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How many cameras apart from the iPhone have a gyroscope for orientation?

Am I right to assume that there is a standard way to “tag” an image with the direction the camera was pointing in, as well as the GPS position?

Do any cameras have positional tracking better then a GPS?

I am thinking about a method to join photos when the subject does not have enough “random” detail for the current software.

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    I believe what the devices have are accelerometers and not gyros. By measuring the gravity vector along 3 axes, and with the addition of a compass, the device can resolve its orientation. Theoretically, you could do this with gyros, but calibration would be required each time you turn on the device. If there are gyros in the iPhone, my guess is that they only sense angular motion (e.g., for games) but not the orientation itself. Again, one can calculate this using accelerometers. – ysap May 16 '11 at 21:33
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    @ysap: you should add your comment as an answer. – Paul Hadfield May 16 '11 at 21:55
  • @PaulHadfield - technically, it does not answer the question, since I don't know for sure that no cameras have gyros. – ysap May 16 '11 at 23:15
  • @ysap They have accelerometers (measures orientation relative to gravity), gyros (measures angular velocity, which is usually zero during a photo), and a compass (measures orientation relative to magnetic north). The accelerometer + compass tells you the absolute direction the camera is pointing. – endolith Oct 6 at 13:30
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The gyroscope in an iPhone doesn't actually let you track the direction the camera was facing at the time of a shot. All it does it track motion--it has no frame of reference to determine what point of the compass the camera is actually facing.

The "digital compass" in the iPhone 3G S onwards can give some idea of that, except that it's designed to be used when the iPhone is more or less flat. It would thus require a mirror to be fitted to the camera lens to be useful, and in any case compass data isn't included in the EXIF info. I would expect that any camera providing directional capabilities would be using an equivalent "digital compass" using a magnetometer.

  • The digital compass doesn't need to be flat, it measures in 3D. Why would it need a mirror? – endolith Oct 6 at 13:33
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To have "positional tracking better than a GPS" you will need an INS (Inertial Navigation System) of the kind that exists in cruise missiles... The on-board sensors you get in your camera/smartphone merely tell you the orientation and motion, but not the position.

  • Itai's comment implies that the Casio does use a sort of dead-reckoning to use sensors to estimate position. – Hank May 16 '11 at 23:36
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    @HenryJackson - What it means is probably that the camera have a GPS for tracking its position, but uses the accelerometers for local tracking, originating at the last reliable GPS recorded location. Continuous position estimates based on a $2 sensor set is guaranteed to drift in amounts that will render it useless for geotagging. – ysap May 16 '11 at 23:42
  • INS doesn't have any different sensors than the ones in your phone. They probably have less noise, but they're fundamentally the same thing. You integrate acceleration to get velocity, and then integrate that to get position. That's what "inertial" means. Combine with GPS using a Kalman filter so the two types of sensors keep each other up to date. – endolith Oct 6 at 13:36
  • @endolith - you contradict yourself. It is like saying Shelby Cobra doesn't have any different components from a Model T. Both have four wheels, and internal combustion engine, a steering wheel and a windshield. It's just that the Cobra has more power... – ysap Oct 6 at 17:19
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Among the current cameras with GPS you will notice that more than half also record orientation. Just look at the row towards the bottom of the table that says GPS at the above link.

Now, I have no idea if they use accelerometer or gyroscopes but all those record the orientation of the camera. At least the Casio H20G, which is also among the digital cameras to include a built-in GPS with orientation, is known to use accelerometers because it actually tracks your position indoors (or other places where GPS do not reach) too by measuring direction and speed from the last known GPS location. They call this Hybrid GPS.

  • How heck the the camera can know your direction and speed without GPS?! Man, the future is so awesome! – Andres May 17 '11 at 1:31
  • Sorry I was not clear enough I guess. It measures from the last known GPS location, so it has to get a GPS lock at some point and keeps calculating from there until the next GPS lock. The H20G is among the list of cameras with GPS. – Itai May 17 '11 at 1:44
  • But it really can detect your movements or it just traces a straight line from the last gps lock to the new one? (BTW, may be I sounded ironic, but i was really amazed about the tracking thingy) – Andres May 17 '11 at 2:10
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    Yes, it tracks movements using 3-way sensors for direction and rotation. It has to since it geotags BEFORE reaching the next GPS lock: casio.com/products/Cameras/Hybrid-GPS/EX-H20G – Itai May 17 '11 at 2:51
  • How do they record orientation if it's not in the EXIF tags? – endolith Oct 6 at 13:34

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