Opto-electronic Sensor Depth Mapping via Spectral Segmentation
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Solution Overview
Problem
Conventional three-dimensional surveillance systems, particularly passive stereo systems, face challenges in generating reliable depth maps in low-contrast or unstructured environments, leading to potential undetected hazards due to errors in distance calculation, while active systems struggle with ambient light interference.
Innovation Solution
The optoelectronic sensor evaluates light from the detection area multiple times by separating different light components and recording them on distinct paths, allowing for the combination of active and passive stereoscopy to generate improved depth maps through mutually compensating distance information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive stereo systems are used for three-dimensional surveillance, then the system can operate without additional illumination equipment, but the detection reliability deteriorates in low-contrast or unstructured environments leading to gaps in depth maps
Solution Approach 1:
The patent combines passive stereo imaging with active structured light illumination in a single integrated system. The passive stereo cameras capture both naturally lit scene information and projected pattern information simultaneously, merging the advantages of both approaches to achieve reliable depth mapping in various lighting conditions without requiring separate systems
Solution Approach 2:
The system dynamically adjusts the illumination pattern parameters (such as pattern density, frequency, and intensity) based on ambient light conditions and scene characteristics. This allows the active illumination to provide sufficient structure information in low-contrast environments while remaining invisible or minimal in well-lit conditions, thus adapting the system behavior to different operational contexts
2Measurement precision
If active structured light illumination is used to generate reliable depth information, then dense and accurate depth maps can be created, but the system becomes vulnerable to ambient light interference especially in direct sunlight
Solution Approach 1:
The patent segments the captured light into different wavelength components using optical filters. The active structured light is projected at specific wavelengths that are filtered out for the passive stereo cameras, while the passive cameras capture ambient light in complementary wavelength ranges. This spectral segmentation allows both active and passive imaging to operate simultaneously without mutual interference
Solution Approach 2:
The system uses temporally modulated illumination patterns that are switched on and off at specific frequencies. By synchronizing the illumination modulation with the camera exposure timing, the system can isolate the active pattern signal from ambient light through temporal filtering, effectively rejecting continuous ambient illumination while capturing the modulated pattern information
3Device complexity
If two-dimensional camera systems are used for surveillance, then the system structure remains simple, but the ability to distinguish permitted object movements from inadmissible interventions deteriorates
Solution Approach 1:
The patent extends two-dimensional image capture into three-dimensional space by incorporating passive stereo vision and active structured light depth mapping. This adds the depth dimension (Z-axis) to the traditional two-dimensional (X-Y plane) surveillance, enabling the system to distinguish between objects at different distances and classify movements based on their spatial trajectory and depth information
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 results in significantly more reliable monitoring by creating dense and accurate depth maps, enhancing safety applications by reducing errors in distance calculations and improving system robustness across varying ambient light conditions.
Implementation Method 1
a beam splitter element which separates light from the detection area into different light paths depending on their frequency, in that the beam splitter element deflects light into a first light path for a first frequency band and light into a second light path for a second frequency band
Data Source
Figure 1~2
Figure 3
AI summary
The sensor (10) has light paths (20a, 20b, 120a, 120b) in which image sensors (22a, 22b, 122a, 122b) e.g. charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) sensors, are provided, respectively. Beam splitter elements (18, 118) e.g. coated prism or mirror, selectively deflect incident lights (12a, 12b, 112a, 112b) under presetting physical characteristics of the lights in the paths. A three-dimensional evaluation unit (24) generates two sets of displacement information using two sets of image data of a spatial area (14) recorded by the image sensors, respectively. An independent claim is also included for a method for monitoring a spatial area.