Visible-Thermal Face Temperature Measurement With Distance Compensation
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Solution Overview
Problem
Thermal radiation attenuation with distance leads to inaccurate temperature determination of subjects in thermal images, necessitating a method to account for distance in temperature calculation.
Innovation Solution
A system that combines visible and thermal imaging to determine subject distance and temperature, using visible image features to correct thermal image temperature readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal imaging is used to determine subject temperature, then temperature measurement capability is provided, but measurement precision deteriorates as distance increases due to thermal radiation attenuation
Solution Approach 1:
The patent introduces visible light imaging as an intermediary to establish distance information between the thermal imaging device and the subject. By using the visible image to calculate distance (through reference objects or face recognition), the system obtains a mediator parameter that compensates for thermal radiation attenuation, thereby improving temperature measurement accuracy without requiring the device to be close to the subject.
2Measurement precision
If thermal radiation attenuation is compensated for distance, then temperature accuracy is improved, but device complexity increases due to multiple imaging systems and processing requirements
Solution Approach 1:
The patent merges visible light imaging and thermal imaging functions into a single integrated device. Both imaging units share the same housing and coordinate system, allowing the system to capture both visible and thermal images simultaneously or sequentially. This merging reduces overall system complexity compared to using separate devices, while still enabling distance-based temperature compensation.
Solution Approach 2:
The visible imaging unit serves multiple functions: it captures visible images for distance calculation, provides reference objects for scaling, and enables face recognition for precise subject identification. This multi-functionality reduces the need for additional specialized components, thereby managing system complexity while achieving accurate temperature measurement.
3Measurement precision
If distance calculation is performed using visible image reference objects, then temperature determination accuracy is improved, but measurement capability is lost when reference objects are not visible or identifiable
Solution Approach 1:
The patent uses face recognition to create a digital copy or model of the subject's face from the visible image. This face model serves as a new reference object that can be reliably identified and measured even when traditional reference objects are not visible. The face coordinates and dimensions are extracted to calculate distance, ensuring measurement capability is maintained across various conditions.
Solution Approach 2:
The system dynamically changes the reference parameter used for distance calculation based on availability. When standard reference objects are not visible or identifiable in the scene, the system switches to using face recognition parameters (face coordinates, face dimensions) as the new reference. This parameter substitution maintains adaptability and ensures continuous measurement capability.
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
Accurately determines subject temperature by considering distance, enabling simultaneous temperature measurement of multiple subjects without fixed positioning, improving efficiency and accuracy.
Implementation Method 1
A temperature of a subject (e.g., a person) may be determined based on gray values associated with the subject in a thermal image acquired by a thermal capture device (e.g., a thermal camera). However, thermal radiation of the subject may be attenuated as a distance between the thermal capture device and the subject increases
Data Source
AI summary
The present disclosure may provide a temperature determination system. The temperature determination system may obtain a visible image including at least one subject and a thermal image from an image capture device. For each of the at least one subject, the temperature determination system may determine first location information associated with a face of the subject in the visible image and determine a distance between the subject and the image capture device based on the visible image. The temperature determination system may also determine second location information associated with the face in the thermal image based on the first location information associated with the face. The temperature determination system may determine a temperature of the subject based on the second location information associated with the face and the distance between the subject and the image capture device.