Mapping gps data to photos by using gpsbabel and gpsPhoto.pl

I bought a Garmin GPS device in the US, which was cheaper than in Japan. The prices are almost twice expensive even though the devices are customized to display Japanese letters. I think it's rip-off...

By the way, I could map GPS data to my pictures. Quality of pictures seems to not be changed. I think it's nice! Here's the way:

• To convert Garmin DB format to GPS eXchange format:
• $ gpsbabel -i gdb -f <input gdb file> -o gpx -F <output gpx file>
• To map GPS data to photos as geo-tags:
• $ gpsPhoto.pl --dir <photo directory> --gpsfile <gpx file> --timeoffset 28800 # 28800 = 60*60*8 (PST+8), 25200 (PDT+7)
or,
• $ gpsPhoto.pl --dir <photo directory> --gpsfile <gpx file> --tz-guess=zone.tab --timeoffset guess

What is complicated is about timezone. My camera records date as a local time. But gpsPhoto.pl handles data as UTC. So user must adjust date. I wonder that it's useful if camera can record data as UTC because I also have to be adjust the date when I go to other countries whose timezones are different.

If we use zone.tab which is expected to be located at /usr/share/zoneinfo, gpsPhoto.pl guesses the time difference and adjust the time offset. We will have to do something else once we passed over and changed timezones. So it is the best that our cameras can record dates in UTC, I think. However, can Exif handle date for this purpose?