[talk-ph] video mapping

Mark Cupitt markcupitt at gmail.com
Fri Sep 27 03:05:02 UTC 2013


when i was flying aerials using a video, we used to sync on the ground by
letting the gps stabilize then marking an event that saved the exact time
and we also flashed a strobe at the camera so that "start" point could be
determined. the camera time and time in the file could be  compared at
those two events and a difference established.

given the relatively slow speeds of a vehicle, you could probably get quite
close by covering the lens of the camera, then saving a way piont, assuming
the timestamp is saved as well, then just remove the lens cover at the same
and get going.

of course, you have to adjust for the time differences manually or post
process the gox file. we had some sppcialized software to do that, but i do
not have it any more, unfortunately. maybe there is something in one of the
newer apps that can do that.

setting the time on the camera and comparing the difference to the gps time
would also work, slightly lower tech option.

neither of these are "precision" options, but would give a little better
accuracy, if you had trouble syncing the camera time with the gps time.

of course if you want to get really high tech, stick a camera out each side
of the car, sync both cameras to the gps and just drive slowly. kind of
like google philippines style.

i do recall doimg some research on video cameras where they could actually
sync by an infrared signal or connector  but i never followed through
On Sep 27, 2013 10:23 AM, "Leonard Soriano" <banito_pinoy at yahoo.com> wrote:

> In synchronizing a GPS and digital camera before going out to the field,
>  I do this manually. I set the time of the camera as sync as possible with
> the GPS.
>
> Probably it might be the same process for video cameras. Video mapping
> might require a more perfect timing because since you are moving relatively
> fast, a difference in time between the two hardware could result to a
> mismatch of GPS coordinate and the captured video.
>
> --bunny
>
>
>   ------------------------------
>  *From:* Jim Morgan <jim at datalude.com>
> *To:* talk-ph at openstreetmap.org
> *Sent:* Thursday, 26 September 2013 10:49 AM
> *Subject:* Re: [talk-ph] video mapping
>
> maning sambale wrote, On Wednesday, 25 September, 2013 11:02 PM:
> > Nice article by Ervin on video mapping.
> > http://www.s1expeditions.com/2013/09/102-videomapping.html?m=1
> > I didnt know its possible to add gps coordinates as subtitles in a video.
>
> That is interesting. I'd probably seen that GPSbabel could export in SRT
> format, but it didn't occur to me that this was subtitles as it was out of
> context. Question: how do you get the timing of the video and GPX to
> sychronise? For a start you'd have to make sure the video recording device
> and the gpx recording device had their time set the same. Do you sync them
> up just by switching them on at the same time, or is there a way to embed
> the time in the video? GPX has time information included of course.
>
> Jim
>
> --
>
>     datalude: information security
>     e: jim at datalude.com
>     Philippines: +63 2 403 1311 / mob: +63 917 849 3939
>     Hong Kong: +852 5125 3392
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>
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