Structured Light Illumination Intensity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Structured illumination techniques face challenges in recovering three-dimensional position information of objects with varying distances and reflectivity due to limited dynamic range in camera setups, leading to image saturation and blooming, which degrades image quality and prevents accurate depth determination.
Innovation Solution
A depth camera assembly with a structured light source, liquid crystal array, and polarizer that dynamically adjusts the illumination intensity by controlling the polarization of structured light patterns to prevent saturation, allowing for wider dynamic range and accurate depth information retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structured illumination is used to illuminate the entire scene uniformly, then three-dimensional information can be recovered for objects in the scene, but image saturation and blooming occur for objects with high reflectivity or close distance, degrading image quality
Solution Approach 1:
The patent applies local quality by varying the illumination intensity across different spatial regions of the scene. The structured light pattern is modulated such that different portions of the scene receive different illumination intensities, allowing close/high-reflectivity objects to receive lower intensity (preventing saturation) while distant/low-reflectivity objects receive higher intensity (ensuring sufficient signal for depth recovery).
Solution Approach 2:
The patent implements dynamic control of illumination intensity through temporal modulation. The system dynamically adjusts the intensity of structured light projection based on detected saturation levels in real-time, switching between different illumination intensity states to prevent saturation while maintaining adequate signal strength for depth measurement across varying scene conditions.
2Measurement precision
If high illumination intensity is used to capture distant or low reflectivity objects, then sufficient signal for depth recovery is obtained, but close or high reflectivity objects become saturated
Solution Approach 1:
The system applies different illumination intensities to different spatial regions corresponding to different depth ranges. Distant regions receive higher illumination intensity to ensure sufficient reflected signal reaches the sensor, while close regions receive lower intensity to prevent saturation, thereby maintaining reliable image quality across the entire depth range of the scene.
Solution Approach 2:
The patent employs periodic modulation of illumination intensity with multiple temporal states. The system cycles through different illumination intensity levels, capturing images at each state, and combines these measurements to recover depth information for objects across the full dynamic range, effectively addressing both distant and close objects without saturation.
3Device complexity
If uniform illumination is applied across the scene, then the system structure remains simple, but the dynamic range is limited and cannot accommodate objects with varying distances and reflectivity
Solution Approach 1:
The patent introduces dynamic control mechanisms that allow the illumination system to adapt its intensity distribution in real-time. Through temporal modulation and spatially-varying intensity control, the system achieves wide dynamic range capability without requiring multiple physical light sources, maintaining relatively simple device structure while greatly enhancing adaptability to varying scene conditions.
Solution Approach 2:
The system changes the illumination parameter (intensity) dynamically across different spatial and temporal dimensions. By modulating the intensity parameter of the structured light source according to scene depth and reflectivity characteristics, the system expands its effective dynamic range while maintaining a unified illumination device, avoiding the need for complex multi-source configurations.
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
The solution effectively eliminates saturation and blooming, enabling the capture of high-quality images that can determine depth information for both close and distant objects with varying reflectivity, improving the accuracy and reliability of three-dimensional position determination.
Implementation Method 1
The liquid crystal array is positioned in front of the SL element and is capable of changing a polarization of portions of the structured light pattern generated by the SL element
Implementation Method 2
The polarizer is positioned in front of the liquid crystal array and attenuates portions of the light pattern based on the polarization of the portions of the light pattern
Data Source
AI summary
A depth camera assembly (DCA) determines depth information for a scene in a field of view of the DCA. The DCA includes a structured light (SL) illuminator, a camera, and a controller. The SL illuminator includes a source assembly, a SL element, a liquid crystal (LC) array, and a polarizer. The source assembly generates light, and the SL element generates a SL pattern using the generated light source. The LC array includes a plurality of addressable cells configured to polarize the SL pattern in accordance with adjustment instructions. The polarizer attenuates portions of the SL pattern based on the polarization of the portions of the SL pattern. The camera captures an image of the SL pattern, and the controller identifies portions of the image that are saturated and generates adjustment instructions based in part on the identified portions of the image, and provides the adjustment instructions to the LC array.