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How to convert between WGS84 and other calculated heights?

2

I have a couple of questions:

  1. Is there a tool that can convert local height into wgs84?

  2. Is there an OSM map render that will display the local height, or both heights together?

asked 29 Aug '12, 09:38

Dafo43's gravatar image

Dafo43
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converted to question 29 Aug '12, 09:58

SomeoneElse's gravatar image

SomeoneElse ♦
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This was previously added as an answer to this question, but is really a question in its own right.

(29 Aug '12, 09:59) SomeoneElse ♦

An example of an item with different elevations in different co-ordinate systems is Croagh Patrick in the west of Ireland.

(29 Aug '12, 10:05) SomeoneElse ♦

2 Answers:

2
  1. I think it will be hard, as there is so many local referentials, depending mainly on the sea level considered by the country.
  2. I will again suggest mine :-) You can click on each peak and see OSM tags

answered 29 Aug '12, 11:09

NicolasDumoulin's gravatar image

NicolasDumoulin
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edited 29 Aug '12, 12:06

2

As I already hinted on in my answer to the previous question the situation is a bit of a mess.

In the examples you used you naturally know because the value of ele and ele:wgs84 are the same that you actually have WGS84 height over the ellipsoid in front of you.

But if you have a naked "ele" tag you will only be able to use heuristics to determine which reference system was used in generating the value.

For Ireland this will probably work as a converter (not tested) http://www.osi.ie/calculators/converter_index.asp?alias=/services/gps-services/co-ordinate-converter

answered 29 Aug '12, 19:06

SimonPoole's gravatar image

SimonPoole ♦
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Thanks for the replies. I added a few elevations for mountains in Dublin in wgs84 format. I took a nearby mountain with both values to work out the difference over local and wgs84 height. Far from perfect but better than having no information I think.

(30 Aug '12, 14:41) Dafo43

If you do so, you may indicate source:ele:wgs84=extrapolation

(30 Aug '12, 15:11) NicolasDumoulin

Source code available on GitHub .