Depth Image Generation Using PN Sequence Modulation
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Solution Overview
Problem
Existing depth image capture methods face interference issues when multiple cameras capture images of objects at close distances due to infrared light sources causing errors in depth extraction results.
Innovation Solution
An apparatus and method utilizing pseudorandom (PN) sequences with different time shifts for optical modulation of reflective light, allowing for accurate depth image generation by sampling intensity images from an optical sensor, thereby reducing interference between multiple users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If infrared light sources are projected from multiple cameras to capture depth images simultaneously, then depth information can be obtained for multiple objects, but interference occurs between the light sources causing errors in depth extraction results
Solution Approach 1:
The patent segments the light source modulation by assigning different pseudorandom sequences to different cameras. Each camera's infrared light source is modulated with a unique PN sequence, allowing the optical sensor to distinguish between light from different cameras through correlation processing. This segmentation of the light source signal enables multiple cameras to operate simultaneously without mutual interference, resolving the contradiction between multi-camera productivity and measurement precision.
Solution Approach 2:
The patent changes the temporal parameter of the light source by introducing time shifts to the pseudorandom sequences used by different cameras. Each camera uses a PN sequence with a distinct time offset, creating unique temporal signatures for each light source. This parameter change in the time domain allows the receiving end to differentiate between simultaneous light sources through cross-correlation, maintaining depth extraction accuracy while enabling multi-camera simultaneous operation.
2Measurement precision
If pseudorandom sequences with time shifts are used to modulate light from multiple cameras, then interference between cameras is reduced, but the complexity of the modulation and demodulation process increases
Solution Approach 1:
The patent uses pseudorandom sequences that are easily generated and replicated through digital logic circuits. The same PN sequence structure is copied and distributed to multiple cameras, with only the time shift parameter varied. This copying approach allows complex modulation functionality to be achieved using simple, repeatable digital patterns rather than requiring complex hardware modulation circuits, thus reducing overall system complexity while maintaining measurement precision.
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 reduces depth extraction errors by using PN sequences with time shifts to modulate light, enabling precise depth image generation even in multi-camera scenarios, improving accuracy and reducing interference.
Implementation Method 1
an optical modulator which optically modulates reflective light which is reflected light from an object to which light modulated using a first pseudorandom (PN) sequence is irradiated, by use of second PN-sequences
Implementation Method 2
an optical sensor which senses the optically modulated reflective light
Data Source
AI summary
An apparatus and method for generating a depth image are provided. The apparatus includes an optical modulator, an optical sensor, and a depth image processor. The optical modulator optically modulates light which is reflected from an object to which light modulated using a first pseudorandom (PN) sequence is irradiated. The optical modulator optically modulates the reflected light using second PN-sequences, where each of the second PN-sequences has a same PN sequence as the first PN-sequence, but the second PN-sequences have N different time shifts. The optical sensor senses the optically modulated reflective light. The depth image processor samples N intensity images from the optically modulated reflective light sensed by the optical sensor and generates a depth image of the object using the sampled N intensity images.