Assessing the impact of geometric design intent annotations on parametric model alteration activities

The effective representation and communication of design intent plays a crucial role in CAD model alteration activities. In history-based parametric modeling systems, design intent information is usually expressed implicitly within the model. However, there is evidence that suggests that an explicit representation can increase productivity and quality and facilitate the transferring of design knowledge throughout the different stages of the product lifecycle. In this paper, we assess the effectiveness of 3D annotations as mechanisms for explicit design intent representation and examine their impact in model alteration processes that require a direct interaction with the model's geometry. We present the results of a series of studies aimed at measuring user performance and model quality in two scenarios. First, we hypothesized that annotations are valuable tools to provide design information when inadequate modeling assumptions can be made by designers. Second, we evaluated annotations as tools to communicate design decisions when multiple options are available. In both cases, results show statistically significant benefits of annotated models, suggesting the use of this technique as a valuable approach to improve design intent communication.     

Product information visualization and augmentation in collaborative design

In this paper, a collaborative system for product information visualization and augmentation is presented. The developed system allows the users, who can be remotely distributed, to view a product model, which is a geometric representation of the product, from different perspectives. They can choose to view design and product history, such as previous modification processes and feature information of the product independently. The product models displayed to the users are immediately updated after any design modifications have been made to the CAD model. Product features being discussed can be highlighted to draw the users’ attention. In addition, modifications can be displayed dynamically for the users to evaluate the design effect. The product history document module in the system provides a user-friendly interface for retrieving design records. After a specific record has been chosen, the related product model is displayed, and it can be aligned with the current product model for the ease of comparison and evaluation. The feature information of the product is displayed using virtual “floating” annotations linked to the related features. A user interface to enter annotations is provided, and the annotations entered by different users can be shared in real time. A cluster-based greedy algorithm is implemented to avoid overlapping annotations in the field of view.     

A procedural method to exchange editable 3D data from a free-hand 2D sketch modeling system into 3D mechanical CAD systems

In the concept development phase, a designer wants to rapidly create a product’s overall shape and user interfaces by making simple sketches, known as ‘thumbnail sketches’, to evaluate ideas and possibilities. Free-hand 2D sketch systems are regarded as a computerized tool for making thumbnail sketches. After the concept development phase, subsequent editing of the 3D data reconstructed from a free-hand 2D sketch with a 3D mechanical CAD system in the detail design phase is indispensable because inaccurate dimensions are inherent in a free-hand 2D sketch. For this reason, we present a new method to translate 3D data reconstructed from a free-hand 2D sketch into an editable form that reflects design intent so that the translated data can be directly used in 3D mechanical CAD systems. The feasibility of the proposed method has been demonstrated through experiments with prototype systems.     

Similarity assessment of 3D mechanical components for design reuse

Duplicate designs consume a significant amount of resources in most new product development. Search of similar parts for a given query part is the key to avoid this problem by facilitating design reuse. Most search algorithms convert the CAD model into a shape signature and compute the similarity between two models according to a measure function of their signatures. However, each algorithm defines the shape signature in a different way, and thus has its own limitations in discriminating 3D parts. This paper proposes a search scheme that successfully complements various shape signatures in similarity assessment of 3D mechanical components. It considers form-feature, topological, and geometric information in component comparison. Such an integrated approach can effectively solve the feature intersection problem, inherited in any feature-based approaches, and capture the user's intent more precisely in the search, which geometry-based methods fail to accomplish. We also develop a set of algorithms that performs the component comparison in a polynomial time. The proposed scheme is implemented in a product design environment consisting of commercial CAD and PDM systems. The result demonstrates the practicality of this work in automatic search of similar mechanical components for design reuse.     

Conformance checking of PMI representation in CAD model STEP data exchange files

Recommended practices supplement data exchange standards by providing common implementation guidance associated with specific requirements. ISO 10303 (STEP) product data exchange files that conform to recommended practices ensure interoperability between computer-aided design (CAD) systems and with downstream applications such as manufacturing and inspection. Correct implementation of product and manufacturing information (PMI)–annotations associated with a CAD model’s edges and faces such as geometric tolerances, dimensional tolerances, and datum features–in CAD authoring systems and translators is essential for interoperability. This paper discusses an approach implemented in a software tool for checking the conformance of STEP files to the recommended practice for PMI representation.     

Detecting design intent in approximate CAD models using symmetry

Finding design intent embodied as high-level geometric relations between a CAD model’s sub-parts facilitates various tasks such as model editing and analysis. This is especially important for boundary-representation models arising from, e.g., reverse engineering or CAD data transfer. These lack explicit information about design intent, and often the intended geometric relations are only approximately present. A novel solution to this problem is presented based on detecting approximate local incomplete symmetries, in a hierarchical decomposition of the model into simpler, more symmetric sub-parts. Design intent is detected as congruencies, symmetries and symmetric arrangements of the leaf-parts in this decomposition. All elementary 3D symmetry types and common symmetric arrangements are considered. They may be present only locally in subsets of the leaf-parts, and may also be incomplete, i.e. not all elements required for a symmetry need be present. Adaptive tolerance intervals are detected automatically for matching inter-point distances, enabling efficient, robust and consistent detection of approximate symmetries. Doing so avoids finding many spurious relations, reliably resolves ambiguities between relations, and reduces inconsistencies. Experiments show that detected relations reveal significant design intent.     

SmartAnnotator An Interactive Tool for Annotating Indoor RGBD Images

RGBD images with high quality annotations, both in the form of geometric (i.e., segmentation) and structural (i.e., how do the segments mutually relate in 3D) information, provide valuable priors for a diverse range of applications in scene understanding and image manipulation. While it is now simple to acquire RGBD images, annotating them, automatically or manually, remains challenging. We present Smart Annotator , an interactive system to facilitate annotating raw RGBD images. The system performs the tedious tasks of grouping pixels, creating potential abstracted cuboids, inferring object interactions in 3D, and generates an ordered list of hypotheses. The user simply has to flip through the suggestions for segment labels, finalize a selection, and the system updates the remaining hypotheses. As annotations are finalized, the process becomes simpler with fewer ambiguities to resolve. Moreover, as more scenes are annotated, the system makes better suggestions based on the structural and geometric priors learned from previous annotation sessions. We test the system on a large number of indoor scenes across different users and experimental settings, validate the results on existing benchmark datasets, and report significant improvements over low‐level annotation alternatives. (Code and benchmark datasets are publicly available on the project page.)     

基于UG的采煤机防爆盖板三维标注及数控工艺研究

随着三维CAD技术的发展,产品制造信息在三维模型和二维图纸之间的反复传递,严重影响了产品制造信息的正确、快速传递。基于三维产品制造信息技术,以采煤机防爆盖板为例,在UG NX10.0中建立了防爆盖板的三维模型并进行了三维标注,设计了加工工艺路线,规划了数控加工刀具轨迹,进行了加工仿真,验证了数控加工的正确性,在此基础上完成了采煤机防爆盖板的三维工艺式设计。该研究对基于模型定义的数字化设计与制造研究,实现制造业信息化具有重要意义。     

Exploring Social Annotations with the Application to Web Page Recommendation

Collaborative social annotation systems allow users to record and share their original keywords or tag attachments to Web resources such as Web pages, photos, or videos. These annotations are a method for organizing and labeling information. They have the potential to help users navigate the Web and locate the needed resources. However, since annotations are posted by users under no central control, there exist problems such as spam and synonymous annotations. To efficiently use annotation information to facilitate knowledge discovery from the Web, it is advantageous if we organize social annotations from semantic perspective and embed them into algorithms for knowledge discovery. This inspires the Web page recommendation with annotations, in which users and Web pages are clustered so that semantically similar items can be related. In this paper we propose four graphic models which cluster users, Web pages and annotations and recommend Web pages for given users by assigning items to the right cluster first. The algorithms are then compared to the classical collaborative filtering recommendation method on a real-world data set. Our result indicates that the graphic models provide better recommendation performance and are robust to fit for the real applications.     

