How are Tracklog Timestamps and Time Zones stored and used in Basecamp?

When I look at the properties of a track that I have imported to Basecamp from my Garmin GPSMAP 62stc the Time column appears to have been adjusted back to GMT (I live in the UK) from the time where the track was recorded (in this case in Oman at GMT -4).
I don't have control of the time while it is being tracked because GPS always uses the local time.
I do have control of the time stamps on my photographs because the camera allows it.
Usually I remember to change the camera time to match local time and I take a photo just after I start tracking so I can synchronize the track and photo times and, if necessary, use the beautiful Geotag Photos /Photo Import/ Timeshift field in Basecamp.
However:
I had divided up my two weeks of tracklogs into a total of 87 Basecamp tracks so I could colour code each track to show the activity of that portion (e.g walking, driving, boating and using 4WD). Then, To geotag all my photos I had to select each track in turn, and set the timeshift to -4 every time!
If only it were possible to have a the timestamps left at local times and/or an option to tell Basecamp a Timeshift value to apply until I change it to something else, I could have got on a lot faster.

My question to Basecamp is: have I missed an option that would avoid my timezone timeshift problem?
If not, could someone please explain how the 62stc and Basecamp store the timezone of a track.

It is quite hard work looking at a detailed track log with GMT timestamps and doing the arithmetic to match the notes I make as I go along the actual trip. It is worse around midnight when GMT is the day before the actual recording.

I upgraded to the 62stc originally because it has a built-in 5mp camera which automatically geotags those pictures (ideal for photos of potholes which you want to report to the council for repairs!). Unfortunately my 62stc camera does not work any more after I dropped the unit. Everything else works - I expect the camera was not quite as rugged as the rest of the unit. Hence I can only use an independent camera.

Of course Basecamp's geotag feature saves me from taking a waypoint for every group of photos - which is great.

Any information and advice and any relevant new tweaks to Basecamp would be much appreciated.
Peter

0 Former Member over 10 years ago

Files always store time as Zulu. Note the Z in the timestamp.

Basecamp displays time based on the computer's time zone settings. It still knows the real (Zulu) time from the file. Your camera should be doing the same.

0 stuartmw over 10 years ago

To expand on what Red90rover said devices record timestamps in the UTC ("Zulu") timezone [which is what GPS satellites use] in track logs. BaseCamp (and other software) typically display times in your local timezone as configured on your computer. In your case UTC is your local timezone. If you change your computers timezone you should see the times shift.

0 pjwilliamsna over 10 years ago

Red90rover - thanks for the fact about Zulu time. That helps me to understand what is going on. However, I am not sure my Panasonic camera is using Zulu because I am allowed to set destination timezones and later, when geotagging with Basecamp I have to give the -4 hours timeshift timezone difference to Basecamp to get it to pick the correct photos taken on that particular tracklog segment.
I suspect that Panasonic is putting the actual time (as set by me in the camera) where it was taken in the photo's EXIF time field.

This difference of approach to time means it would be nice to have a Basecamp option to temporarily override the computer timezone or to set a temporary timeshift value. What do you think?
For me changing my computer timezone could lead to many other Windows PC confusions and problems.

Thanks for your input (and to Stuartmw)

0 stuartmw over 10 years ago

I suspect that Panasonic is putting the actual time (as set by me in the camera) where it was taken in the photo's EXIF time field.

That's what my camera does too. The camera probably only knows the time you set in it. It probably doesn't know (or care) what timezone you're in. GPS receivers do because as I said the GPS satellites transmit time in UTC.

[My camera actually does allow you to set two times ("Home" and "Away") and the zones they're in. I've never actually experimented to see what it actually saves in EXIF fields.]

0 Former Member over 10 years ago

Why not set the camera to GMT and leave it there? Wouldn't the photos and the tracks match up then?

0 pjwilliamsna over 10 years ago

Why not set the camera to GMT and leave it there? Wouldn't the photos and the tracks match up then?

Yes, now that I understand how GPS stores time as utc I could not bother to set the camera time to 'away' time.
That would make Basecamp geotag work more easily but it would leave the wrong time in the EXIF, I suspect, and time of day dependent subjects such as sunrises and sunsets could be confusing as well as working out where anything was taken when I didn't have a GPS track to go with it.

Come to think of it I wouldn't be surprised if the GPSMAP 62stc did not actually store the then current time zone somewhere in it's tracklog filing system - does anyone know?

BTW: Years ago my job included writing software to analyse (IBM) computer network traces which had (GTF) time stamps - so that may explain why knowing exactly how something actually works is important to me...

0 stuartmw over 10 years ago

...I wouldn't be surprised if the GPSMAP 62stc did not actually store the then current time zone somewhere in it's tracklog filing system ...

To my knowledge no Garmin device does that. It'd be a nice feature though (timezones can change over time).

0 pjwilliamsna over 10 years ago

I think you may be right - looking at the files on my Garmin I can't see where it would be stored.
I have just tried setting my PC time zone to Oman and Basecamp did then show the same track log with the expected times in Oman as you suggested.
BTW: I see UTC stands for Coordinated Universal Time according to Windows.

I am back to asking Basecamp to allow the timeshift value to be set until changed.

0 stuartmw over 10 years ago

Coordinated Universal Time

Coordinated Universal Time (French: temps universel coordonné, UTC) is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time (GMT). For most purposes, UTC is used interchangeably with GMT, but GMT is no longer precisely defined by the scientific community; also, some assert GMT can refer to British Summer Time (BST), which is one hour ahead of UTC.

Ideally track logs would contain UTC and local timestanps. UTC makes perfect sense for the reason I've already stated twice. Local would also be nice though.

0 Former Member over 10 years ago

Time zone management has been a significant issue for me over the years as well, since I live in Arizona (which does not observe daylight saving time) and do quite a bit of business in the UK and continental Europe (which of course are an hour apart). Then, to top it off, North America has seen fit to transition to and from DST several weeks offset from the rest of the world. I keep my tracks for decades, as I imagine many on these discussions do, and it's important to me to be able to work out the local time when the track was created.

It took me awhile to figure out that my Nuvis store the local time but that as soon as I transfer the file to my laptop, it's back to GMT, as outlined in previous posts. So I've taken a brute-force approach that involves embedding the number of hours to add or subtract from GMT to yield local time for that file on that day into the filename: 14 10 09 (+7). Crude, but effective. I rarely have more than a few files for any calendar day.

At least I don't have to deal with Newfoundland or India where they chuck an extra half-hour into the mix.