Automatic balancing of 3D models

3D printing technologies allow for more diverse shapes than are possible with molds and the cost of making just one single object is negligible compared to traditional production methods. However, not all shapes are suitable for 3D print. One of the remaining costs is therefore human time spent on analyzing and editing a shape in order to ensure that it is fit for production. In this paper, we seek to automate one of these analysis and editing tasks, namely improving the balance of a model to ensure that it stands. The presented method is based on solving an optimization problem. This problem is solved by creating cavities of air and distributing dense materials inside the model. Consequently, the surface is not deformed. However, printing materials with significantly different densities is often not possible and adding cavities of air is often not enough to make the model balance. Consequently, in these cases, we will apply a rotation of the object which only deforms the shape a little near the base. No user input is required but it is possible to specify manufacturing constraints related to specific 3D print technologies. Several models have successfully been balanced and printed using both polyjet and fused deposition modeling printers.     

Dual‐color mixing for fused deposition modeling printers

In this work we detail a method that leverages the two color heads of recent low‐end fused deposition modeling (FDM) 3D printers to produce continuous tone imagery. The challenge behind producing such two‐tone imagery is how to finely interleave the two colors while minimizing the switching between print heads, making each color printed span as long and continuous as possible to avoid artifacts associated with printing short segments. The key insight behind our work is that by applying small geometric offsets, tone can be varied without the need to switch color print heads within a single layer. We can now effectively print (two‐tone) texture mapped models capturing both geometric and color information in our output 3D prints.     

Recursive symmetries for geometrically complex and materially heterogeneous additive manufacturing

We present a generative method for the creation of geometrically complex and materially heterogeneous objects. By combining generative design and additive manufacturing, we demonstrate a unique form-finding approach and method for multi-material 3D printing. The method offers a fast, automated and controllable way to explore an expressive set of symmetrical, complex and colored objects, which makes it a useful tool for design exploration and prototyping. We describe a recursive grammar for the generation of solid boundary surface models suitable for a variety of design domains. We demonstrate the generation and digital fabrication of watertight 2-manifold polygonal meshes, with feature-aligned topology that can be produced on a wide variety of 3D printers, as well as post-processed with traditional 3D modeling tools. To date, objects with intricate spatial patterns and complex heterogeneous material compositions generated by this method can only be produced through 3D printing.     

3D打印模型版权保护技术研究进展

目的 近年来3D打印模型的版权标注和保护引起了研究者的关注,为了全面反映3D打印模型版权保护研究的现状和最新进展,本文对国内外公开发表的主要文献进行了梳理和分析。方法 首先在广泛文献调研的基础上,描述3D打印模型文件和3D打印模型攻击类型,分析3D打印和扫描过程对模型的影响。然后对3D打印模型的版权保护策略进行分类,详细阐述每类方法的基本框架和相关技术特征。最后根据相关文献,将3D打印数字水印方法与传统网格水印算法和抗3D打印—扫描攻击的性能进行比较。结果 基于物理特性的3D模型版权保护技术能对3D打印后的模型嵌入有效的具有一定隐蔽性的版权标识,但在提取微结构体等信息时需要借助一些专用设备,不具有普适性。基于数字水印的方法既能抵抗传统的数字模态下的相似性变换、剪切、噪声、细分、量化、光顺等攻击,又能有效抵抗3D模型的数/模等模态转换攻击,并且高精度的3D打印机和扫描仪能有效提高水印的检测率。结论 3D打印产品是设计者和生产企业的智慧和心血的结晶,包含知识产权。随着3D打印在工业领域的广泛应用,3D打印模型版权保护有着广阔的应用前景和研究价值,但目前针对3D打印模型的版权保护的检测和评估机制存在一些局限性,未来需要构建统一的3D打印模型测试库和3D打印模型水印评测体系。     

基于多层次属性建模的云制造服务优选方法

随着云计算和信息技术的发展,制造企业逐渐由生产型向服务型转化.为了满足用户需求、解决云制造服务优选问题,提出一种基于多层次属性建模的云制造服务匹配和优选方法.对云制造服务资源和属性进行详细描述和划分,构建多层次属性描述模型.从基本属性、功能属性、非功能属性、综合匹配四个层次对候选服务和请求服务进行匹配计算.对不同类型的...     

