setting the clock?

CesiumJS
1

If I set the clock using JulianDate the resulting view will be wrong by my local time offset (PST = UTC-0800).

e.g.,

viewer.clock.currentTime = new Cesium.JulianDate(jDay, jSec); // gives the wrong view

viewer.clock.currentTime = new Cesium.JulianDate(jDay, jSec - 8 * 3600); // gives the right view

By wrong I mean that the sun location/terrain lighting is wrong by the UTC offset…

Any help?

Thanks, Matt.

2

Where are you getting jDay and jSec from? JulianDate always uses the UTC time zone.

3

I’m starting with a unix timestamp and calculating jDay and jSec (php unixtojd()).

The conversion is correct:

unixSec = 1437497376 gives:

jDay = 2457225

jSec = 60576

But if I use these values the resulting view is off by +8 hours.

4

Looks like you’re not accounting for the fact that Julian days start at noon, not midnight.

your unix timestamp corresponds to: 2015-07-21T16:49:36+00:00

converting to JD with http://aa.usno.navy.mil/data/docs/JulianDate.php produces: 2457225.201111

separating into day number and seconds of day for the constructor produces: 2457225, 17376

feeding that into the JulianDate constructor returns: 2015-07-21T16:49:36Z

your value for jSec is off by 43200 which is 12 hours.

5

You’re right. That fixes it. Thank you very much. - Matt