I'm looking for a way to determine my position and orientation accurately within a building, ideally to within 6 inches. I know that using external devices may help, but I'm exploring a couple of approaches. One idea is to utilize the camera to create a sort of fingerprint of the surroundings and then match it with known locations. However, this process is quite challenging. Another approach could involve using built-in UWB and Bluetooth beacons. While this could provide precise location data, figuring out my orientation seems trickier, especially because phone compasses can be unreliable due to magnetic interference, like that caused by phone cases. I heard that the iPhone 15 has dual UWB antennas which could aid in orientation, but Apple doesn't allow developers access to that data. Any suggestions?
3 Answers
For accurate indoor positioning, you'd need some high-end gear similar to what surveyors use, like Differential GPS transmitters. These devices provide local high-accuracy references that work alongside satellites, but GPS signals weaken indoors. You might need several DGPS stations if you want reliable positioning. As for determining direction, phone compasses aren’t very accurate, and they might not offer reliable data unless you're moving. Plus, if you're just stationary, it doesn't help much to know which way you're facing.
Placing NFC chips at designated spots could be an option, but it might get cumbersome. Bluetooth beacons would be a better choice for triangulating your position within the space. They allow for fairly accurate 2D positioning, but you still wouldn't know which way you're facing unless you measure your position over time with multiple beacons. It’s not the neatest solution, but it should theoretically work.
You could potentially use the phone's accelerometers for inertial navigation if you hold it in a stable position relative to your body. However, while ARKit can track your movement, it operates on a relative basis. It sets a starting point and measures movement from there, but without a reliable compass reading (which can easily be affected by external magnets), it won't know true north or give you absolute orientation accurately.
That makes sense! So the reliance on magnets can really compromise the compass accuracy. It seems like combining multiple sensors might be necessary for better results.
Exactly! Using three beacons should help give a more directional sense as you track movement over time, even if it’s a bit messy.