A Low-cost Tracking Solution For VR Headsets

Abstract

Inaccurate and slow positional tracking are fundamental problems of low-cost VR solutions. These factors can induce motion sickness and therefore significantly deteriorate the user experience. There are already a variety of solutions available to track the position of a VR HMD, some of which can be made robust and
low-latency by inexpensive means.

This thesis proposes a low-cost, outside-in, optical tracking solution. As optical sensor a stationary camera with an IR pass filter is used to capture an array of IR LEDs, which are integrated at strategic locations within the frame of the HMD. By using the OpenCV library the 3D pose of the LEDs can be estimated, and used to change the perspective of the user within the virtual world.

In particular, this tracking solution incorporates a fast, cost-effective, modified camera, capable of capturing over 180 frames per second. With this camera and a custom designed polyhedral structure to incorporate the LEDs, the LED array can be calibrated quickly and tracked accurately even when oriented at an obtuse
angle with the camera. The high frame rate also allows for a redundancy in pose estimations, obtained by a mix of algebraic and iterative PnP solvers to further improve numerical stability and accuracy.

The tracking algorithm accurately tracks the developed prototype at short distances, even when placed in a noisy environment. The calibration procedure can also be performed fast, so that tracking can be resumed within a second when tracking has been lost due to occlusion. Recommendations for further improvements would be to integrate an IMU to provide tracking information in case that the HMD becomes occluded, and to overall improve tracking of rotational movement. Also, a higher resolution optical sensor should be
used to improve the range of this tracking solution.