A. M. Day

Recent Developments and Applications of Haptic Devices

Over recent years a variety of haptic feedback devices have been developed and are being used in a number of important applications. They range from joysticks used in the entertainment industry to specialised devices used in medical applications. This paper will describe the recent developments of these devices and show how they have been applied. It also examines how haptic feedback has been combined with visual display devices, such as virtual reality walls and workbenches, in order to improve the immersive experience.

A Survey of Haptic Rendering Techniques

Computer Graphics technologies have developed considerably over the past decades. Realistic virtual environments can be produced incorporating complex geometry for graphical objects and utilising hardware acceleration for per pixel effects. To enhance these environments, in terms of the immersive experience perceived by users, the humans sense of touch, or haptic system, can be exploited. To this end haptic feedback devices capable of exerting forces on the user are incorporated. The process of determining a reaction force for a given position of the haptic device is known as haptic rendering. For over a decade users have been able to interact with a virtual environment with a haptic device. This paper focuses on the haptic rendering algorithms which have been developed to compute forces as users manipulate the haptic device in the virtual environment.

Automatically generating large urban environments based on the footprint data of buildings

This paper focuses on the generation of three dimensional models of large urban/suburban environments. Previous work on the reconstruction of particular environments is based on multiple overlapping aerial or street level images. Unfortunately these approaches do not extend well to large environments. The main reasons for this are that they require expensive high-resolution aerial images and a labour intensive modelling or data capture procedure. Consequently methods have been developed to generate large urban environments based on environmental data such as elevation data or building footprints. This permits the model to be based on actual data for the area being modelled and at a cost far less than that of aerial images. By reducing the data given to the model generation procedure various parameters are undetermined. These include roof style and textured appearance. This paper focuses on the use of building footprint information to construct a three dimensional model. It uses LIDAR data to give the buildings a height value and assigns them a roof using new techniques for roof modelling.

Rendering of large and complex urban environments for real time heritage reconstructions

In this paper we describe a rendering package, which brings together a number of rendering techniques and optimisations to render large and complex urban environments at interactive frame rates. The package has been built on top of a proprietary Scene Graph structure developed for the CHARISMATIC project. The paper presents an integrated approach combining Real-time Optionally Adapting Meshes, View Frustum Culling, Occluder Shadows, Level of Detail for Houses and Motion Captured Avatars in a single application.We discuss the performance issues associated with our approaches and give comprehensive implementation details. We also consider implications of the trends in high performance graphics sub-systems for PCs in the context of data types and animations required for populated interactive virtual heritage experiences. Finally we present empirical results to demonstrate the importance of employing such techniques and the implications for practical virtual heritage applications.

Rapid procedural-modelling of architectural structures

This paper describes a range of procedural techniques being developed to allow historic building styles to be modelled in a rapid manner, suitable for extremely fast rendering. We are expecting these tools to be used to model large-scale urban virtual-environments, from ancient Rome to modern day Hong Kong.When creating large scenes, there are two particular problems that we need to address and overcome. Firstly, the need to model scenes efficiently leads to a sense of repetition of the models as a small number of individual models is used repeatedly. We believe that it is now feasible to avoid the sense of repetition by using models drawn from a large library of prototypes according to some well-defined tools. By using procedural modelling we hope to speed up the model-building process while providing a number of other benefits.The other problem with large scenes comes with rendering them at an acceptable frame rate. By incorporating our modellers with the scenegraph being used to render them, a series of techniques and attributes may be applied to the models to cull out geometry not visible to the viewer, and to provide smoother transitions between varying levels of detail, avoiding artefacts such as geometry popping.As well as describing how the approach can be used in particular applications we describe the architecture and implementation of the modelling tools. Finally we show how the approach can be extended to other architectural styles and the working environment customised.

Survey of Real-Time Rendering Techniques for Crowds

Real‐time rendering of photo‐realistic humans is considerably outside the scope of current consumer‐level computer hardware. There are many techniques, which attempt to bridge the gap between what is desired and what is possible. This paper aims to give an overview of the techniques designed to alter the complexity of the models geometry (level of detail), or replace it with a flat image (visual impostor) and to improve the lighting model (lighting and shadows). Recent years have shown a boom in the power and availability of consumer‐level programmable graphics processors, thus techniques that make use of these features are coming to the forefront.

The implementation of an algorithm to find the convex hull of a set of three-dimensional points

A detailed description of the implementation of a three-dimensional convex hull algorithm is given. The problems experienced in the production and testing of a correct and robust implementation of a geometric algorithm are discussed. Attention is paid to those issues that are often brushed over in the theoretical descriptions but cause errors in a real computation. These include degeneracies such as coplanar points, floating-point errors, and other special, but not necessarily degenerate, cases.

Exploring cultural heritage sites through space and time

Traveling through a single virtual environment only tells part of the story; a particularly interesting aspect is to illustrate how an area has developed over time. This article presents a unified approach to illustrating four-dimensional data concerning a cultural heritage site. The proposed framework provides a semi-automatic approach to both reconstructing the environment and bringing all the time-dependent models into an intuitive visualization package. For each time period considered for reconstruction, the system requires a set of building footprint maps depicting the layout of the environment plus a few statistics. The statistics govern the construction of three-dimensional building models, allowing each buildings architectural style, typical building height, and roof style to be altered. This information is automatically processed and converted into a form that can be visualized. By integrating high quality landmark buildings from laser scanning or interactive modelling packages into the automatically generated scene, the cultural heritage site is realized both in a spatial and temporal context. The visualization is achieved via a 4D navigable movie which is presented using two concrete implementations written using Flash and OpenGL. The OpenGL-based implementation allows a collection of 3DS Max scenes to be automatically visualized requiring only a set of camera paths identified by the user.

Scene assembly for large scale urban reconstructions

Reconstructing large areas of historic cities involves assembling a scene from a combination of knowledge of areas that no longer exist and known monuments that have survived and can still be (at least partially) observed and measured. In many cases little detail is known for such areas although it can be anticipated that buildings in some specific generic styles would be typical of the time and place. At UEA considerable effort has been put into creating a Scene Assembler package for the CHARISMATIC project which brings together individually designed objects from detailed modelling packages such as 3DStudioMax and combines these with other more generic building prototypes. These objects are then laid out using a number of extremely powerful and user friendly operations within a landscape and sky dome. This process makes it easy and quick to put together a complete city scene, which is accurate enough, historically, to give a feel for what the area would have been like. The models constructed using the tools are intended to be used as backdrops for reconstructing historic populated events. This paper describes the stages in defining such models and the various tools available to speed up the process.

Tutorials/Surveys: Modelling trees and their interaction with the environment: A survey

In this paper, we summarize some of the techniques used for modelling certain elements of nature such as trees. We describe some of the current methods in their order of appearance in the classification spectrum given in this survey. We discuss the geometrical and biological aspects that help us to identify the position of the work in our spectrum. The paper also identifies the interaction capability of the current techniques with the environmental factors and external forces.