基于图像辅助的三维模型形状检索

随着3D建模技术的快速发展,互联网上可用的3D模型库出现了爆炸式增长,越来越多的3D模型可以方便地通过网络下载使用.这直接促使了3D形状检索技术的发展,即给出特定的搜索信息,要求系统搜索出符合要求的、相似的3D模型.文章提出了一种新的3D形状检索方法,以3D模型作为输入,系统将会从模型数据库中自动检索出与输入形状最相似的模型.对于给定的输入模型以及数据库中的每一个模型,首先由计算机生成多幅在不同视角下的2D草图;然后,应用Gabor滤波器对每一幅2D草图提取图像上的局部特征,并对特征进行量化,从而得到代表该图像特征的直方图,这样对于每一个3D模型将得到多个代表该模型的直方图;最终,通过对比两个模型之间直方图的相似性,可以得到它们的相似性值,从而检索出与输入模型最相似的模型.文章所提出的方法通过采取2D图像分析方法提取能反映3D模型的特征并计算出模型之间的相似性值.经过测试,在一些公开的数据集上得到了较好的效果.     

A mathematical model for transient analysis of computer systems

The study of computer system dynamic behavior is a prerequisite for the design and implementation of automatic mechanisms for performance control. An analytic technique for modelling the transient behavior of computer systems is presented and a suitable method for modelling job dynamics is given.

The system model is discussed from the viewpoint of transient analysis with particular reference to bottleneck identification and to bottleneck migration analysis.

A mathematical study is given together with a numerical algorithm. The model is validated on the basis of suitable experimental results.     

Product design logic for an intelligent product modelling system

Recent research in CAD systems has been conducted to realize intelligent processing. Several CAD systems and product modelling systems have been developed using AI techniques. However, in order to develop more intelligent CAD systems, the design logic which connects the functional requirement to the geometric and the technological information of the designed product must be evaluated.

A product model used in such intelligent CAD systems has to include not only the geometric and the technological information of the product but also the designer's thought process which explains the design logic.

Design logic is generally divided into two parts. One is the generalized design logic which is commonly used in the conceptual design of mechanical products. The other is the product specified design logic which is used in the fundamental and detailed design phase. Different logic is applied to each product. This type of design logic is often used in modification design and compilation design, where the dimensions of parts have to be modified according to different functional requirements. When the dimensions and accuracies of the products are defined in connection with the functional requirements through design logic, the CAD system can automatically make decisions according to the given requirements. In this paper, suitable presentation formats and processing functions for these two types of design logic are discussed.

The importance of design logic in product modelling is proven through several case studies in this paper. As a conclusion, the intelligent product modelling system is developed, which should expedite the progress of design automation in the near future. In conceptual design, the design logic is processed in the modelling system and the product structure, with the technological information decided automatically from the functional requirement. Automation in the detailed design phase is also facilitated by the modelling system using the product specified design logic in the product model.     

Modeling of AGV networks in flexible manufacturing systems

It is shown that Petri nets are useful tool for modeling of AGV networks in flexible manufacturing systems. In this paper we concentrate on a part of AGV (automated guided vheicle) system that behaves as concurrently and asynchronizingly in FSM.

The main idea of this paper is based on combining of some fundamental parts modeled by colored Petri nets, which are called simply “parts”.

It is also shown that our computer system enables that using the concept of parts, we can construct any AGV model without much effort by operating a mouse, and provides a simulation result.     

A facsimile-based graphics editing system by auxiliary mark recognition

This paper describes a facsimile-based graphics editing system using handwritten mark recognition, and presents some experimental results with the system. In a manner different from usual graphics editors based on CRT displays and data tablets, only facsimiles are used as input and output devices in this system. As the first stage in processing, a graphic subject is first given as a set of line drawings and characters handwritten on a sheet of paper, and it is then input into the computer as a binary picture from a facsimile transmitter. Auxiliary editing information is input into the computer as handwritten marks or seal marks prepared on a separate sheet of paper. As the second stage, the marks are recognized and used to create a mark parameter list for the graphics editing. Third, referencing the mark parameter list, the graphics are expressed by using a set of graphic commands, and edited by the computer. Finally, a correct edited copy of the graphics is constructed by picture processing based on graphic commands, and it is output to a facsimile receiver. Very good results have been obtained for various kinds of hand-written graphics by using the system described here.     

