A Constraint-Based Methodology For Product Design With Virtual Reality

The absence of constraints is one of the major limitations in current Virtual Reality (VR) environments. Without constraints, it is difficult to perform precise 3D interactive manipulations in VR environments and precise solid modelling in VR environments cannot be guaranteed. In this paper, constraints are incorporated into the VR environment for intuitive and precise solid modelling. A hierarchically structured constraint-based data model is developed to support solid modelling in the VR environment. Solid modelling in the VR environment is precisely performed in an intuitive manner through constraint-based manipulations. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction to establish the hierarchically structured constraint-based data model and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving allowable motions from constraints. A procedure-based degree-of-freedom incorporation approach for 3D constraint solving is presented for deriving the allowable motions. A rule-based constraint recognition engine is developed for both constraint-based manipulations and implicitly incorporating constraints into the VR environment. A prototype system has been implemented for precise solid modelling in an intuitive manner through constraint-based manipulations in the VR environment.

A methodology for solid modelling in a virtual reality environment

With today's virtual reality (VR) systems, it is difficult to create precise assembly models through 3D interactions due to hardware limitations. In this paper, an efficient approach is presented for intuitive and precise assembly modeling in a VR environment. Assembly modelling is performed by precise constraint-based 3D direct manipulations in an intuitive manner. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction, and are realized by allowable motions for precise 3D interactions in the VR environment. Some special constraint-based assembly operations are constructed for assembly modelling in the VR environment. A method for recognizing the pairs of mating features between assembly components is presented. This method integrates 3D direct manipulations with a feature mating knowledge base and makes the process of recognizing a pair of mating features intuitive. A concept of offset solid is also presented for determining assembly components. A prototype system has been developed for assembly modelling through precise constraint-based manipulations in an intuitive manner in the VR environment.

The absence of constraints when interacting with virtual objects is one of the major limitations in the current Virtual Reality (VR) environments. Without constraints, it is difficult to perform precise interactive manipulations and precise solid modelling in VR environments cannot be ensured. In this paper, constraint-based 3D direct manipulations are acquired through incorporating constraints into the VR environment for intuitive and precise solid modelling. Solid modelling in the VR environment is precisely performed in an intuitive manner through precise constraint-based manipulations. Constraint-based manipulations are accompanied by automatic constraint recognition and precise constraint satisfaction and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving the allowable motions from constraints. A procedure-based degree-of-freedom incorporation approach for 3D constraint solving is presented to derive the allowable motions. A rule-based constraint recognition engine is developed for both constraint-based manipulations and implicitly incorporating constraints into the VR environment. Some special constraint-based manipulations are also implemented as modelling operations for solid modelling in the VR environment.

With today’s virtual reality (VR) systems, it is difficult to directly and precisely create and modify objects in a VR environment. This chapter presents an approach for solid modelling in a VR environment. Solid modelling in the VR environment is performed precisely in an intuitive manner through constraint-based manipulations. A hierarchically structured and constraint-based data model is developed to support solid modelling in the VR environment. The data model integrates a high-level constraint-based model for precise object definition, a mid-level constructive solid geometry/boundary representation (CSG/BRep) hybrid solid model for hierarchical geometry abstractions and object creation, and a low-level polygon model for real-time visualization and interaction in the VR environment. Constraints are embedded in the solid model and are organized at different levels to reflect the modelling process from features to parts. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction to establish the hierarchically structured constraint-based data model and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving allowable motions from constraints. A procedure-based degree-of-freedom (DOF) combination approach for 3D constraint solving is presented for deriving the allowable motions.

Virtual Reality (VR) technology is a natural extension of 3D computer graphics with advanced input and output devices and brings a completely new environment to the CAD community. However, with today’s VR systems, it is difficult to directly and precisely create and modify objects in a VR environment. This paper presents an efficient approach for solid modelling in a VR environment. Solid modelling in the VR environment is precisely performed in an intuitive manner through precise constraint-based manipulations. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction for establishing the hierarchically structured constraint-based data model and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving the allowable motions from constraints. A procedure-based degree-of-freedom incorporation method for 3D constraint solving is presented for deriving the allowable motions. A rule-based constraint recognition engine is developed for automatic constraint recognition. A prototype system has been developed for solid modelling in the VR environment, where the user can create solid models in an intuitive manner through precise constraint-based manipulations.

This paper presents a constraint-based methodology for intuitive and precise solid modelling in a virtual reality (VR) environment. A hierarchically structured and constraint-based data model is developed to support solid modelling in the VR environment. A constraint reasoning engine is also developed to automatically deduce allowable motions for precise constraint-based 3D manipulations. A prototype system of product modelling has been successfully developed, and experimental results demonstrate the advantage of precise solid modelling through constraint-based manipulation in virtual environments.

