Store altitude in photos.

[holgerosm@…]

Please store the altitude in photos as it is done already for latitude, longitude, and date/time.

[bastiK]

I'm not sure how to interpret the EXIF specification: On the one hand the field is called "GPSAltitude", which suggest normal (ellipsoidal) WGS84 elevation. On the other hand they talk about sea level as reference, so this would be geoid height.

Btw., GPX has tags for both: <ele> and <geoidheight>.

[holgerosm@…]

My Android phone sets the fields "GPS Altitude Ref" and "GPS Altitude" with such values (extracted with exiftool):

GPS Altitude Ref                : Above Sea Level
GPS Altitude                    : 157 m Above Sea Level

So I think they mean geoid height. At least that is what I would expect if I read "sea level". I could do some tests to find out what my phone really does, but there is no guarantee that the phone does the right thing.

GPX's <geoidheight> is something else (difference between geoid mean sea level and WGS-84 ellipsoid height 0.0). I never found out what the reference for GPX's <ele> is. My logger software allows me to convert to mean see level or to WGS84 and stores the result in <ele>. So I would just take the GPX <ele> and store it to the EXIF "GPS Altitude".

[bastiK]

Fair enough. In ​[o28398].

[holgerosm@…]

Thanks for implementing this!

Note: It seems that the height of WGS-84 ellipsoid is meant to be stored in the EXIF GPS Altitude. I didn't find a real reference, but some clues. The Android standard camera app stores the WGS-84 elevation. The main reason is that the Android GPS API call delivers that elevation. An iPhone seems to do the same. The only value I found for the EXIF GPSMapDatum is "WGS-84". Someone recommended to set GPSMapDatum to WGS-84 to define what the reference is (​http://stackoverflow.com/a/1720727).