Geotagging with ExifTool missing the related Altitude Tags

[R3DP]

I just discovered the command line
exiftool -geotag track.nmea a.jpg


Seem miss to produce "GPS Altitude" Tag and the "GPS Altitude Ref"

All other tags was there. Except the  "GPS Altitude"


A sample below show the GPS tags the exiftool -geotag track.nmea a.jpg produce, and you will notice it did not have the related Altitude tag.
Can you investigate the problem? or What I need to do to get the Altitude information tagged

Thank
---- GPS ----
GPS Version ID                  : 2.2.0.0
GPS Latitude Ref                : North
GPS Latitude                    : 45 deg 21' 20.90"
GPS Longitude Ref               : West
GPS Longitude                   : 75 deg 38' 54.72"
GPS Time Stamp                  : 16:51:28
GPS Date Stamp                  : 2010:02:18

[Phil Harvey]

It could be that the NMEA doesn't contain altitude information.

If you could attach a sample NMEA file I could investigate.

- Phil