面向云制造平台的模型修复算法及任务调度算法的研究

随着三维打印技术的发展,面向3D打印服务的云制造平台也得到快速发展,改变着传统的制造模式。然而目前的云制造平台也面临着诸多问题,针对目前存在的模型修复难度高及任务不能合理调度的问题,本文提出了保特征的模型修复算法和基于遗传算法的任务调度算法,并通过实验和仿真验证了算法的有效性。为了更好的体现算法效果,本文搭建了一个基于分布式制造的云制造平台,该平台配合模型自动修复算法以及基于遗传算法的任务调度算法,为用户提供低门槛、高效、优质的3D打印服务。     

Modeling of service agents for simulation in cloud manufacturing

Cloud Manufacturing is a paradigm of intelligent manufacturing system with information opening, resource sharing, and diversified services. In order to research the issues in cloud manufacturing, such as behaviors of a service provider and service consumer, matching of service, dynamic change of resource, verification of business model, scheduling of service and evolution of service network, cloud manufacturing simulation platform is widely applied. However, the method of simulation-based on agent or rule lacks to represent the characteristics of service in cloud manufacturing. This paper presents a method of integrating the service and agent to form a service agent. The service agent integrates intelligence to the service in cloud manufacturing so that it can trade autonomously and adapt itself to the environment. A simulation case of production takt is presented in the rear of the paper. It shows that the conceptual model of the service agent and the communication architecture of the service agent can build the service agent model, which can support the cloud manufacturing simulation platform.     

嵌入式Linux下基于ARM9的USB打印机控制器的设计

对Linux操作系统下的打印体系进行研究,分析并给出了嵌入式Linux下USB打印机控制器的软硬件设计.该打印机控制器基于S3C2440微处理器,采用MiniGUI实现了友好的人机交互界面,能识别多种USB打印机,完成中文文本文件以及各种格式图形文件的编辑和打印工作.     

Social Manufacturing for High-end Apparel Customization

Social manufacturing (SM), a novel distributed, collaborative and intelligent manufacturing mode, is proposed and developed for high-end apparel customization. The main components of SM cloud are designed, and its research topics are summarized. Then, SM's key technologies are studied. 3D technologies for apparel customization, like 3D modeling, 3D fitting mirror and 3D customization, are developed to improve the customization precision and user experience. Information based collaborative management is realized to share, communicate, and handle the information efficiently among all groups and individuals of SM cloud. Suppliers' evaluation mechanism is designed to support the optimal decisions making. Next, SM cloud is constructed in five layers for high-end apparel customization. By using SM cloud based crowd-sourcing, social resources can be allocated rationally and utilized efficiently, consumer can customize the product in any processes like innovation, design, making, marketing and service, and traditional apparel enterprise can be upgraded into SM mode for keeping it competitive in the future customization markets.      

三维视觉前沿进展

在自动驾驶、机器人、数字城市以及虚拟/混合现实等应用的驱动下,三维视觉得到了广泛的关注。三维视觉研究主要围绕深度图像获取、视觉定位与制图、三维建模及三维理解等任务而展开。本文围绕上述三维视觉任务,对国内外研究进展进行了综合评述和对比分析。首先,针对深度图像获取任务,从非端到端立体匹配、端到端立体匹配及无监督立体匹配3个方面对立体匹配研究进展进行了回顾,从深度回归网络和深度补全网络两个方面对单目深度估计研究进展进行了回顾。其次,针对视觉定位与制图任务,从端到端视觉定位和非端到端视觉定位两个方面对大场景下的视觉定位研究进展进行了回顾,并从视觉同步定位与地图构建和融合其他传感器的同步定位与地图构建两个方面对同步定位与地图构建的研究进展进行了回顾。再次,针对三维建模任务,从深度三维表征学习、深度三维生成模型、结构化表征学习与生成模型以及基于深度学习的三维重建等4个方面对三维几何建模研究进展进行了回顾,并从多视RGB重建、单深度相机和多深度相机方法以及单视图RGB方法等3个方面对人体动态建模研究进展进行了回顾。最后,针对三维理解任务,从点云语义分割和点云实例分割两个方面对点云语义理解研究进展进行了回顾。在此基础上,给出了三维视觉研究的未来发展趋势,旨在为相关研究者提供参考。     

