Aesthetic reconstruction of microtia: a review of current techniques and new 3D printing approaches

Three dimensional (3D) printing and biofabrication technologies are revolutionising medicine with low-cost and novel treatments for complex medical conditions. These approaches differ from traditional treatments by using 3D scanning, computer modelling and 3D printing to automate the production of patient-specific tissue replacement or prostheses using a wide range of materials. One area impacted by this technology is the treatment of congenital maxillofacial conditions such as microtia, a condition affecting the intrauterine development of the auricle (external ear) and with a prevalence of 2.06 cases for every 10,000 births. While not life-threatening, microtia significantly impacts the emotional and psychological well-being of the affected child and their parents. Current treatments include the use of prosthetic ears or surgical methods such as autografting rib cartilage or alloplastic implants. Although current options have shown documented success, they are highly dependent on the surgeon’s skill and it has been demonstrated that poor quality solutions can further exacerbate negative psychosocial impacts. As such, higher quality, lower cost and more customised options would be welcomed by patients and parents alike. Recent advances in 3D scanning, modelling and printing techniques could significantly benefit the treatment and reconstructive options for children with microtia, leading to improved quality of life.     

A 12-camera body scanning system based on close-range photogrammetry for precise applications

A precise 3D body scanning system, designed for applications in the medical and biomedical field, is described. The system consists of 12 digital cameras, mounted on a rigid frame which maintains the B/H ratio constant. An LED lighting system, integrated with the rigid frame, ensures a homogenous illumination of the subject. A modified firmware installed on each device enables the synchronised remote release driven by remote control. Data transmission to the computer is carried out wirelessly. A process for the estimation of the extrinsic camera parameters has been implemented with the aim of obtaining a 3D model in 1:1 scale. Analyses have been performed in order to state the repeatability of the process used to estimate the external camera calibration parameters as well as the precision of the 3D digital models of a body obtained for a mannequin and for a live human subject.     

3D scanning and geometry processing techniques for customised hand orthotics: an experimental assessment

In the field of rehabilitation, the 3D scanning of body parts can be considered a crucial starting point for subsequent 3D model design of customised devices, especially when additive manufacturing techniques are involved in their production. This study experimentally evaluates and identifies appropriate procedures to acquire and process 3D anatomic images of the hand, including fingers, for the design of customised orthoses. Hand scanning is a complex activity and requires solutions capable of solving problematic aspects, such as the difficulty in maintaining the hand in a steady position and the presence of motion artefacts due to involuntary movements. We addressed such issues by considering the use of two different kinds of optical scanning device. The acquisition process has been initially defined based on healthy subjects and then extended to patients affected by pathologies that compromise upper limb functionality. Quality anatomical models were produced thanks to the application of advanced geometry processing technologies for the automated alignment of multiple scans and the removal of artefacts due to involuntary movements. As a result, with distinctive pros and cons, both the proposed combinations of scanning procedures and dedicated geometry processing evidenced their suitability in producing complete and accurate enough 3D models to be exploited for the subsequent design and production of customised hand orthoses in a typical reverse engineering pipeline.     

用于机器人视觉的大景深便携式三维扫描系统

针对机器人视觉对便携式三维扫描系统的大景深要求,利用Scheimpflug条件对CCD平面进行偏转,成功地将扫描系统的景深从30mm提高到了100mm以上;并根据CCD偏转后的摄像机模型,在理论上完整地推导了便携式集成三维扫描系统的物像关系方程。针对景深扩大后带来的测量精度降低的问题,提出了一种对系统全景深范围进行分段校准的新方法,提高了测量精度与系统分辨率。三维重建时,根据被扫描物体所对应的图像点在像平面上的不同位置分别调用不同的标定参数将二维图像坐标转变为物体的空间坐标,测量精度可以达到0.06mm。     

Research on adaptive scanning and quantisation for 3D DCT video coding

Abstract

Nowadays, a well-established video coding method is based on the block-matching algorithm that is in the core of all MPEG and H.26x standards. However, this method involves motion estimation and compensation; thus the computational complexity is high. However, the video coding based on three-dimensional discrete cosine transform (3D DCT) is a potential method, and the scanning order and quantisation of 3D DCT coefficients play a crucial role in coding effect. So, the statistical performances of 3D DCT are studied in this paper, and then adaptive scanning order and quantisation of 3D coefficients are proposed. The theoretical analysis and experiment results show significant improvement in performance over previously reported methods.     

Coded targets and hybrid grids for photogrammetric 3D digitisation of human faces

The three-dimensional (3D) measure of the human body is currently performed using mostly optical technologies. One of the most cost effective non-contact techniques is photogrammetry; its main disadvantage is the lack of automation because the correspondences between the same points in different images must be taken manually. In this paper the authors present a properly designed low-cost photogrammetric system for 3D scanning of human faces. Results are compared projecting onto the faces patterns composed by coded targets and mixed coded-uncoded targets.     