基于样本学习的人像线条画生成系统

介绍了一个基于样本学习的人脸线条画生成系统.该系统可以根据用户给定的正面人脸照片自动生成相应的人脸线条画.在系统中有两个关键技术,即非参数化采样方法和灵活的线条画模板.对于给定图像上的任意像素点及其邻域,通过在样本空间搜索并匹配所有的相似邻域,计算该像素点在相应的线条画上出现的条件概率;然后根据艺术家的风格和得到的条件概率绘制"期望的线条画";最后使用模板匹配得到最后的线条画.此方法可以生成高质量的正面人脸线条画.     

Sketch‐to‐Design: Context‐Based Part Assembly

Designing 3D objects from scratch is difficult, especially when the user intent is fuzzy and lacks a clear target form. We facilitate design by providing reference and inspiration from existing model contexts. We rethink model design as navigating through different possible combinations of part assemblies based on a large collection of pre‐segmented 3D models. We propose an interactive sketch‐to‐design system, where the user sketches prominent features of parts to combine. The sketched strokes are analysed individually, and more importantly, in context with the other parts to generate relevant shape suggestions via adesign galleryinterface. As a modelling session progresses and more parts get selected, contextual cues become increasingly dominant, and the model quickly converges to a final form. As a key enabler, we use pre‐learned part‐based contextual information to allow the user to quickly explore different combinations of parts. Our experiments demonstrate the effectiveness of our approach for efficiently designing new variations from existing shape collections.     

草绘3维人体建模的模板形变方法

目的 采用草绘交互方式直接构造3维人体模型是当前人体建模研究的重要课题之一.提出一种草绘3维人体建模的模板形变方法.方法 针对输入的草图,首先,采用关节点定位方法获取草图中的人体关节点,根据人体结构学约束识别人体骨架结构,通过解析人体轮廓草图获取人体草图特征;其次,通过骨架模板和外观轮廓模板形变,将草图特征映射到3维人体模型,实现3维人体建模.结果 草图解析方法能有效提取草图特征,通过模板形变方法生成3维人体模型,并在模型上保持草图特征;能适应不同用户的绘制习惯,且生成的3维人体模型可用于人体动画设计.结论 提出一种草绘3维人体建模的模板形变方法,支持用户采用草绘方式进行3维人体模型设计,方法具有良好的用户适应性,对3维动画创作具有重要意义.     

面向智能CAD的分层构造自动型方法

本文着重对由抽象符号转化成具体形体的技术作了研究，提出了分层构造的自动造型方法．它支持直接由抽象的设计方案自动生成设计结果的三维表示，因而更适合于以辅助方案设计为核心的智能ＣＡＤ系统．一个基于该自动造型方法的椅子智能ＣＡＤ实验系统已在浙江大学人工智能研究所投入运行．     

SketchSoup: Exploratory Ideation Using Design Sketches

A hallmark of early stage design is a number of quick‐and‐dirty sketches capturing design inspirations, model variations and alternate viewpoints of a visual concept. We present SketchSoup, a workflow that allows designers to explore the design space induced by such sketches. We take an unstructured collection of drawings as input, along with a small number of user‐provided correspondences as input. We register them using a multi‐image matching algorithm, and present them as a 2D interpolation space. By morphing sketches in this space, our approach produces plausible visualizations of shape and viewpoint variations despite the presence of sketch distortions that would prevent standard camera calibration and 3D reconstruction. In addition, our interpolated sketches can serve as inspiration for further drawings, which feed back into the design space as additional image inputs. SketchSoup thus fills a significant gap in the early ideation stage of conceptual design by allowing designers to make better informed choices before proceeding to more expensive 3D modelling and prototyping. From a technical standpoint, we describe an end‐to‐end system that judiciously combines and adapts various image processing techniques to the drawing domain—where the images are dominated not by colour, shading and texture, but by sketchy stroke contours.     