Clever Support: Efficient Support Structure Generation for Digital Fabrication

We introduce an optimization framework for the reduction of support structures required by 3D printers based on Fused Deposition Modeling (FDM) technology. The printers need to connect overhangs with the lower parts of the object or the ground in order to print them. Since the support material needs to be printed first and discarded later, optimizing its volume can lead to material and printing time savings. We present a novel, geometry‐based approach that minimizes the support material while providing sufficient support. Using our approach, the input 3D model is first oriented into a position with minimal area that requires support. Then the points in this area that require support are detected. For these points the supporting structure is progressively built while attempting to minimize the overall length of the support structure. The resulting structure has a tree‐like shape that effectively supports the overhangs. We have tested our algorithm on the MakerBot® Replicator? 2 printer and we compared our solution to the embedded software solution in this printer and to Autodesk® Meshmixer? software. Our solution reduced printing time by an average of 29.4% (ranging from 13.9% to 49.5%) and the amount of material by 40.5% (ranging from 24.5% to 68.1%).     

Nozzle condition monitoring in 3D printing

3D printing and particularly fused filament fabrication is widely used for prototyping and fabricating low-cost customized parts. However, current fused filament fabrication 3D printers have limited nozzle condition monitoring techniques to minimize nozzle clogging errors. Nozzle clogging is one of the most significant process errors in current fused filament fabrication 3D printers, and it affects the quality of the prototyped parts in terms of geometry tolerance, surface roughness, and mechanical properties. This paper proposes a nozzle condition monitoring technique in fused filament fabrication 3D printing using a vibration sensor, which is briefly described as follows. First, a bar mount that supports the liquefier in fused filament fabrication extruder was modeled as a beam excited by a system of process forces. The boundary conditions were identified, and the applied forces were analyzed for Direct and Bowden types of fused filament fabrication extruders. Second, a new 3D printer with a fixed extruder and a moving platform was designed and built for conducting nozzle condition monitoring experiments. Third, nozzle clogging was simulated by reducing the nozzle extrusion temperature, which caused partial solidification of the filament around inner walls of the nozzle. Fourth, sets of experiments were performed by measuring the vibrations of a bar mount during extrusion of polylactic acid, acrylonitrile butadiene styrene, and SemiFlex filaments via Direct and Bowden types of fused filament fabrication extruders. Findings of the current study show that nozzle clogging in fused filament fabrication 3D printers can be monitored using an accelerometer sensor by measuring extruder’s bar mount vibrations. The proposed technique can be used efficiently for monitoring nozzle clogging in fused filament fabrication 3D printers as it is based on the fundamental process modeling.     

施工管理虚拟环境中的CAD识别和三维重构

给出了识别CAD系统设计结果的数据,并在此基础上介绍了进行三维建模的施工管理虚拟环境,提出了有效的基于OpenGL的三维重构解决方案.在该环境中指定各结构构件间、结构构件同其它数据的相关物理及逻辑属性,动态的模拟施工过程,可以实现施工优化控制和相应的资源可视化管理.     

PackMerger: A 3D Print Volume Optimizer

We propose an optimization framework for 3D printing that seeks to save printing time and the support material required to print 3D shapes. Three‐dimensional printing technology is rapidly maturing and may revolutionize how we manufacture objects. The total cost of printing, however, is governed by numerous factors which include not only the price of the printer but also the amount of material and time to fabricate the shape. Our PackMerger framework converts the input 3D watertight mesh into a shell by hollowing its inner parts. The shell is then divided into segments. The location of splits is controlled based on several parameters, including the size of the connection areas or volume of each segment. The pieces are then tightly packed using optimization. The optimization attempts to minimize the amount of support material and the bounding box volume of the packed segments while keeping the number of segments minimal. The final packed configuration can be printed with substantial time and material savings, while also allowing printing of objects that would not fit into the printer volume. We have tested our system on three different printers and it shows a reduction of 5–30% of the printing time while simultaneously saving 15–65% of the support material. The optimization time was approximately 1 min. Once the segments are printed, they need to be assembled.     

