Adaptive compass calibration based on local field conditions

1. A method for calibrating a magnetometer, the method comprising:

responsive to a determination that a magnetic inclination is less than a threshold:

measuring first magnetic field data by detecting a magnetic field with the magnetometer through a first rotation path;

measuring second magnetic field data by detecting the magnetic field with the magnetometer through a second rotation path; and

determining calibration values for the magnetometer based on the measured first magnetic field data and the measured second magnetic field data.

2. The method of claim 1 , further comprising:

responsive to a determination that the magnetic inclination is greater than the threshold:

measuring third magnetic field data by detecting the magnetic field with the magnetometer through a third rotation path;

measuring fourth magnetic field data by detecting the magnetic field with the magnetometer through a fourth rotation path; and

determining calibration values for the magnetometer based on the measured third magnetic field data and the measured fourth magnetic field data.

3. The method of claim 1 , further comprising:

determining a position with a global navigation satellite system receiver; and

determining the magnetic inclination based on the determined position.

4. The method of claim 1 , wherein determining whether the magnetic inclination is less than the threshold comprises:

determining whether an absolute value of the magnetic inclination is less than the threshold.

5. The method of claim 1 , wherein measuring the first magnetic field data by detecting the magnetic field with the magnetometer through the first rotation path comprises:

associating data from the first magnetic field data with orientation data detected by an inertial measurement device.

6. The method of claim 1 , further comprising:

outputting, responsive to the determination that the magnetic inclination is less than the threshold, an indication to rotate the magnetometer through the first rotation path.

7. The method of claim 6 , wherein outputting the indication to rotate the magnetometer through the first rotation path comprises:

transmitting, to an output device through a wireless network, a command to display the indication on a screen of the output device.

8. A non-transitory computer-readable storage medium comprising computer program instructions to calibrate a magnetometer, wherein the computer program instructions, when executed by at least one computer processor, cause the computer processor to:

responsive to a determination that a magnetic inclination is less than a threshold:

measure first magnetic field data by detecting a magnetic field with the magnetometer through a first rotation path;

measure second magnetic field data by detecting the magnetic field with the magnetometer through a second rotation path; and

determine calibration values for the magnetometer based on the measured first magnetic field data and the measured second magnetic field data.

9. The non-transitory computer-readable storage medium of claim 8 , further comprising computer program instructions that when executed cause the computer processor to:

responsive to a determination that the magnetic inclination is greater than the threshold:

measure third magnetic field data by detecting the magnetic field with the magnetometer through a third rotation path;

measure fourth magnetic field data by detecting the magnetic field with the magnetometer through a fourth rotation path; and

determine calibration values for the magnetometer based on the measured third magnetic field data and the measured fourth magnetic field data.

10. The non-transitory computer-readable storage medium of claim 8 , further comprising computer program instructions that when executed cause the computer processor to:

determine a position with a global navigation satellite system receiver; and

determine the magnetic inclination based on the determined position.

11. The non-transitory computer-readable storage medium of claim 8 , wherein the instructions to determine whether the magnetic inclination is less than the threshold further comprise instructions to:

determine whether an absolute value of the magnetic inclination is less than the threshold.

12. The non-transitory computer-readable storage medium of claim 8 , wherein the instructions to measure the first magnetic field data by detecting the magnetic field with the magnetometer through the first rotation path further comprise instructions to:

associate data from the first magnetic field data with orientation data detected by an inertial measurement device.

13. The non-transitory computer-readable storage medium of claim 8 , further comprising computer program instructions that when executed cause the computer processor to:

output, responsive to the determination that the magnetic inclination is less than the threshold, an indication to rotate the magnetometer through the first rotation path.

14. The non-transitory computer-readable storage medium of claim 13 , wherein the instructions to output the indication to rotate the magnetometer through the first rotation path further comprise instructions to:

transmit, to an output device through a wireless network, a command to display the indication on a screen of the output device.

15. A device, comprising:

a magnetometer;

a processor, the processor configured to execute instructions to:

responsive to a determination that a magnetic inclination is less than a threshold:

measure first magnetic field data by detecting a magnetic field with the magnetometer through a first rotation path;

measure second magnetic field data by detecting the magnetic field with the magnetometer through a second rotation path; and

determine calibration values for the magnetometer based on the measured first magnetic field data and the measured second magnetic field data.

16. The device of claim 15 , wherein the instructions further comprise instructions to:

responsive to a determination that the magnetic inclination is greater than the threshold:

measure third magnetic field data by detecting the magnetic field with the magnetometer through a third rotation path;

measure fourth magnetic field data by detecting the magnetic field with the magnetometer through a fourth rotation path; and

determine calibration values for the magnetometer based on the measured third magnetic field data and the measured fourth magnetic field data.

17. The device of claim 15 , further comprising:

a global navigation satellite system receiver to determine a position of the device, wherein the magnetic inclination is determined based on the determined position.

18. The device of claim 15 , wherein the instructions to determine whether the magnetic inclination is less than the threshold further comprise instructions to:

determine whether an absolute value of the magnetic inclination is less than the threshold.

19. The device of claim 15 , further comprising:

an inertial measurement device, wherein the instructions to measure the first magnetic field data by detecting the magnetic field with the magnetometer through the first rotation path further comprise instructions to:

associate data from the first magnetic field data with orientation data detected by the inertial measurement device.

20. The device of claim 15 , wherein the instructions further comprise instructions to:

transmit, responsive to the determination that the magnetic inclination is less than the threshold, through a wireless network, to an output device with a screen, a command to display on the screen an indication to rotate the magnetometer through the first rotation path.