[PATCH] exif image timestamps are presumed to be in local time

[tsok]

Current JOSM seems to default to thinking exif image timestamps are in local time. The timestamps used to be presumed to be in UTC a couple of months back. I came to this conclusion after importing images with JOSM version 423 and noticing I have to offset the sync timezone 3 hours (which is the UTC timediff today here, tomorrow it will be 2 hours..) to get it right.

So I propose there should be a preference setting in JOSM, which allows the user to select between UTC and local timezone for image timestamps. I keep all my gear in UTC because it's just easier and more consistent that way, especially with the summer/winter time things.

Tapio

[Hasienda]

there is another, duplicate ticket #775 describing this behavior most likely with more up to date revision (revision number not mentioned there)

[xeen]

This seems to apply to AgPifoJ as well (found out while investigating #2124).

[xeen]

The source of this is tools/PrimaryDateParser. It sets <Calendar> to output in UTC which then sometimes converts even though it shouldn't. Setting it to output in local time fixes this problem but may cause others elsewhere.

While testing I found JOSM converts the GPS track (it adds one hour as I live in GMT+1) while doing nothing for photos. Changing the converting seems risky – while fixing the here mentioned issue it might break things for other people that take advantage of this "error".

Instead, I propose a different solution: AgPifoJ/JOSM could simply calculate the difference between the first photo and the first GPS point and find the most suitable timezone in an +-15 minute range. This will always fail if there hasn't been made a photo in the first 15 minutes of the GPS track, but providing two slider bars (one for time zone in 30 minute steps and one more fine-grained ("offset")) solves this. I doubt most people care about the time zone as long as it works and being able to adjust visually pretty much solves this.

Will work on my suggestion for AgPifoJ.

[xeen]

This adds the "auto guess" feature to AgPifoJ as suggested. I had to change the internal handling from milliseconds to seconds because of long overflow otherwise. On the other hand Auto Guess is able to match tracks and photos even if they're several days apart.

Also fixes AgPifoJ ignoring "Cancel" in file picker.

[stoecker]

Fix in [o13927].