps drawn like that or on a flattened surface ?

I'm happy if i can flatten the file either kml or in gpx format. But how ?

(22 Nov '11, 20:20) testrai

ok, i made a picture to be more clear. is there a way to make the bottom result? (with nokia+sports tracker, or do i have to buy android)

(22 Nov '11, 20:40) testrai

Sports Tracker only uses OpenStreetMap map images as a backdrop to your trace. The altitude data you're seeing has been gathered from your GPS receiver, and has nothing to do with OpenStreetMap, which doesn't actually store any altitude data for any features.

There are some tips for improving GPS accuracy on our wiki, but other than that you should contact either the manufacturer of your GPS receiver (or phone if you're using its built-in GPS), or Sports Tracking Technologies, the publishers of your App.

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answered 20 Nov '11, 17:16

Jonathan%20Bennett's gravatar image

Jonathan Ben...
accept rate: 18%

edited 20 Nov '11, 17:17


I don't think you'll find a solution with the device itself. But there definitely are tools to modify a trace file after the fact, and zero-ing the altitude should be a easy and common operation.

I don't know which tools those would be though. gdal is one, but that may be too programing-oriented for the OP. Some programs, like googleearth, have a "ignore altitude" option, but I think they only do the modification in memory, and do not update the trace file.

(21 Nov '11, 09:27) Vincent de P... ♦

As SomeoneElse hinted, both KML and GPX files are just XML files. That means that you can open them with a simple text editor, see how they are structured, and make some edits. Check wikipedia for an xml primer if you need it.

Opening one of my gpx file, and the same one converted to kml (using ogr2ogr), you quickly spot the <ele> tag (for gpx) and the <SimpleData name="ele"> tag (for kml). Check your own files in case they are structured differently. Deleting those should achieve what you want.

There are many ways to delete those, it depends on what you're comfortable with. You can use your text editor to search+replace, if the search field accepts regexps. You can use 'sed' if you are using a unix-derived OS (including Linux or MacOSX) : "sed 's@<ele>[0-9.-]*</ele>@@g' myfile.gpx > newfile.gpx". There are some xml-specific editors out there too if they feel better for you.

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answered 22 Nov '11, 22:28

Vincent%20de%20Phily's gravatar image

Vincent de P... ♦
accept rate: 19%

Thank you

This must be that i'm stupid. Because i removed the last col from coords in the klm file - the altitude

and after that using the tool and still got the same trace widht what was too long.

So perhaps the sports tracker already makes some calculations into those coordinates and that's why they are wrong.

(23 Nov '11, 11:05) testrai

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question asked: 20 Nov '11, 13:02

question was seen: 8,193 times

last updated: 24 Nov '11, 12:50

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum