Time-Coded Illumination Depth Mapping via Per-Pixel Digital Subtraction
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Solution Overview
Problem
Existing 3D mapping techniques require substantial computing resources for correlation computations to find pixel shifts, limiting spatial resolution and efficiency.
Innovation Solution
The use of time-coded illumination in combination with an image sensor that decodes time coding at each pixel, allowing for digital shift values to be determined through digital subtraction, eliminating the need for complex computations and achieving higher spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correlation computations are used to find pixel shifts in existing 3D mapping techniques, then depth mapping functionality is achieved, but substantial computing resources are required and spatial resolution is limited
Solution Approach 1:
The patent applies preliminary action by encoding temporal information into the illumination pattern before projection. The illumination assembly projects patterns with built-in time coding that allows the image sensor to directly decode shift values through simple digital subtraction, eliminating the need for complex post-capture correlation computations. This preliminary encoding of measurement information in the illumination pattern resolves the contradiction by enabling high spatial resolution through simple per-pixel operations rather than resource-intensive global computations.
Solution Approach 2:
The patent substitutes complex computational mechanics with simpler optical and digital processing. Instead of using substantial computing resources for correlation computations, the system replaces this with time-coded illumination patterns and per-pixel digital subtraction operations. The computational problem is transformed into an optical encoding problem, where the illumination pattern itself carries the measurement information, and the sensor performs simple decoding through subtraction rather than complex correlation algorithms.
2Measurement precision
If complex correlation computations are performed to achieve accurate pixel shift measurement, then depth mapping accuracy is improved, but processing time and computational load increase substantially
Solution Approach 1:
The illumination pattern is pre-encoded with temporal information that enables direct calculation of pixel shifts. By embedding time codes in the illumination sequence, the system allows the image sensor to determine shifts through simple per-pixel subtraction operations rather than performing time-consuming correlation computations. This preliminary encoding of shift information in the illumination pattern achieves both high measurement accuracy and fast processing by moving the computational burden to the illumination generation stage rather than the image processing stage.
Solution Approach 2:
The patent changes the parameter encoding approach from spatial correlation to temporal coding. Instead of using complex spatial correlation computations to extract shift information, the system transforms the problem by encoding temporal sequences into the illumination patterns. This parameter transformation allows the sensor to decode pixel shifts through simple temporal comparison (digital subtraction) rather than complex spatial correlation, thereby reducing processing time while maintaining measurement accuracy.
3Measurement precision
If standard illumination patterns are projected onto the object, then the imaging system remains simple, but accurate digital shift values cannot be obtained without complex computations
Solution Approach 1:
The illumination assembly performs preliminary encoding by projecting patterns with embedded time codes rather than standard static patterns. This preliminary action embeds measurement information directly into the illumination sequence, allowing the image sensor to extract accurate digital shift values through simple per-pixel subtraction operations. The complexity is shifted to the illumination generation stage, where time-coded patterns are created, but this enables the imaging side to remain relatively simple while achieving high measurement precision.
Solution Approach 2:
The time-coded illumination pattern acts as an intermediary that carries measurement information from the illumination source to the image sensor. Instead of directly measuring shifts from standard patterns through complex computation, the system introduces time-coded patterns as an intermediary medium that encodes shift information in its temporal structure. This intermediary encoding layer enables accurate shift measurement through simple decoding operations at the sensor, resolving the contradiction between measurement precision and device complexity.
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 simplifies the process of generating 3D maps by providing accurate digital shift values for each pixel, enhancing spatial resolution and reducing computational requirements, enabling efficient 3D mapping with lower hardware demands.
Implementation Method 1
an illumination assembly (30) configured to project a time-coded pattern of optical radiation onto an object (28)
Implementation Method 2
An image capture assembly (38) captures an image of the pattern on the object
Implementation Method 3
a processor (46) generates a depth map of the object from the image data captured by the image capture assembly
Data Source
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AI summary
A method for depth mapping includes illuminating an object with a time-coded pattern and capturing images of the time-coded pattern on the object using a matrix of detector elements. The time-coded pattern in the captured images is decoded using processing circuitry embedded in each of the detector elements so as to generate respective digital shift values, which are converted into depth coordinates.