This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic.

A reflectance model for computer graphics

Augmented reality applications in design and manufacturing

In the last decades, 3D city models appear to have been predominantly used for visualisation; however, today they are being increasingly employed in a number of domains and for a large range of tasks beyond visualisation. In this paper, we seek to understand and document the state of the art regarding the utilisation of 3D city models across multiple domains based on a comprehensive literature study including hundreds of research papers, technical reports and online resources. A challenge in a study such as ours is that the ways in which 3D city models are used cannot be readily listed due to fuzziness, terminological ambiguity, unclear added-value of 3D geoinformation in some instances, and absence of technical information. To address this challenge, we delineate a hierarchical terminology (spatial operations, use cases, applications), and develop a theoretical reasoning to segment and categorise the diverse uses of 3D city models. Following this framework, we provide a list of identified use cases of 3D city models (with a description of each), and their applications. Our study demonstrates that 3D city models are employed in at least 29 use cases that are a part of more than 100 applications. The classified inventory could be useful for scientists as well as stakeholders in the geospatial industry, such as companies and national mapping agencies, as it may serve as a reference document to better position their operations, design product portfolios, and to better understand the market.

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Applications of 3D City Models: State of the Art Review

Displaying network content searches on mobile devices involves obtaining results of a network content request via a mobile device. A geolocation of at least one object associated with the results of the network content request is also obtained. A scene is viewed in a camera view of the mobile device. A virtual location is determined in the camera view. The virtual location represents the actual location of the object relative to the scene contained in the camera view. A graphic representing the object is then displayed at the virtual location in the camera view.

Displaying network objects in mobile devices based on geolocation

The use of stochastic texture for the visualization of scalar and vector fields over surfaces is discussed. Current techniques for texture synthesis are not suitable, because they do not provide local control, and are not suited for the design of textures. A new technique, spot noise, is presented that does provide these features. Spot noise is synthesized by addition of randomly weighted and positioned spots. Local control of the texture is realized by variation of the spot. The spot is a useful primitive for texture design, because, in general, the relations between features of the spot and features of the texture are straightforward. Various examples and applications are shown. Spot noise lends itself well for the synthesis of texture over curved surfaces, and is therefore an alternative to solid texturing. The relations of spot noise with a variety of other techniques, such as radom faults, filtering, sparse convolution, and particle systems, are discussed. It appears that spot noise provides a new perspective on those techniques.

Spot noise texture synthesis for data visualization

Feature modelling and conversion: key concepts to concurrent engineering

To support 3D GIS interaction within VR-environments we propose a multi-view approach based on three types of visualization: plan view, model view and world view. The visualization in these views ranges from a conventional map, through a partly symbolic and simplified 3D representation to a full immersive and photo-realistic 3D display. The views can be used simultaneously or intermittently, and each provides a repertoire of interaction possibilities that are apt but not necessarily limited to that view. We are currently developing a 3D GIS&VR system (Karma VI) based on existing GIS and VR technology that uses the three views to support the design, development and presentation of large infrastructure plans in The Netherlands. Operational use of this system showed that the multi-view approach leads to a more sophisticated understanding of those plans.

Interaction in virtual world views-linking 3D GIS with VR

Methods to improve the efficiency of the ray tracing process are reviewed. Special attention is given to algorithms for tracing a ray through box and cell structures of hierarchical box and spatial subdivision methods.

Data structures for ray tracing

Ray tracing is a powerful technique to generate realistic images of 3D scenes. However, rendering complex scenes may easily exceed the processing and memory capabilities of a single workstation. Distributed processing offers a solution if the algorithm can be parallelized in an efficient way. In this paper a hybrid scheduling approach is presented that combines demand driven and data parallel techniques. Which tasks to process demand driven and which data parallel, is decided by the data intensity of the task and the amount of data locality (coherence) that will be present in the task. By combining demand driven and data driven tasks, a better load balance may be achieved, while at the same time the communication is spread evenly across the network. This leads to a scalable and efficient parallel implementation of the ray tracing algorithm with little restriction on the size of the model data base to be rendered.

Frederik W. Jansen

Papers

Feature modelling and conversion: key concepts to concurrent engineering

Interaction in virtual world views-linking 3D GIS with VR

Data structures for ray tracing

Rendering large scenes using parallel ray tracing

A multi-view VR interface for 3D GIS