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Confused By BaseCamp Geotagging

Former Member
Former Member
I live in Utah, Mountain Daylight Time. I went for a hike in Arizona, Mountain Standard Time. My Etrex 30 knew the difference and as soon as I crossed the border the Etrex clock lost an hour. My camera was set to Mountain Standard Time, so when in AZ the camera and the Etrex should have been in sync. However:

When I got back home to Mountain Daylight time I had to adjust the time offset for the Arizona photos 1 hour ahead (to Mountain Daylight Time) to get them to position correctly on the map.

What gives?
  • Former Member
    0 Former Member
    Did you check the track data? I would suspect the track time zone used for the track is constant (if it weren't the total time taken for the track would be all messed up, and you might have two track points at different locations but at the same time), and the parts in Arizona were recorded in Utah time.

    All BaseCamp does is compare the timestamp from the photo to the timestamps on the track.

    So as long as the device doesn't write out the time in UTC, or with time zone information attached, I don't think there is much BaseCamp can do.
  • Former Member
    0 Former Member
    The track was Mountain Daylight, so BaseCamp did the right thing. I guess I need to figure out why the Etrex showed a different time on the screen than it was registering in the tracklog.
  • Former Member
    0 Former Member
    As Falagar said, the track recording MUST use the timezone it started in for the entire track. Anything else would end up with a track that makes no sense.

    Example, you start a track 5 minutes before crossing a time zone boundary. If the track recording changes the time stamps to the new time zone, if you are travelling west you risk having the first 55 minutes of points in the new time zone with time stamps EARLIER than the first 5 minutes of tracks from the original time one.

    Conversely, if you are heading east you end up with a 1 hour hole in the track file.

    In either case the track file and related stats end up being rather silly.

    If you want the timestamps used for geotagging to reflect the "local" timezone you need to start a new track when you cross a time zone boundary. .... Well, you really just need to start the new track at the time you first pull out your camera in the new time zone.

    ...ken...
  • Former Member
    0 Former Member
    Actually, timezones are probably irrelevant. The entire track in question was recorded in Mountain Standard, but the moderator at GPSfiledepot suggested that I look at the timestamps using a text editor. The time stamps on the points are saved in UTC. So my Mountain Daylight is really UTC - 8. Log ends at 23:56 UTC and my hike ended at 15:56 Mountain Daylight. Both MS and BC show the log ending at 15:56, so the real question is where they get the time offset, my system clock?

    The fact that the Etrex could tell the difference between Mountain Standard and Mountain daylight is also irrelevant to the geotagging although it will make sure I don't miss breakfast when the alarm goes off.
  • 0
    so the real question is where they get the time offset, my system clock?


    From the time zone settings of Windows.
    Doesn't BaseCamp have an option to correct for the time zone, like most geotagging programs do? Or even better, an automatic correction based on location, just like your GPS...
  • Former Member
    0 Former Member
    As I said at the top, BC has an option to adjust the offset between the camera and the track. If I lived in Arizona, it would be up to Windows to figure out that the time was Mountain Standard. (And I see the system clock has an "Arizona" setting.)
  • 0
    I believe the time is based on the settings on the computer used with BaseCamp.

    I recently did a trip to Arizona and New Mexico from California.The GPSMAP 62s always showed the correct time zone for my location and the camera clock was properly maintained for the time zone. I had to perform a 1 or 2 hours offset in BaseCamp to get the geotags correct.

    Examining the GPX files, the "trkpts" use "Z" (aka UTC or GMT) time. The GPX filenames used the date and local time for the file name.

    The GPS was turned off each evening and back on the next morning.

    John