Could someone clarify for me if the only way to automatically record positional accuracy values for iNaturalist observations is to take photos from within the app? On my own Android phone, accuracy values are automatically recorded if take my photo from within the app, but not if I use my phone’s camera app and upload it later. Some of the threads I’ve read here seem to suggest that iOS users have accuracy values automatically populated even when they take a photo outside of the app. Could someone please confirm if this is the case? Thanks!
iOS started recording horizontal accuracy for photos taken with the default camera app since like iOS 10 or 11 or so. I’m not sure if any Android phones do this. You might see if a third party camera app will record horizontal accuracy.
You probably already know that you can always manually edit the accuracy value if you don’t like the result from your camera.
Yes, what I’m really trying to understand is what I should expect the accuracy of observations without manually edited accuracy values to be. I’ve been filtering out observations that have high values for accuracy (really, high positional uncertainty) but of course there is still plenty of positional uncertainty left in observations that lack accuracy values.
For accuracy of recreational-grade GPS (found in cameras, phones, and hand-held consumer GPS units), the rules-of-thumb I was taught (and have confirmed in the field by taking repeated readings at survey monuments) is that accuracy is 5 - 10 m when there’s an open view of the whole sky, and about double that (10 - 20 m) with moderate forest cover. Much worse in canyons or near tall buildings where there’s no direct view of multiple satellites and possibly distorted or reflected signals. So, for most of my observations with GPS where accuracy is not auto-recorded, I set it at 10 m.
Sorry, I can’t remember where I got those numbers. Professional survey systems can get down to cm accuracy.
Yes, those are about the same numbers I have both heard and verified.
That can vary widely depending on how location services are configured on each phone. I always try to be in airplane mode (cell signal off), wifi off, and with a good GPS app running in the background to continually refresh the satellite fix. Not too battery intensive with cell and wifi off. With cell service on, positional uncertainty can get much larger depending on if/how the phone tries to integrate cell triangulation with GPS data.
I’ll add, that when I first started in iNat and got my first phone with GPS capability, it was typically 10-20m accuracy. My camera that I use now is typically 1-5m. I am mostly working with trees and have canopy overhead, and I have noticed that my phone doesn’t have a magnetometer but does have an accelerometer, so can’t tell what direction I am travelling but can tell that I AM moving and how fast. When under canopy, and using a GPS app to see where on the map I am (eg when trying to locate and walk to a GPS marker for a tree) it starts to increase the accuracy circle as I move, but if I turn around and go back, it continues to increase the size of the circle until I eventually get back to seeing the sky and it can “re-fix”. So it really depends on your device, and on the application and how it handles the signals it can see. My camera, for instance, does not record accuracy value in the image exif at all, whereas my phone does.
Personally I ignore the accuracy. It is where the GPS was recorded but the specimen photographed is often farther away from the camera lens than the accuracy, so to me its kind of worthless. It gives enough of a general location that honestly, if it is even 30 meters off, big deal.
If you really want accuracy, get a Garmin - the accuracy of phones is worse than even the old eTrex Legends that are dirt cheap used (but need a serial port). Phones don’t actually use satellite data, they triangulate from signal repeaters.
Well, that’s just plain wrong! Some phones do have GPS receivers and use both GPS and cell towers to calculate position. I can still locate when I am far outside cell coverage (very sparse on the East Coast of New Zealand), but unless I have the map downloaded in advance I just can’t see where that location is in relation to the map! My phone lists location services as: GPS, AGPS, LTEPP, SUPL,GLONASS… But it IS TRUE that when I am in town and indoors (like right now), I can still get location on my phone, but my camera (which only has GPS) can’t… but that is more about the phone having both capabilities!
Many of us take the time to move the pin to where the subject actually was, but without a way of knowing whether that has been done, I agree that accuracy is rather moot in the iNat context.
If you move the pin to where the specimen actually was then the geolocation accuracy of the device is meaningless because you moved the point the reported accuracy refers to.
But yes I concede there are phones with actual GPS satellite receivers.
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