Phosphorescent Paint Motion Capture Shutter Synchronization
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Solution Overview
Problem
Traditional motion capture systems face limitations in capturing detailed facial expressions and body motion due to the reliance on discrete markers and low contrast between reflective markers and the environment, leading to reduced accuracy and increased complexity in data processing.
Innovation Solution
The use of phosphorescent paint and synchronized shutter control in cameras to capture high-contrast images of predefined curve patterns on a performer's face, allowing for more efficient data collection and improved surface data generation by differentiating between lit and glow frames, thereby enhancing motion capture accuracy and simplifying data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional retro-reflective markers are used in optical motion capture systems, then the system can capture motion data, but the contrast between markers and environment is low leading to reduced measurement precision
Solution Approach 1:
The patent uses phosphorescent paint that changes its light emission characteristics based on excitation. The paint absorbs light from LEDs and emits it with a distinct color signature, creating high contrast against the environment. This color-changing property allows the system to differentiate the markers from ambient light sources, resolving the contradiction between measurement precision and environmental interference.
Solution Approach 2:
The phosphorescent paint acts as an intermediary between the LED light sources and the camera sensors. It absorbs the LED light and re-emits it as phosphorescent radiation, which has distinct spectral characteristics. This intermediary conversion process creates a clear signal that is easily distinguishable from environmental light, improving measurement precision while reducing interference.
2Loss of information
If discrete markers are used for motion capture, then motion tracking is possible, but detailed facial expressions and body motion cannot be captured leading to loss of information
Solution Approach 1:
The patent applies phosphorescent paint to specific regions of the performer's body and face, creating localized high-contrast markers. By strategically placing the paint in areas where detailed motion occurs (face, hands, feet), the system captures rich information about facial expressions and body motion without requiring complex discrete marker placements throughout the entire body.
Solution Approach 2:
The phosphorescent paint creates a visual copy of the performer's motion that is directly captured by the cameras. Unlike discrete markers that require complex tracking algorithms, the paint provides a continuous, high-contrast visual record of motion that can be directly analyzed to extract detailed facial expressions and body movement information.
3Illumination intensity
If continuous illumination is used for motion capture, then the performer can see the environment, but the contrast between markers and environment is reduced
Solution Approach 1:
The system uses periodic illumination with LEDs synchronized to the camera shutter. The LEDs are turned on during the exposure period, providing brief but intense illumination that excites the phosphorescent paint. This periodic action creates a clear signal during the short exposure window while allowing the performer to see the environment during other times, resolving the contradiction between illumination intensity and marker visibility.
Solution Approach 2:
The phosphorescent paint undergoes a phase transition in its light emission properties when excited by LED light. It absorbs energy during the LED on-period and then emits phosphorescent radiation during the exposure period. This phase transition from absorbed to emitted state creates high contrast visibility during the critical measurement window while maintaining environmental visibility during non-exposure periods.
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 significantly improves motion capture efficiency by providing high contrast and continuous illumination, enabling precise tracking of facial expressions and body motion with reduced environmental interference and increased accuracy in data representation.
Implementation Method 1
applying phosphorescent paint to specified regions of a performer's face and/or body; strobing a light source on and off, the light source charging the phosphorescent paint when on
Implementation Method 2
the markers 101, 102 are passive spheres comprised of retro-reflective material, i.e., a material which reflects light back in the direction from which it came
Data Source
AI summary
A method is described comprising: applying phosphorescent paint to specified regions of a performer's face and/or body; strobing a light source on and off, the light source charging the phosphorescent paint when on; and strobing the shutters of a first plurality of cameras synchronously with the strobing of the light source to capture images of the phosphorescent paint, wherein the shutters are open when the light source is off and the shutters are closed when the light source is open.