Qt 5.8 | Qt Sensors | C++ Classes | QMagnetometerReading

Qt 5.8.0 Reference Documentation

# QMagnetometerReading Class

The QMagnetometerReading class represents one reading from the magnetometer. More...

Header: | #include <QMagnetometerReading>
qmake: | QT += sensors
Since: | Qt 5.1
Inherits: | QSensorReading

- List of all members, including inherited members

## Properties

- calibrationLevel : const qreal
- x : const qreal
- y : const qreal
- z : const qreal

- 1 property inherited from QSensorReading

## Public Functions

qreal | calibrationLevel() const
void | setCalibrationLevel(qreal calibrationLevel)
void | setX(qreal x)
void | setY(qreal y)
void | setZ(qreal z)
qreal | x() const
qreal | y() const
qreal | z() const

- 4 public functions inherited from QSensorReading

## Detailed Description

The QMagnetometerReading class represents one reading from the magnetometer.

#### QMagnetometerReading Units

The magnetometer returns magnetic flux density values along 3 axes. The scale of the values is teslas. The axes are arranged as follows.

The magnetometer can report on either raw magnetic flux values or geomagnetic flux values. By default it returns raw magnetic flux values. The QMagnetometer::returnGeoValues property must be set to return geomagnetic flux values.

The primary difference between raw and geomagnetic values is that extra processing is done to eliminate local magnetic interference from the geomagnetic values so they represent only the effect of the Earth's magnetic field. This process is not perfect and the accuracy of each reading may change.

The image below shows the difference between geomagnetic (on the left) and raw (on the right) readings for a phone that is being subjected to magnetic interference.

The accuracy of each reading is measured as a number from 0 to 1. A value of 1 is the highest level that the device can support and 0 is the worst.

#### Calibration

If the device is reporting low accuracy, then calibration might be needed before acceptable measurements can be provided. Basic calibration can usually be done by either rotating your device in a figure of eight, or by rotating the device along each of its three axes. For more information, check your device's documentation on how to calibrate the magnetic sensor.

## Property Documentation

### calibrationLevel : const qreal

This property holds the accuracy of the reading.

Measured as a value from 0 to 1 with higher values being better.

Note that this only changes when measuring geomagnetic flux density. Raw magnetic flux readings will always have a value of 1.

Access functions:

qreal | calibrationLevel() const

See also QMagnetometerReading Units and Calibration.

### x : const qreal

This property holds the raw magnetic flux density on the X axis.

Measured as teslas.

Access functions:

qreal | x() const

See also QMagnetometerReading Units.

### y : const qreal

This property holds the raw magnetic flux density on the Y axis.

Measured as teslas.

Access functions:

qreal | y() const

See also QMagnetometerReading Units.

### z : const qreal

This property holds the raw magnetic flux density on the Z axis.

Measured as teslas.

Access functions:

qreal | z() const

See also QMagnetometerReading Units.

## Member Function Documentation

### void QMagnetometerReading::setCalibrationLevel(qreal calibrationLevel)

Sets the accuracy of the reading to calibrationLevel.

See also calibrationLevel().

### void QMagnetometerReading::setX(qreal x)

Sets the raw magnetic flux density on the X axis to x.

See also x().

### void QMagnetometerReading::setY(qreal y)

Sets the raw magnetic flux density on the Y axis to y.

See also y().

### void QMagnetometerReading::setZ(qreal z)

Sets the raw magnetic flux density on the Z axis to z.

See also z().