Head-Mounted Device Tracking With Timed Light Difference Detection
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Solution Overview
Problem
Existing tracking techniques for input devices in extended-reality environments are cumbersome and error-prone due to interference from external background light-emitting elements and noise, leading to compromised user experience.
Innovation Solution
A system comprising a tracking device with a camera and a controller that obtains timing information to control the light source to illuminate different amounts of light at non-overlapping times, allowing the camera to capture images and calculate image intensity differences to identify pixels illuminated by the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing tracking techniques detect and geometrically match light from light-emitting elements against small clusters of infrared light, then tracking of input devices can be achieved, but the process becomes highly time-consuming and results in wastage of processing resources
Solution Approach 1:
The patent applies periodic action by implementing time-division multiplexing where the light source emits light in periodic time slots (first time slot, second time slot, etc.) rather than continuously. The camera captures images during specific time slots when the light source is active, enabling the system to distinguish tracked light sources from background light by their temporal emission patterns. This periodic illumination scheme reduces processing time and resource wastage while maintaining tracking accuracy.
2Adaptability or versatility
If existing tracking techniques use light-emitting elements arranged to be visible from all angles, then the input devices can be tracked from any orientation, but external background light-emitting elements and background noise create interference and confusion
Solution Approach 1:
The patent applies segmentation by dividing the tracking process into distinct time slots where different light sources are activated sequentially. Each light source has its own designated time slot for emission, and the camera captures images only during those specific time slots. This temporal segmentation eliminates interference from background light-emitting elements because they do not emit light during the assigned time slots of the tracked light sources, thereby maintaining full angular coverage without confusion.
Solution Approach 2:
The patent implements periodic action through time-division multiplexing where the light source follows a periodic emission pattern (active during first time slot, inactive during second time slot, active during third time slot, etc.). This periodic behavior allows the camera to distinguish between the tracked light source and background light by capturing images only during the periodic active phases, thereby eliminating background interference while maintaining omnidirectional tracking capability.
3Illumination intensity
If multiple light sources illuminate simultaneously in a real-world environment, then the scene appears naturally lit, but tracking becomes cumbersome and error-prone due to interference between light sources
Solution Approach 1:
The patent applies periodic action by implementing time-division multiplexing where multiple light sources illuminate the scene in a periodic, non-overlapping manner rather than simultaneously. Each light source is activated during its assigned periodic time slot and remains inactive during other time slots. This periodic illumination scheme maintains adequate scene lighting while eliminating interference between light sources, thereby ensuring reliable and accurate tracking without compromising illumination quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables simple, fast, accurate, and improved tracking of the light source, even in the presence of external background light, facilitating a more realistic and immersive user experience.
Implementation Method 1
control the camera to capture a first image and a second image during the first period of time (t0-t1) and the second period of time (t2-t3), respectively
Data Source
AI summary
A system includes a tracking device and a light source. The tracking device has a camera and a first controller. The camera captures a first image and a second image. The first image is captured during a first period of time (t0-t1) and the second image is captured during a second period of time (t2-t3). The first controller is coupled to the camera and configured to obtain first timing information and second timing information; form timing instructions; and communicate timing instructions to light source over a communication interface. The light source is configured to use timing instructions to illuminate first amount of light and a second amount of light. The first controller is further configured to calculate image intensity difference between the first and second image to identify from first image pixel(s) illuminated by the light source.