The absence of efficient constraint management facilities when interacting with virtual objects is one of the major limitations of current virtual reality (VR) systems for CAD applications. Without constraint management facilities, it is difficult to perform precise interactions with today's 3D input devices and precise solid modeling in the VR environments cannot be ensured. In this paper, a constraint manager is presented for intuitive and precise solid modeling in the VR environment. This constraint manager generates constraint-based 3D direct manipulations for precise solid modeling through incorporating constraints into the VR environment. Constraint-based manipulations are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving allowable motions from constraints. A procedure-based degree-of-freedom incorporation solver for solving 3D constraints is presented for deriving the allowable motions. A rule-based constraint recognition engine is developed for implicitly incorporating constraints into the VR environment.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality environment

A hierarchically structured constraint-based data model for solid modelling in a virtual reality environment is presented. The data model integrates a high-level constraint-based model for precise object definition, a mid-level CSG/Brep hybrid solid model for supporting hierarchical geometry abstractions and object creation, and a low-level polygon model for real-time visualization and interaction in the virtual reality environment. Constraints are embedded in the solid model and organized at different levels to reflect the entire solid modelling process from features and parts, to assemblies. This model not only provides precise object definition, but also supports real-time visualization and interaction in the VR environment. Furthermore, it has the potential to obtain precise 3D interactions and precise constraint-based manipulations can be deduced from the data model to carry out precise solid modelling in the VR environment.

Virtual reality (VR) provides a completely digital world of interaction which enables the users to modify, edit, and transform digital elements in a responsive way. Mixed reality (MR), which is the result of blending the digital world and the physical world together, brings new advancements and challenges to human, computer and environment interactions. This paper focuses on adapting the already-existing methods and tools in architecture to both VR and MR environments under sustainable architectural design domain. For this purpose, we benefit from the semantically enriched data platforms of Building information modelling (BIM) tools, the performance calculation functions of building energy simulation tools while transcending these data into VR and MR environments. In this way, we were able to merge these diverse data for the virtual design activity. Nine participants have already tested the initial prototype of MR-based only interaction environment in our previous study [1]. According to the feedbacks, the user interface and interaction mechanisms were updated and the environment was made accessible also in VR. These updates made four types of interactions possible in MR and VR: 1) MR environment using HoloLens with gestures, 2) MR environment using HoloLens with a clicker, 3) VR environment using HTC Vive with two controllers, and 4) HoloLens emulator with a mouse. All these interaction cases were tested by 21 architecture students in an in-house workshop. In this workshop, we collected data on presence, usability, and technology acceptance of these cases. Our results show that interaction in a VR environment is the most natural interaction type and the participants were eager to use both MR and VR environments instead of an emulator. To our best of knowledge, this is the first comparative study of a BIM-based architectural design medium in both VR and MR environments.

With today's virtual reality systems, it is difficult to directly and precisely create and modify complex objects in a virtual reality environment. One of the most important reasons is the absence of a suitable model representation that can efficiently support solid modelling in a virtual reality environment. A hierarchically structured constraint-based data model for solid modelling in the virtual reality environment is presented in this paper. The data model integrates a high-level constraint-based model for precise object definition, a mid-level CSG/B rep hybrid solid model for supporting hierarchical geometry abstractions and object creation, and a low-level polygon model for real-time visualization and interaction in the virtual reality environment. Constraints are embedded in the solid model and are organized at different levels to reflect the process of solid modelling. This data model not only provides precise object definition, but also supports real-time visualization and interaction in the virtual reality environment.

This paper presents an intuitive approach to precise solid modelling in virtual reality environments. A hierarchically structured model is established to handle the tasks of object definition, object creation, and object rendering with an integrated data structure. Constraints are organized at different levels on different objects and are embedded in the data structure. A constraint reasoning engine is developed to automatically determine allowable motions for precise manipulation of virtual objects with online assistance from constraints. Examples are presented to demonstrate the advantage of precise solid modelling through constraint-based manipulations in virtual environments.

This paper presents an approach for intuitive and precise solid modeling in virtual reality environments. It develops a hierarchically structured and constraint-based data model to support object modeling, and uses automatic constraint recognition and precise constraint satisfaction to assist object manipulation. The proposed data model integrates a high-level constraint-based model, a mid-level hybrid solid model, and a low-level polygon model for object definition, object creation, and real-time interaction respectively. Constraint-based modeling operations and typical locating methods are also provided in the paper with details.

Constraint-Based Modeling (CBM) is an effective student modeling approach which has been used successfully in a wide range of instructional domains. Within the Intelligent Computer Tutoring Group (ICTG), we have developed numerous constraint-based tutors and demonstrated their effectiveness in real courses. In this paper, however, we discuss how we use CBM in the area of cognitive rehabilitation after stroke. Our computer-based treatment is aimed at improving prospective memory. Participants are first trained on how to use visual imagery and then practice in a Virtual Reality (VR) environment. We present how we use constraints to track the participant’s progress when performing tasks in the VR environment.