Approach to Modeling and Virtual-reality-based Simulation for Plant Canopy Lighting

Over the past 20 years, significant progress has been made in virtual plant modeling corresponding to the rapid advances in information technology. Virtual plant research has broad applications in agronomy, forestry, ecol- ogy and remote sensing. As many biological processes are driven by light, it is the key for virtual plant to estimate the light absorbed by each organ. This paper presents the radiance equation suitable for calculating sun and sky light intercepted by plant organs based on the principles of the interaction between light and plant canopy firstly; analyzes the process principles of plant canopy primary lighting based on ray casting and projection secondly; describes the multiple scattering of plant lighting based on Monte Carlo ray tracing method and on the radiosity method thirdly; and confirms the research with 3D visualization based on Virtual Reality Modeling Language (VRML) finally. The research is the primary work of digital agriculture, and important for monitoring and estimating corn growth in Northeast China.

Virtual Reality with Haptic Application

Virtual reality (VR) is the use of advanced technologies, including computers and various multimedia peripherals (such as haptic), to produce a simulated environment that users perceive as comparable to real world objects and events. With the aid of specially designed transducers and sensors, users interact with displayed images, moving and manipulating virtual objects, and performing other actions in a way that engenders a feeling of actual presence (immersion) in the simulated environment. Haptic interfaces provide carefully controlled force feedback to the fingers of the user so that they feel as though they are touching objects in the virtual landscape. This article presented an overview to the concepts of VR focusing on haptics in a variety of interfaces and applications.

WEB-BASED VIRTUAL CNC MACHINE MODELING AND OPERATION

A CNC simulation system based on intemet for operation training of manufacturing facility and manufacturing process simulation is proposed. Firstly, the system framework and a rapid modeling method of CNC machine tool are studied under the virtual environment based on PolyTrans and CAD software. Then, a new method is proposed to enhance and expand the interactive ability of virtual reality modeling language（VRML） by attaining communication among VRML, JavaApplet, JavaScript and Html so as to realize the virtual operation for CNC machine tool. Moreover, the algorithm of material removed simulation based on VRML Z-map is presented. The advantages of this algorithm include less memory requirement and much higher computation. Lastly, the CNC milling machine is taken as an illustrative example for the prototype development in order to validate the feasibility of the proposed approach.

Science Letters:Dynamic concision for three-dimensional reconstruction of human organ built with virtual reality modelling language (VRML)

This research studies the process of 3D reconstruction and dynamic concision based on 2D medical digital images using virtual reality modelling language (VRML) and JavaScript language, with a focus on how to realize the dynamic concision of 3D medical model with script node and sensor node in VRML. The 3D reconstruction and concision of body internal organs can be built with such high quality that they are better than those obtained from the traditional methods. With the function of dynamic concision, the VRML browser can offer better windows for man-computer interaction in real-time environment than ever before. 3D reconstruction and dynamic concision with VRML can be used to meet the requirement for the medical observation of 3D reconstruction and have a promising prospect in the fields of medical imaging.

Virtual Painting Environment Design on the Intemet Based on VRML Scene

How to build a commercial decorative paintings sale web with the function of see placing effect was explained before you buy. Especially, the user could remotely choose a painting and virtually place it on a model room, or even his own real room picture. ASP（Active Server Pages） was used to connect VRML and the database, and JavaScript was used to make3D interaction. In addition, the layered images and transparent images were proposed to solve the occlusion between background picture and foreground picture.

Web-Based Interactive Simulation of Weft Knitted Fabric

In order to realize parametric simulation of three-dimensional(3D)fabric structure based on web,a 3D model describing a plain knitted fabric,in which the cross-section of the yarn is circular shape and the path of the yarn is cubic B-spline curve,is proposed in this paper.With this model,the 3D simulation of the loop and of the basic structures of the knitted fabric is realized by using Virtual Reality Modeling Language(VRML).The virtual simulation scene is suitable for network transmission with freely available VRML browsers and can be translated,scaled and rotated quite arbitrarily.By using Java and External Authoring Interface(EAI)technology,the web-based interactive simulation platform of weft knitted fabric is established.The user can input type of structures,basic fabric parameters,and yarn colors interactively to obtain a more realistic simulation result in real-time.A new approach is provided to imitate the knitted fabric 3D appearance on network.