Active Brightness Pixel Invalidation for Time-of-Flight Depth Sensing
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Solution Overview
Problem
Time-of-flight depth cameras suffer from artifacts such as motion blur and multipath interference, leading to inaccurate depth values due to rapid movement and multiple infrared radiation paths with different travel times, respectively.
Innovation Solution
A computer-implemented technique that generates frequency-specific sensor readings, calculates active brightness measurements, and invalidates pixels if the variation in these measurements exceeds a prescribed threshold, effectively removing corrupted data caused by motion blur and multipath interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the depth camera performs exposure of its sensor to capture depth information, then depth values can be obtained for processing tasks, but motion blur artifacts occur when the depth camera or objects move quickly during exposure
Solution Approach 1:
The patent applies preliminary action by performing pixel invalidation based on active brightness variation before depth values are processed or used for tasks. The system pre-identifies and marks corrupted pixels using AB variation thresholds, so that subsequent depth processing operations can simply skip these invalid pixels rather than dealing with corrupted data later in the pipeline.
2Measurement precision
If the sensor detects infrared radiation reflected from the scene to provide sensor readings, then depth information is obtained, but multipath interference occurs when the sensor receives radiation from several different paths with different travel times
Solution Approach 1:
The patent converts the harmful effect of multipath interference into a useful detection mechanism. By measuring active brightness variation across multiple frequencies, the system identifies pixels affected by multipath interference and invalidates them. The harmful multipath signals that would normally corrupt depth measurements are instead used as indicators to flag and exclude affected pixels from processing.
3Reliability
If frequency-specific sensor readings are generated and active brightness measurements are calculated to identify corrupted pixels, then depth image quality is improved by removing artifacts, but additional processing steps and computational complexity are introduced
Solution Approach 1:
The patent introduces active brightness variation as an intermediary metric between raw sensor readings and final depth values. Instead of directly analyzing complex multipath interference patterns or motion blur effects, the system uses AB variation across frequencies as a simplified mediator to identify corrupted pixels. This intermediary approach reduces processing complexity compared to direct analysis of the underlying physical phenomena.
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 technique improves the quality of depth images by accurately removing sensor readings affected by motion blur and multipath interference, resulting in more reliable depth values.
Implementation Method 1
receiving instances of radiation having plural respective frequencies, each instance of radiation having a given frequency, originating from an illumination source, and being reflected from an environment
Data Source
AI summary
A computer-implemented technique is described herein for invalidating pixels in a time-of-flight depth-sensing device based on active brightness (AB) measurements. In one implementation, the technique involves, for each sensing element of a sensor: generating frequency-specific sensor readings in response to receiving instances of radiation having plural frequencies (e.g., frequencies f1, f2, and f3); generating a set of active brightness measurements (ABf1, ABf2, and ABf3) associated with the respective frequencies; generating a variation measure that reflects an extent of variation within the set of active brightness measurements; and invalidating a pixel associated with the particular sensing element if the variation measure satisfies a prescribed invalidation condition.