Accelerometer

Kinect for Windows 1.6, 1.7, 1.8

The Kinect for Windows Sensor contains a 3-axis accelerometer configured for a 2g range, where g is the acceleration due to gravity.

This allows the sensor to report its current orientation with respect to gravity.

Accelerometer data can help detect when the sensor is in an unusual orientation. It can also be used along with the floor plane data calculated by the SDK to provide more accurate 3-D projections in augmented reality scenarios.

The accelerometer has a lower limit of 1 degree accuracy. In addition, the accuracy is slightly temperature sensitive, with up to 3 degrees of drift over the normal operating temperature range. This drift can be positive or negative, but a given sensor will always exhibit the same drift behavior. It is possible to compensate for this drift by comparing the accelerometer vertical (the y-axis in the accelerometer's coordinate system) and the detected floor plane depth data, if required.

Reading and Understanding Accelerometer Data

The Kinect for Windows SDK provides both native and managed methods for reading the accelerometer data. For native, use INuiSensor.NuiAccelerometerGetCurrentReading. For managed, use KinectSensor.AccelerometerGetCurrentReading. The Kinect SDK does NOT provide a change notification event for the accelerometer.

The accelerometer reading is returned as a 3-D vector pointing in the direction of gravity (the floor on a non-accelerating sensor). This 3-D vector is returned as a Vector4 (x, y, z, w) with the w value always set to 0.0. The coordinate system is centered on the sensor, and is a right-handed coordinate system with the positive z in the direction the sensor is pointing at. The vector is in gravity units (g), or 9.81m/s^2. The default sensor rotation (horizontal, level placement) is represented by the (x, y, z, w) vector whose value is (0, -1.0, 0, 0).

Figure 1.  The Kinect Accelerometer coordinate system

Accelerometer Data and Recording

When recording the Kinect data streams, the accelerometer reading is read and recorded per frame. On playback, the accelerometer reading from the most recent retrieved frame is returned.