5 ms·
> Anyhow, if your image shows recognizable landmarks with shadows, then it will be feasible to recover the exact point of view and the time of acquisition. Wit
by Ntrails 6y ago
> Anyhow, if your image shows recognizable landmarks with shadows, then it will be feasible to recover the exact point of view and the time of acquisition.
With what level of accuracy? Are you claiming you can confidently assert 2020-12-21 15:12 over, say, 2020-12-22 15:15 via shadows
- enriquto 6y ago> confidently assert 2020-12-21 15:12 over, say, 2020-12-22 15:15 via shadows Not at all. By visual inspection you can see whether it's the morning or the afternoon (if you know the orientation of the landmarks). I guess by image processing you could get a precision of +- 1h maybe?
- w_t_payne 6y agoHow precise is a sundial? How high is the resolution of the camera? I'd imagine that on a bright sunny day with a high resolution camera showing clean sharp shadows, it'd be possible to get a precision much better than +/-1h.
- enriquto 6y agoSure, I was thinking about a photo of human subjects in the foreground, with some distant buildings in the background. But if you photograph the shadow of the Eiffel tower on a clear sunny day you may be down to the precision of a couple of minutes.
- Ntrails 6y agoBut that's only if you can resolve the "which day" issue?
- enriquto 6y agoOh, yes, that seems a hard problem. But with sufficient effort (cloud patterns, parked cars, other people in the image) there is still a lot of information to extract. Especially if other people were taking exim-tagged photos in the same time and place and putting them on instagram.
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- CuriouslyC 6y agoThe arc of the sun through the sky, along with observable weather and variability in air quality could let you pin the date down with surprising accuracy. Two neighboring dates with similar weather would obviously be very hard, but even variation in cloud patterns could be enough to make an id.
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