I've just tried ExifTool geotagging by using NMEA log file and it works -no, I'm not surprised
. Now, before I start to implement that in GUI and to avoid time consuming experiments, few questions (just to clarify in my head):
1. Because logging happens in time intervals, Exif DateTime values will always differ those from GPS log file. I assume, that (because of this) ExifTool is interpolating Latitude, Longitude and Altitude values from nearby (closest time match) values. That is, in most cases, these three values (and GPSTimeStamp) written inside Exif can't be actually found inside log file. Am I correct?
2. My logger allows logging Latitude/Longitude values only (thus, no Altitude). I haven't tried that option yet, but... if that value is missing in log file, will ExifTool create GPSAltitude tag anyway? If yes, what value will be in there?
3. Assuming my camera has correct local time and logger always uses UTC... As long I'm taking photos in my "local (time) area", there's no need to use -GeoTime option, because ExifTool will automatically know TimeZone difference by using PC's system time(zone). Am I correct?
4. I'm in Moscow and I take photo there at 10:00AM (their local time). Camera is set to their local time as well, thus DateTimeOriginal=10:00:00. Because logger uses UTC, log file will contain time=07:00:00 (Moscow's TimeZone=+3h). When comming home (TimeZone=+1h) I'm geotagging my photo... what -GeoTime value must I use:
+1 -because that's my local TimeZone?
+2 -because that's the difference between Moscow and my (home) TimeZone?
+3 -because that's Moscow's TimeZone?
Is it possible you would limit GPSAltitude precission to (say) max two decimal numbers? I assume, commercial gps units aren't not even that precise. Speaking for me, one decimal point would be more than enough...
Thanks for taking time to answer.