Single shot laser speckle based 3D acquisition system for medical applications

3D digital models of the upper limb anatomy represent the starting point for the design process of bespoke devices, such as orthoses and prostheses, which can be modeled on the actual patient’s anatomy by using CAD (Computer Aided Design) tools. The ongoing research on optical scanning methodologies has allowed the development of technologies that allow the surface reconstruction of the upper limb anatomy through procedures characterized by minimum discomfort for the patient. However, the 3D optical scanning of upper limbs is a complex task that requires solving problematic aspects, such as the difficulty of keeping the hand in a stable position and the presence of artefacts due to involuntary movements. Scientific literature, indeed, investigated different approaches in this regard by either integrating commercial devices, to create customized sensor architectures, or by developing innovative 3D acquisition techniques. The present work is aimed at presenting an overview of the state of the art of optical technologies and sensor architectures for the surface acquisition of upper limb anatomies. The review analyzes the working principles at the basis of existing devices and proposes a categorization of the approaches based on handling, pre/post-processing effort, and potentialities in real-time scanning. An in-depth analysis of strengths and weaknesses of the approaches proposed by the research community is also provided to give valuable support in selecting the most appropriate solution for the specific application to be addressed.

Section: 3d Scanning Technologiesmentioning

confidence: 99%

Sensor Architectures and Technologies for Upper Limb 3D Surface Reconstruction: A Review

Paoli

Neri

Razionale

et al. 2020

“…Fenghui et al showed that the Shi-Tomasi method was a more reliable and faster feature detector than other methods for moving IR camera applications [45]. Therefore, for efficient feature detection of the blurred image, we used the Shi and Tomasi corner detection method [46,47], which is an extension of the Harris corner detection method [48]. First, the sum of squared differences (SSD) is calculated using the sliding window approach.…”

Section: Background Trackingmentioning

confidence: 99%

Global Motion-Aware Robust Visual Object Tracking for Electro Optical Targeting Systems

Kim

Lukežič

Lee

et al. 2020

Self Cite

Although recently developed trackers have shown excellent performance even when tracking fast moving and shape changing objects with variable scale and orientation, the trackers for the electro-optical targeting systems (EOTS) still suffer from abrupt scene changes due to frequent and fast camera motions by pan-tilt motor control or dynamic distortions in field environments. Conventional context aware (CA) and deep learning based trackers have been studied to tackle these problems, but they have the drawbacks of not fully overcoming the problems and dealing with their computational burden. In this paper, a global motion aware method is proposed to address the fast camera motion issue. The proposed method consists of two modules: (i) a motion detection module, which is based on the change in image entropy value, and (ii) a background tracking module, used to track a set of features in consecutive images to find correspondences between them and estimate global camera movement. A series of experiments is conducted on thermal infrared images, and the results show that the proposed method can significantly improve the robustness of all trackers with a minimal computational overhead. We show that the proposed method can be easily integrated into any visual tracking framework and can be applied to improve the performance of EOTS applications.

“…The abovementioned methods work well for scattering materials, including industrial materials such as rubber, metal and unpolished glass, and even biological tissues such as bones and vessels. Moreover, because only one frame of an image is necessary, the above methods all have potential use for dynamic measurement [25][26][27]. For an optical surface after a good polish, if no modification is allowed to the surface for protection, minimal scattering occurs and nearly no speckle can be generated on the surface under test (SUT) only with laser illumination.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Deformation Measurement of Specular Surface with Deflectometry and Speckle Digital Image Correlation

Wang

Cheng

et al. 2020

The deformation measurement of a specular surface is of great importance during the quality inspection and installation of optical elements or wafers, especially those with large apertures. We propose a deflectometry method with speckle digital image correlation (DeSDIC) to realize the dynamic and high-accuracy measurement of the deformation on specular surfaces, with a simple system structure and robustness to noises and environmental vibrations. Random speckle pattern displayed on liquid crystal display is reflected by the original surface under test (SUT), and the distorted pattern is recorded by a camera. This originally distorted pattern is taken as the reference image, and the patterns captured afterwards are digitally correlated with the reference image to calculate the gradient change and deformation of the SUT. The theoretical relationships and an experimental one-step calibration scheme are proposed. Both static and dynamic deformations of a deformable mirror were experimentally measured to demonstrate the feasibility and accuracy of DeSDIC, which is comparable to phase-measuring deflectometry and interferometry.