基于Android的云打印平台实现

随着云计算概念的提出及其技术日渐趋于成熟，云打印等相关新兴技术也随之兴起。本文首先介绍了云打印的概念和基本框架，然后分别从客户端和服务端搭建云打印平台，以满足从客户端上传需打印的文件、商家从服务端管理打印订单的要求，从技术层面上重新设计打印资源的整合与发布，解决传统网络打印的地域限制等问题。以Android手机为客户端的云打印平台系统，实现了用户随时随地在线打印，极大地满足了用户打印文件的需求。     

制造资源耦合映射与模糊匹配技术研究

针对云制造中云制造服务资源匹配映射多种模式并存,云制造服务资源与云制造资源需求间相互影响且映射关系复杂,导致缺少有效云制造服务资源匹配方法.在综合考虑云制造资源需求间相互影响的基础上,提出了云制造服务资源匹配模型,利用模糊积分度量用户云制造资源需求与云制造服务资源间的匹配程度,提出了基于模糊积分的云制造服务资源匹配方法.通过基于模糊积分的云制造服务资源匹配方法,计算获得云制造服务资源对云制造资源需求的匹配度,为制造云中的终端用户提供按需、自助、敏捷的云制造服务资源智能匹配技术.最后,以中小模具企业云制造平台某型号多工位级进模具排样图设计应用为实例,证明了文中方法在工程应用中的正确性与高效性.     

Clean color: Improving multi‐filament 3D prints

Fused Filament Fabrication is an additive manufacturing process by which a 3D object is created from plastic filament. The filament is pushed through a hot nozzle where it melts. The nozzle deposits plastic layer after layer to create the final object. This process has been popularized by the RepRap community. Several printers feature multiple extruders, allowing objects to be formed from multiple materials or colors. The extruders are mounted side by side on the printer carriage. However, the print quality suffers when objects with color patterns are printed – a disappointment for designers interested in 3D printing their colored digital models. The most severe issue is the oozing of plastic from the idle extruders: Plastics of different colors bleed onto each other giving the surface a smudged aspect, excess strings oozing from the extruder deposit on the surface, and holes appear due to this missing plastic. Fixing this issue is difficult: increasing the printing speed reduces oozing but also degrades surface quality – on large prints the required speed level become impractical. Adding a physical mechanism increases cost and print time as extruders travel to a cleaning station. Instead, we rely on software and exploit degrees of freedom of the printing process. We introduce three techniques that complement each other in improving the print quality significantly. We first reduce the impact of oozing plastic by choosing a better azimuth angle for the printed part. We build a disposable rampart in close proximity of the part, giving the extruders the opportunity to wipe oozing strings and refill with hot plastic. We finally introduce a toolpath planner avoiding and hiding most of the defects due to oozing, and seamlessly integrating the rampart. We demonstrate our technique on several challenging multiple color prints, and show that our tool path planner improves the surface finish of single color prints as well.     

基于嵌入式Linux的打印控制系统的设计

本文介绍了一种基于嵌入式Linux的打印控制系统，并给出了软、硬件的整体设计方案。这一方案应用先进的ARM嵌入式技术，使当前必须由计算机来驱动的打印机，完全脱离了计算机的束缚，形成一套完整独立的打印系统，能完成预览、编辑、控制、打印的功能。     

基于点云数据的复杂建筑体真三维建模与应用

传统建筑物三维建模方法费时费力、精度低、采用接触式测量,且仅能获得建筑物少量特征点及线状数据。与传统测量方法相比,地面三维激光扫描技术(Terrestrial Laser Scanner,TLS)方法可快速、高效、非接触式地获取建筑物表面高精度三维信息,因此其较传统建筑物三维建模方法优势显著。以古田会议旧址为研究对象,首先介绍了研究目标的主要特征以及点云数据采集方案;其次以高复杂度建筑物建模为需求出发,详细阐述了点云数据预处理及建筑物三维模型重建相关核心技术及方法;并重点讨论了与其相关的点云数据配准拼接、去噪简化、二维轮廓线提取、三维实体重建;最后实现古田会议旧址高复杂度三维几何模型重现,并采用先进的3D打印技术按1∶40比例尺制作3D打印点云数据的微缩模型。通过与实地测量数据对比分析得知,采用地面三维激光测量方法采集点云数据的建筑物建模精度优于传统测量方法。此研究成果可应用于古田会议旧址等文化遗产的文物修复、变形监测、虚拟重现等方面。     

3D reconstruction of human face based on an improved seeds-growing algorithm

An algorithm based on binocular stereo vision is proposed to generate 3D (three-dimensional) dense points cloud model of the human face. A two-step matching strategy from sparse to dense is developed. Firstly, an improved seeds-growing algorithm is utilized to acquire sparse matching of high confidence. Secondly, based on the control points method and piecewise dynamic programming, the dense matching is completed. Experimental results show that the proposed algorithm can produce smooth and dense 3D points cloud model of the human face.