Hybrid Phantom for Thermal and 3D Camera Calibration
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Solution Overview
Problem
There is a need to determine the relative position between a thermal camera and a 3D camera in medical applications, where existing methods lack effectiveness in calibrating these cameras accurately using a hybrid phantom that can be recognized by both thermal and 3D imaging systems.
Innovation Solution
A hybrid phantom with planar surfaces of high and low thermal emissivity is used, allowing the thermal camera to capture temperature differences and the 3D camera to generate a 3D point cloud, enabling the identification of marker surfaces and subsequent determination of the cameras' relative position through algorithms like Perspective-n-Points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hybrid phantom with specific thermal emissivity properties is used, then the measurement precision of camera calibration is improved, but the device complexity increases
Solution Approach 1:
The phantom incorporates regions with different thermal emissivity properties (high emissivity regions and low emissivity regions) to serve different detection purposes. The high emissivity regions appear bright in thermal images while low emissivity regions appear dark, creating distinct visual markers that can be easily identified by both thermal cameras and 3D cameras for accurate calibration.
Solution Approach 2:
The phantom is constructed using composite materials or surface treatments that provide contrasting thermal emissivity characteristics. This includes using materials with high thermal emissivity for certain regions and low thermal emissivity for other regions, allowing the same phantom structure to be detectable by both thermal imaging and optical 3D imaging systems simultaneously.
2Measurement precision
If markers with contrasting thermal emissivity are implemented, then the detection precision of marker locations is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The phantom design incorporates distinct regions with different thermal emissivity properties (high emissivity regions and low emissivity regions) to serve as markers. These regions create strong contrast in thermal images, making marker location detection highly precise even with moderate manufacturing tolerances.
Solution Approach 2:
The phantom uses thermal emissivity contrast analogous to color contrast - high emissivity regions appear bright while low emissivity regions appear dark in thermal images. This thermal 'color' differentiation provides clear visual markers that are easily detectable and locateable with high 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
This method allows for precise calibration of thermal and 3D cameras, enhancing the accuracy of medical procedures by establishing a reliable extrinsic parameter set for the camera pair, which is essential for precise positioning and monitoring in medical applications.
Implementation Method 1
The first camera is a thermal camera which captures a thermal image of the hybrid phantom... the first property involves having a high thermal emissivity of 0.8 or higher and the second property involves having a low thermal emissivity of 0.2 or less
Implementation Method 2
the second camera emits light onto the hybrid phantom and analyzes the reflected light, thus generating a 3D point cloud representing points on the surface of the hybrid phantom
Data Source
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AI summary
Use of a hybrid phantom for determining the relative position between a first camera and a second camera, wherein the first camera is a thermal camera which captures a thermal image of the hybrid phantom, the second camera emits light onto the hybrid phantom and analyzes the reflected light, thus generating a 3D point cloud representing points on the surface of the hybrid phantom, and the hybrid phantom has a planar surface comprising a background surface and a plurality of marker surfaces, wherein the background surface has one of a first property and a second property, each marker surface has the other one of the first property and the second property, the first property involves having a high thermal emissivity of 0.8 or higher and the second property involves having a low thermal emissivity of 0.2 or less, and wherein one of the first property and the second property further involves being diffuse reflective for the light emitted by the second camera, thus reflecting light emitted by the second camera back to the second camera.