From paper-and-pen annotations to artefact-based mobile learning

Making annotations on books and learning materials is part of students' everyday life. Although there are many computer-based annotation systems, many people prefer to print digital documents and make annotations on physical paper. We introduce a classification scheme for computer-based annotation systems and provide an overview of different systems using this scheme. During our investigations, we identified several shortcomings in existing annotation systems: limitation to single document formats, no capturing of relations to reflect lateral reading, loss of context information an annotation was created in and limited sharing capabilities among collaborative users. To overcome these shortcomings, we introduce the concepts of Anchor Points , Artefacts and Spaces . Anchor Points define locations in arbitrary documents. Artefacts capture annotations on multiple Anchor Points in several documents, allowing students to map their current working context that typically contains several open documents and a relationship between them. Spaces are repositories for the learning materials and annotations that are automatically replicated among collaborative mobile users.     

THE OBJECT-ORIENTED INTELLIGENT PROGRAMMING IN CAD/CAM

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A new approach to automatic and a priori mesh adaptation around circular holes for finite element analysis

Through our research on the integration of finite element analysis in the design and manufacturing process with CAD, we have proposed the concept of mesh pre-optimization. This concept consists in converting shape and analysis information in a size map (a mesh sizing function) with respect to various adaptation criteria (refining the mesh around geometric form features, minimizing the geometric discretization error, boundary conditions, etc.). This size map then represents a constraint that has to be respected by automatic mesh generation procedures. This paper introduces a new approach to automatic mesh adaptation around circular holes. This tool aims at optimizing, before any FEA, the mesh of a CAD model around circular holes. This approach, referred to as “a priori” mesh adaptation, should not be regarded as an alternative to adaptive a posteriori mesh refinement but as an efficient way to obtain reasonably accurate FEA results before a posteriori adaptation, which is particularly interesting when evaluating design scenarios. The approach is based on performing many offline FEA analyses on a reference case and deriving, from results and error distributions obtained, a relationship between mesh size and FEA error. This relationship can then be extended to target user specified FEA accuracy objectives in a priori mesh adaptation for any distribution of circular holes. The approach being purely heuristic, fulfilling FEA accuracy objectives, in all cases, cannot be theoretically guaranteed. However, results obtained using varying hole diameters and distributions in 2D show that this heuristic approach is reliable and useful. Preliminary results also show that extension of the method can be foreseen towards a priori mesh adaptation in 3D and mesh adaptation around other types of 2D features.     

Effective Annotations Over 3D Models

Annotation support in interactive systems is often considered a simple task by the CG community, since it entails the apparently easy selection of a region and its connection with some information. The reality appears more complex. The scope of this paper is two-fold: first, to review the status of this domain, discussing and characterizing several approaches proposed in literature to manage annotations over geometric models; second, to present in detail an innovative solution proposed and assessed in the framework of Cultural Heritage (CH) applications, called ClippingVolumes. At the annotation definition stage ClippingVolumes uses 3D data to characterize the annotation region; subsequently, annotations are visualized by adopting a two-pass rendering solution which uses stencil buffers, thus without introducing new geometric elements, changing the topology or duplicating geometry elements. It solves most of the issues that afflict the current state of the art, such as fragmentation, annotation transfer to multiple representations and multi-resolution data encoding. The latter is a mandatory requirement to produce efficient web-based systems. We implemented and we fully tested this approach in the framework of a complex system that supports the documentation of CH restoration projects.     

The LEMO annotation framework: weaving multimedia annotations with the web

Cultural institutions and museums have realized that annotations contribute valuable metadata for search and retrieval, which in turn can increase the visibility of the digital items they expose via their digital library systems. By exploiting annotations created by others, visitors can discover content they would not have found otherwise, which implies that annotations must be accessible and processable for humans and machines. Currently, however, there exists no widely adopted annotation standard that goes beyond specific media types. Most institutions build their own in-house annotation solution and employ proprietary annotation models, which are not interoperable with those of other systems. As a result, annotation data are usually stored in closed data silos and visible and processable only within the scope of a certain annotation system. As the main contribution of this paper, we present the LEMO Annotation Framework. It (1) provides a uniform annotation model for multimedia contents and various types of annotations, (2) can address fragments of various content-types in a uniform, interoperable manner and (3) pulls annotations out of closed data silos and makes them available as interoperable, dereferencable Web resources. With the LEMO Annotation Framework annotations become part of the Web and can be processed, linked, and referenced by other services. This in turn leads to even higher visibility and increases the potential value of annotations.     

