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Behind Holus: Digital Sensor Fusion and How It Works

Behind Holus: Digital Sensor Fusion and How It Works

Digital sensors like accelerometers, gyroscopes and magnetometers have a wide range of applications including navigation systems, autonomous robots, military applications, gesture recognition and virtual reality. This post will give you an introduction on sensor fusion, which is used for Holus application development.

Nowadays, most modern smartphones and tablets come with an accelerometer, gyroscope and magnetometer, which means it is rather easy for Holus to get sensor data from the connected device. Accelerometer measures the acceleration vector with respect to weight in units of gravity force. It has the gravity acceleration pointing toward the centre of the earth with the value of about 10m/s^2. This feature can be used to calculate tilt angle. Gyroscope measures rotation (angular velocity) around the X, Y, Z axes. The true orientation reading may change after subsequent motions in 360 degrees. The magnetometer measures the strength of the magnetic field surrounding the device. In the absence of any strong local fields, these measurements will be of the ambient magnetic field of the Earth, allowing the device to determine its “heading”, the top of the device, with respect to the geomagnetic North Pole and act as a digital compass. It measures the heading in degrees from 0 to 359.00, where 0 is north.

In conclusion, accelerometer has a gravity component. Gyroscope has accumulating drift error problem, but it is not sensitive to gravity, magnetometer provides a more precise measure of the device orientation with respect to the north, but it is not sensitive to motion acceleration. Each of sensors has its own strengths and weaknesses, so that sensor fusion is needed to use of multiple sensors so they compensate each other’s weaknesses. 

We are working on the algorithms to deal with different sensors and make them work together properly. By combining these sensors together, we have all of the tools necessary to create features like sensor calibration, position tracking, dynamic perspective correction and dynamic stitching. When Holus meets sensor technologies, I believe this combination will deliver people an immersive holographic experience.

- Will Chen, Creative Developer 

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