Alpha-Shapes分段改进算法在三维模拟树枝体积扫描测量中的应用

针对树木与树枝分叉部分体积计算困难,三维扫描建模易产生黏连现象等问题,提出一种Alpha-Shapes分段改进算法.通过三维激光扫描技术获取三维模拟树枝的点云数据,利用Alpha-Shapes算法计算出三维模拟树枝的点云边缘轮廓并进行三维重建,利用分段算法对三维重建数据进行体积分割计算,通过点云最高层补偿以此保证分段算...     

Customised design and manufacture of protective face masks combining a practitioner-friendly modelling approach and low-cost devices for digitising and additive manufacturing

This project analyses the viability of an efficient modelling approach using a semi-automatic algorithm within a Computer Aided Design (CAD) application in combination with low-cost digitising devices and low-cost Additive Manufacturing (AM) printers when designing and manufacturing patient-specific face masks. The aims of the study were to enable clinical practitioners to utilise the advantages of three-dimensional (3D) scanning, CAD and AM without having to be trained to use design/engineering software. Face features were captured using two 3D devices. The resulting meshes were compared via the Hausdorff Distance method. A semi-automatic modelling procedure was developed with ‘Rhinoceros’ and ‘Grasshopper’ to model the face mask and customise several features. With that procedure, volunteers modelled a face mask in less than 30 minutes in their first attempt. The resulting virtual mask was manufactured with two AM printers. An initial economic study indicated that the presented approach offers a feasible alternative to the current practices.     

3D scanning data processing and registration for the construction of urban scenes via image methods

The difficulty of the 3D registration mainly lies in the huge computation for a precise alignment, especially for large data of urban scenes. In this paper, we proposed an algorithm that converts this 3D problem into 2D case. The main idea is to map the point cloud onto the image. Then, SIFT algorithm is adopted to detect the key points of the images, and key points from two images corresponding to the two point clouds ready to be registered are matched to form several pairs. Next, the key point pairs construct an intrinsic link between the images. From the one-to-one correspondence between pixel and point, this relation can be converted back to 3D space, according to which a transform matrix can be consequently established. The resultant matrix aims at guiding the spatial transform to achieve an ideal 3D registration. Later experiments illustrate that it will obtain a preferable result in much less time.     

GT9800特殊部位靶扫描探讨

我院于86年引进美国GE公司CT9800,经过近10年时间使用,探索和总结经验认为,该机虽属大型CT机,在计算机方面也具有优越性,如图像质量高,机器操作易掌握。但该机引进时图像处理系统只 有一套,重建图像速度较慢,虽经改装增加一套处理系统,但日常工作中仍存在重建图像时间长,病人等 候时间也长,无法满足工作要求.经过多年的工作积累了不少经验,充分开发该机的优越性,在进行特殊 部位的检查项目中,对靶扫描的方法进行大胆的改进,由原来的一次扫描两次特殊重建处理图像方法, 改为一次靶直接扫描,只进行一次特殊重建图像的步骤,不采用放大重建方法进行图像处理,克服了多 数靶放大扫描;遗漏病变的问题,保证图像的诊断要求,又缩短了该机重建图像时间,提高了工作效率。     

Past,Present, and Future of Soft-Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by synthetic polymers bringing about significant improvements in fabrication and greater realism and utility. These traditional methods have now been disrupted by the advanced manufacturing revolution, radically changing the materials, methods, and nature of prosthetics. In this report, traditional synthetic polymers and advanced prosthetic materials and manufacturing techniques are discussed, including a focus on prosthetic material degradation. New manufacturing approaches and future technological developments are also discussed in the context of specific tissues requiring aesthetic restoration, such as ear, nose, face, eye, breast, and hand. As advanced manufacturing moves from research into clinical practice, prosthetics can begin new age to significantly improve the quality of life for those suffering tissue loss or disfigurement.     

微细管道内表面光电检测及三维重构系统

基于位置传感器PSD和光学三角原理,开发了一种适于空间曲线型微细管孔内表面三维重构的检测系统.该系统主要由管道机器人、形貌检测器和曲率检测器等部分组成.形貌检测器可以采集管道内壁截面信息,并计算出截面环上的点在局部坐标系中的位置.曲率检测器负责测量管孔中心轴线在检测器采样位置处的局部几何性质,并完成管道中轴线的重构.在管道机器人的驱动下,根据上述两方面提供的数据以及其前进步距,可以实现管道内表面的三维重建.实验结果表明,利用该技术检测的管道时,管道曲率半径的相对检测精度可以达到±2%,内表面缺陷及内径的测量精度可以达到±0.1mm.     

Algorithms for the design of a multi-stage adaptive kanban system

The traditional kanban system with a fixed number of cards does not work satisfactorily in an unstable environment. With the adaptive kanban-type pull control mechanism, the number of kanbans is allowed to change with respect to the inventory and backorder level. It is required to set the threshold values at which cards are added or deleted, which is part of the design. Previous studies used local search and meta-heuristic methods to design an adaptive kanban system for a single stage. In a multi-stage system the cards are circulated within the stage and their presence at designated positions signals to the neighbouring stages details concerning the inventory. In this work, a model of a multi-stage system adapted from a traditional and adaptive kanban system is developed. A genetic and simulated annealing algorithm based search is employed to set the parameters of the system. The results are compared with a traditional kanban system and signs of improvement are found. The numerical results also indicate that the use of a simulated annealing algorithm produces a better solution.     

