Time Zone issue

  • While using OruxMaps on with Trackserver in live mode I noticed that time for accepted tracks is shown in offset to proper time.

    I am in +2 time zone. Android devices is set accordingly. OruxMaps Force UTM zone is set to 0, meaning leave it as is. WordPress is set to UTC+2 and hosting server is set to TZ Europe/Belgrade (which is UTC+2).

    Track is saved in GPX file which shows track point with time 15:12 (UTC).

    <time>2018-10-19T15:12:13Z</time>

    That is ok.

    But, Trackserver displays track point time as 10:11 instead of 17:11 as it should be.

Viewing 3 replies - 1 through 3 (of 3 total)

  • Not a solution but maybe some hints:

    The GPX 1.1 xml schema says time in the GPX file must be UTC.

    trackserver expects times to be local time, so Oruxmaps would have to send local times. I do not know if it does though. Maybe you have to force UTM zone 2. What would that do to the GPX files exported by Oruxmaps?

    IMHO it would be better if trackserver saved all times in UTC and converted them when displaying things. Right now uploading and downloading with different local time zones could lead to wrong times, at least that is what I believe (did not test).

    Plugin Author tinuzz

    (@tinuzz)

    Hi,

    First of all: UTM zones have nothing to do with timestamps, so that settings shouldn’t have any influence.

    It has been a long time since I messed with the time conversion code in Trackserver, but IIRC it’s like this:

    – Trackserver tries to store everything in local time. In retrospect, it might have been better to store UTC timestamps, but it’s too late for that now.
    – GPX files are supposed to have UTC time, and OruxMaps / MapMyTracks live updates also have UTC time, as far as I know.
    – Trackserver tries to convert all timestamps to local time. It uses WordPress’ timezone settings for that. If your tracks are made in a different timezone, that will surely lead to incorrect times displayed in Trackserver.

    That said, I can’t really explain why Trackserver would display your track with timestamps two hours earlier than UTC, instead of UTC+2.

    Timestamps are converted to Unix timestamps (seconds since 1-1-1970) and a timezone offset is added to them before storing them in the database. The offset is calculated as can be seen here:

    https://github.com/tinuzz/wp-plugin-trackserver/blob/master/trackserver.php#L3276

    Somehow, in your case the result is (presumeably) -7200, where it should be 7200. Surely, there must be a bug in there somewhere, but for me, it has always worked as expected.

    Can you verify the following things:
    – the value of the ‘timezone_string’ option in WordPress
    – the value of the php.ini setting ‘date.timezone’

    Regards,
    Martijn.

    One more problem with storing times as local time without timezone: When summer time ends, the points between 2am and 3am are a mess.

    Why is it too late to change that? Can’t an update convert times?

    Regards, Wolfgang

Viewing 3 replies - 1 through 3 (of 3 total)
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