Online Personalised Non‐photorealistic Rendering Technique for 3D Geometry from Incremental Sketching

This paper presents an online personalised non‐photorealistic rendering (NPR) technique for 3D models generated from interactively sketched input. This technique has been integrated into a sketch‐based modelling system. It lets users interact with computers by drawing naturally, without specifying the number, order, or direction of strokes. After sketches are interpreted as 3D objects, they can be rendered with personalised drawing styles so that the reconstructed 3D model can be presented in a sketchy style similar in appearance to what have been drawn for the 3D model. This technique captures the user's drawing style without using template or prior knowledge of the sketching style. The personalised rendering style can be applied to both visible and initially invisible geometry. The rendering strokes are intelligently selected from the input sketches and mapped to edges of the 3D object. In addition, non‐geometric information such as surface textures can be added to the recognised object in different sketching modes. This will integrate sketch‐based incremental 3D modelling and NPR into conceptual design.     

A variational approach to a problem in boiler control

The paper describes work done in examining a particular problem of boiler control. The overall approach is the consideration of the boiler as a unit in the frequency control of an electrical power system.

The possibilities of including frequency control within the economic scheduling program are limited by the ability of the individual set to follow large amplitude load demands fast. This limitation is real and has arisen due to the previous empirical methods of control system design for this system. The scope of the problem outlined demands a broad approach.

One section describes the derivation of a large analytic non-linear computer model of a natural circulation, non-reheat, boiler. Conclusions are drawn as to the relative importance of various factors, design parameters and existing controls, to the dynamic characteristics of this system.

From these results, an even simpler model structure can be derived. A deterministic criterion, reflecting, for a single set, the regulating requirement of the system is desired and the resulting variational problem in two controls and two state variables is solved.

Similarly a one control problem is solved and by programming the open loop “optimal” control strategy, as input to the large analytic computer model, the effects of model simplification are demonstrated.     

一种基于手绘草图的三维建模方法研究

研究一种基于手绘草图进行三维建模的方法。将用户界面分为手势区、轮廓区、控制区、信息提示区等。根据手势区输入的手势以及控制区输入的控制信息,对轮廓区输入的二维信息构建三维模型。采用模板匹配的方法识别用户手势,采用容差环的方法识别用户输入的物体轮廓,根据生成的三维数据之间的分层信息构建物体表面三角网格,对物体进行三维建模。     

Inferring mirror symmetric 3D shapes from sketches

We describe a system for taking a 2D sketch of a mirror-symmetric 3D shape and lifting the curves to 3D, inferring the symmetry relationship from the original hand-drawn curves. The system takes as input a hand-drawn sketch and generates a set of 3D curves such that their orthogonal projection matches the input sketch. The main contribution is a method which is able to identify the symmetry relationship among the hand-drawn curves even in the presence of ambiguity in the sketch.     

整合概念设计与详细设计过程的笔式CAD系统研究

目前存在的CAD系统由于交互方式不自然,交互效率低,缺乏对概念设计中模糊信息的支持,中断了设计信息流,导致概念设计与后续设计过程断裂,增加了设计周期和工作量。针对当前CAD系统的不足,提出对于支持概念设计的笔式CAD系统的研究,并探讨实现这样一个系统的问题及解决。其目的在于通过高效地使用当前的手势识别和草图识别技术,支持用户从开始的模糊意图所产生的随手笔画,到最后进行精确定位和绘制,使概念设计与详细设计过程整合,减少工作量和缩短设计周期。     

多信息融合的深度学习人脸表情识别算法研究

人脸表情识别作为人机交互系统的重要组成部分,在安防监控、人机交互等领域有广泛的应用,是计算机视觉的研究热点。传统的卷积神经网络方法一般提取单张人脸图像或者人脸标记点作为特征提取的输入数据,未能考虑到人脸全域的表情信息。提出了一种基于三通道多信息融合的深度学习人脸表情识别模型,以人脸图像表情平静到高峰时期标记点坐标的相对位移为输入,提取整个人脸表情图像特征信息,模型融合了稀疏自编码器以提高对边缘特征提取效率。该模型在CK+数据集上进行了训练和测试,实验结果表明,与该领域中的同类算法相比,该算法模型提高了表情识别的准确率。     

三维手绘CAD系统的设计与表达

描述了一个基于手绘草图的三维设计系统,并给出了该系统的体系结构．该系统采用以草绘手势规则和草图语义自动机为基础的设计与表达的思路,描述了草图语义的获取、表达和理解方法,从而较好地支持了早期的三维产品概念设计．该系统以手写笔和手写板为交互输入设备,能够自然、高效地进行一些复杂的三维实体和三维场景设计．