Analysis of irregular three-dimensional packing problems in additive manufacturing: a new taxonomy and dataset

With most Additive Manufacturing (AM) technology variants, build processes take place inside an internal enclosed build container, referred to as a ‘build volume’. It has been demonstrated that the effectiveness with which this volume is filled with product geometries forms an important determinant of overall process efficiency in AM. For effective operations management, it is important to understand not only the problem faced, but also which methods have proved effective (or ineffective) for problems with these characteristics in the past. This research aims to facilitate this increased understanding. The build volume packing task can be formulated as a three-dimensional irregular packing (3DIP) problem, which is a combinatorial optimisation problem requiring the configuration of a set of arbitrary volumetric items. This paper reviews existing general cutting and packing taxonomies and provides a new specification which is more appropriate for classifying the problems encountered in AM. This comprises a clear-cut problem definition, a set of precise categorisation criteria for objectives and problem instances, and a simple notation. Furthermore, the paper establishes an improved terminology with terms that are familiar to, but not limited to, researchers and practitioners in the field of AM. Finally, this paper describes a new dataset to be used in the evaluation of existing and proposed computational solution methods for 3DIP problems encountered in AM and discusses the importance of this research for further underpinning work.     

Estimation of biometric parameters from cattle rump using free-hand scanning and a 3D data processing algorithm

The quantity and quality of phenotypic data recovered from farm animals became a bottleneck for breeding programmes, and new tools are required to overcome this problem. This study evaluated the use of a portable structured light scanner and a 3D modelling to recover biometric information of the rump region in cattle. Virtual 3D models were created based on coordinates extracted from the points-cloud obtained through reverse engineering. A MATLAB algorithm was implemented to identify reference points, which were used to automatically calculate rump width, length, and angle. Results were compared to measurements performed directly in vivo and in the 3D models. There was no difference among rump parameter values obtained among biometry methods, though an interaction with body condition score was observed for rump width. The algorithm allowed evaluating correlations within biometric parameters, as well as extracting silhouettes of selected areas to evaluate differences caused by the mobilisation of subcutaneous fat.     

三维激光扫描技术在犯罪现场重建中的应用

目的:研究利用三维激光扫描技术进行现场重建的技术方法。方法:首先,利用三维激光扫描仪对现场进行扫描,获取现场的点云数据;然后,依据点云数据进行现场建模和动画模拟。结果:精确地重建了犯罪现场的场景并获得具有交互性、沉浸感的动画模拟效果。结论:利用三维激光扫描技术可以精确、方便地进行现场重建。     

3D重建对脑溢血容量计算的临床应用

笔者用3D重建法和手绘测量法，比较了30例脑溢血病人的CT图像，结果显示，利用3D重建法较精确的计算出脑溢血容量。     

涡轮叶片模具三维模型重构及误差分析

为了得到涡轮叶片模具制造误差量化分析结果,提出基于模型重构技术的误差检测方法。分别根据理论设计数据和实物测量数据建立了涡轮叶片模具的三维设计模型和实物模型,设计模型将为误差分析提供理论依据,通过两个模型配准和型面误差分析,得到量化制造误差。研究结果可用于类似的零件的数字化检测和误差分析。     

基于三维激光扫描技术的复杂采空区群爆破治理

针对露天矿山采空区群严重制约着生产平台的问题,为了消除采空区群带来的安全隐患,首先采用时效性强的C-ALS三维激光扫描仪精准探测,构建了3个采空区真实三维模型,揭示了受限采空区群的空间赋存关系;其次以爆破全生命周期精准设计为出发点,通过采用数码电子雷管精准控制起爆网路,最后充分利用边坡自由面及加大局部采空区侧的炸药单耗,有效地减小了岩层间的夹制作用。在大宝山露天多金属矿山661平台成功实施了强制爆破崩落处理,通过无人机多角度航拍及爆堆现场检查,发现爆区塌陷现象明显,充填率达90%,较好地消除了采空区群的不利影响,可为类似采空区治理提供参考。     

Manufacturing strategies for the ecosystem-based manufacturing system in the context of 3D printing

This paper aims to investigate the manufacturing strategies for the manufacturing systems in the context of 3D printing, referring to ecosystem-based manufacturing systems, rather than firm-based and network-based ones. A case study approach was adopted for this research, as the data was mainly collected via semi-structured interviews with staff members of companies in China. Besides the elements of strategic choices and manufacturing capabilities identified in the extant literature, this research verified three additional strategic choice elements (functional role, platform and solution) and identified two factors (platform openness and solution diversity) to classify an ecosystem-based manufacturing system. Meanwhile, four manufacturing capabilities of the ecosystem-based manufacturing system have been identified: collaborative manufacturing flexibility, rapid thriftiness ability, self-customisation and co-evolved design capability. The research results contribute to the area of manufacturing strategy via expanding its view from the firm and network levels to the ecosystem level. Meanwhile, the research results present operations managers with an understanding of the strategic choices and manufacturing capabilities of an ecosystem-based manufacturing system in the context of 3D printing.