IMAF: in situ indoor modeling and annotation framework on mobile phones

The widespread use of smart phones with GPS and orientation sensors opens up new possibilities for location-based annotations in outdoor environments. However, a completely different approach is required for indoors. In this study, we introduce IMAF, a novel indoor modeling and annotation framework on a mobile phone. The framework produces a 3D room model in situ with five selections from user without prior knowledge on actual geometry distance or additional apparatus. Using the framework, non-experts can easily capture room dimensions and annotate locations and objects within the room for linking virtual information to the real space represented by an approximated box. For registering 3D room model to the real space, an hybrid method of visual tracking and device sensors obtains accurate orientation tracking result and still achieves interactive frame-rates for real-time applications on a mobile phone. Once the created room model is registered to the real space, user-generated annotations can be attached and viewed in AR and VR modes. Finally, the framework supports object-based space to space registration for viewing and creating annotations from different views other than the view that generated the annotations. The performance of the proposed framework is demonstrated with achieved model accuracy, modeling time, stability of visual tracking and satisfaction of annotation. In the last section, we present two exemplar applications built on IMAF.     

基于虚拟原型的概念设计描述模型V-desModel

传统的概念设计方法由于缺乏真实感的交互手段,难以直观表达设计者的意图.基于虚拟原型的概念设计不仅能为设计者提供逼真的虚拟设计环境,而且充分体现了现代设计的成本低、周期短以及灵活性强等特点.针对概念设计的特点以及虚拟原型的特征分类,提出了基于虚拟原型的概念设计模型V-desModel,其核心是利用产品视图模型描述设计对象,将虚拟特征概念融入视图模型中,并采用可扩展"三维实体-约束图"来描述设计对象之间的约束关系.V-desModel模型能有效地支持基于虚拟原型的概念设计过程,较好地解决了概念设计中产品虚拟原     

用三维几何约束构建概念化设计阶段的三维布局

概念化设计是产品设计中的一个重要环节，其主要任务是实施产品结构的空间布局，并确定连接关系．由于概念化设计阶段产品结构信息不明确，因此现有的三维设计工具(如solidedge7．0，MDT等)无法有效支持概念化阶段的设计活动．在对装配关系进行抽象的基础上，利用三维约束与驱动实现概念化设计阶段的空间布局设计活动，为进行三维设计工具自顶向下的设计模式奠定了基础．     

超二维环境下尺寸驱动和参数设计的研究

超二维环境的最大特点在于使用了二维数据表示三维模型，实现了不建立三维模型直接对三维模型的各向投影进行参数设计，直接修改复杂工程图，由于相对三维工程实体，纯二维数据信息量不足，而按以往方法用多视图来弥补，又因视图间缺乏必要联系，无法建立和描述三维信息，因而，超二维模型引入视图投影信息，使之具有一定的三维信息。通过结合当前尺寸驱动和参数设计的现状，在超二维环境下，引和高等画法几何学多视图间的投影原理，     

基于三维实体模型的钢结构工业厂房CAD/CAM软件后处理系统

为提高钢结构工业厂房设计的准确性、精确度和工作效率,为某钢结构工业厂房CAD/CAM软件研制出基于三维实体模型的后处理系统.该系统基于面向对象的编程技术,抽象出描述实际结构零件几何信息、结构特征和设计条件的智能型实体对象.将对象以及对象之间的层次关系和逻辑关系存储在AutoCAD图形数据库中,形成三维实体模型,用于直观、准确和完整地表现具有复杂空间关系和细部构造的真实结构;实现数据库对象的建立、编辑、查询、显示和数据整理等操作.该系统结合具体结构形式的特点,实现用于施工图设计和深化设计的全部关键功能.