Google Cardboard VR Sensors
Google Cardboard is a low-cost virtual reality platform that allows users to experience immersive content using their smartphones. The platform relies on various sensors to track head movements and provide a realistic VR experience.
Types of Sensors
Google Cardboard utilizes a combination of sensors, including:
Accelerometer
- Measures linear acceleration along three axes (X, Y, Z).
- Used to track head tilt and movements.
Gyroscope
- Measures angular velocity along three axes (X, Y, Z).
- Used to track head rotation and orientation.
Magnetometer
- Measures the Earth’s magnetic field.
- Used to determine the absolute orientation of the device.
Proximity Sensor
- Detects the presence of an object near the device.
- Used to pause or resume content when the user removes or inserts the phone into the headset.
Sensor Data Fusion
The sensors’ data is combined and processed using a technique called “sensor fusion” to provide a more accurate and reliable tracking of head movements. This involves:
- Filtering and smoothing sensor data to reduce noise and drift.
- Calibrating sensors to compensate for individual device variations.
- Combining data from different sensors to improve accuracy and stability.
Comparison of Sensor Capabilities
| Sensor | Measured Quantity | Accuracy | Limitations |
|---|---|---|---|
| Accelerometer | Linear acceleration | Good for tilt and translational movement | Affected by gravity, sensitive to vibrations |
| Gyroscope | Angular velocity | Excellent for rotational movement | Drift over time, can be affected by magnetic fields |
| Magnetometer | Magnetic field | Good for absolute orientation | Affected by magnetic interference, can be unreliable indoors |
| Proximity Sensor | Distance | Reliable for detecting presence | Limited range |
Example Code
The following code snippet demonstrates how to access and use accelerometer data in a Cardboard VR application using JavaScript:
if (window.DeviceMotionEvent) {
window.addEventListener('devicemotion', function(event) {
var accelerationX = event.accelerationIncludingGravity.x;
var accelerationY = event.accelerationIncludingGravity.y;
var accelerationZ = event.accelerationIncludingGravity.z;
// Process acceleration data to update VR scene
});
} else {
console.log("DeviceMotionEvent is not supported");
}
This code registers an event listener for the ‘devicemotion’ event, which fires whenever the device’s acceleration changes. The event object provides access to the acceleration values along the X, Y, and Z axes.