Motion Detection Using Fresnel Lens Masking

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Solution Overview

Problem

Existing motion detection systems in video rely heavily on accurate background image estimation, which can be complicated and prone to errors due to scene changes, repetitive movements, and lighting variations, leading to incorrect foreground extraction.

Innovation Solution

A system utilizing a Fresnel lens and PIR sensor with a lens pattern to detect motion by capturing raw images, differentiating frames to obtain a motion image, and masking it with positive and negative areas to calculate a motion image response value, triggering an alarm if the value exceeds a predetermined threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If foreground extraction techniques are used for motion detection, then motion can be detected, but the system becomes complicated and requires memory storage space for background image

Engineering Contradiction:

Improvemotion detection accuracyVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential motion detection function from the complex background estimation and foreground extraction process. By using a simplified differential method that compares current frame with previous frame, it removes the need for storing and maintaining background images, thereby reducing system complexity while preserving motion detection capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of estimating background and subtracting it to find foreground (traditional approach), the patent inverts the approach by directly computing the difference between consecutive frames. This inversion eliminates the need for background modeling and complex foreground extraction algorithms, simplifying the system architecture

Inventive Principle:

Principle #13The other way round (Inversion)

2Duration of action of stationary object

If background image is selectively updated by adding new pixels, then background image can be maintained, but incorrect classification causes incorrect updating and problems with foreground extraction

Engineering Contradiction:

Improvebackground image validityVSAvoidforeground extraction accuracy

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent replaces the complex mechanical process of background image updating and pixel classification with a simpler differential calculation approach. By computing frame differences directly, it eliminates the need for pixel-by-pixel classification and background model maintenance, reducing errors from incorrect classification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the parameter used for motion detection from background-foreground separation to frame-to-frame difference. This parameter change transforms the problem from one requiring accurate background estimation to one that directly measures motion through temporal differences, improving reliability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If long-term scene changes or high frequency repetitive movement is present, then background image identification becomes problematic, but motion detection is still needed

Engineering Contradiction:

Improvemotion detection reliabilityVSAvoidhandling scene changes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent uses periodic frame differencing, continuously comparing current frame with previous frame. This periodic action allows the system to adapt to changing scenes naturally, as each frame difference calculation is independent and does not rely on long-term background assumptions, enabling reliable motion detection even with scene changes or repetitive movements

Inventive Principle:

Principle #19Periodic action

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 effectively detects motion without relying on background image estimation, reducing errors and handling scene changes and lighting variations, enabling reliable motion detection in dynamic environments.

Implementation Method 1

employ a PIR sensor and a lens pattern associated therewith to detect intrusion. In accordance with disclosed embodiments, a Fresnel lens can be placed in front of a PIR sensor monitoring a region

Methodology Applied

Scientific EffectFresnel lens: Fresnel Lens

Implementation Method 2

a Fresnel lens can be placed in front of a PIR sensor monitoring a region

Methodology Applied

Scientific EffectInfrared radiation detection: Infrared Radiation

Data Source

PatentUS10311690B2Systems and methods for detecting motion based on a video pattern

Publication Date: 2019.06.04 RESIDEO USA LLC

AI summary

Some systems and methods for detecting motion based on a video pattern can include creating a motion image from a sequence of raw images, masking the motion image with a lens pattern associated with a PIR sensor and an associated Fresnel lens, splitting each of a plurality of blocks of the lens pattern into first and second negative areas, identifying a positive area pixel value as a sum of all pixels in the motion image aligned with the first positive area in the plurality of blocks, identifying a negative area pixel value as a sum of all pixels in the motion image aligned with the second negative area in the plurality of blocks, identifying a motion image response value as a difference between the positive and negative area pixel values, and identifying a presence of motion when the motion image response value exceeds a predetermined value.