We present a new rendering technique for processing multiple multiresolution textures of LOD terrain models and describe its application to interactive, animated terrain content design. The approach is based on a multiresolution model for terrain texture which cooperates with a multiresolution model for terrain geometry. For each texture layer, an image pyramid and a texture tree are constructed. Multiple texture layers can be associated with one terrain model and can be combined in different ways, e.g., by blending and masking. The rendering algorithm traverses simultaneously the geometry multiresolution model and the texture multiresolution model, and takes into account geometric and texture approximation errors. It uses multi-pass rendering and exploits multitexturing to achieve real-time performance. Applications include interactive texture lenses, texture animation, and topographic textures. These techniques offer an enormous potential for developing new visualization applications...

this paper we introduce a new approach to realistic rendering at interactive rates on commodity graphics hardware. The approach uses efficient perceptual metrics within a decision theoretic framework to optimally order rendering operations, producing images of the highest visual quality within system constraints. We demonstrate the usefulness of this approach for various applications such as diffuse texture caching, environment map prioritization and radiosity mesh simplification. Although here we address the problem of realistic rendering at interactive rates, the perceptually-based decision theoretic methodology we introduce can be usefully applied in many areas of computer graphics

The performance of hardware-based interactive rendering systems is often constrained by polygon fill rates and texture map capacity, rather than polygon count alone. We present a new software texture caching algorithm that optimizes the use of texture memory in current graphics hardware by dynamically allocating more memory to the textures that have the greatest visual importance in the scene. The algorithm employs a resource allocation scheme that decides which resolution to use for each texture in board memory. The allocation scheme estimates the visual importance of textures using a perceptually-based metric that takes into account view point and vertex illumination as well as texture contrast and frequency content. This approach provides high frame rates while maximizing image quality.

. Realistic rendering of outdoor terrain requires both that the geometry of the environment be modeled accurately and that appropriate texturing by laid down on top of that geometry. While elevation data is widely available for much of the world and many methods exist for converting this data to forms suitable for graphics systems, we have much less experience with patterning the resulting surface. This paper describes an approach for using panchromatic aerial imagery to produce color views of alpine scenes. The method is able to remove shading and shadowing effects in the original image so that shading and shadowing appropriate to variable times of day can be added. Seasonal snow cover can be added in a physically plausible manner. Finally, 3--D instancing of trees and brush can be added in locations consistent with the imagery, significantly improving the visual quality. 1 Introduction Sophisticated techniques exist for converting real-world elevation data into a terrain...

We have developed a hierarchical paging scheme for handling very large volumetric data sets at interactive frame rates. Our system trades texture resolution for speed and uses effective prediction strategies. We have tested our approach for datasets with up to 16GB in size and show that it works well with less than 500MB of main memory. Our approach makes it feasible to deal with these volumes on desktop machines.

We present a new terrain decimation technique called a Quadtree Morph, or Q-morph. The new approach eliminates the usual popping artifacts associated with polygon reduction, replacing them with less objectionable smooth morphing. We show that Q-morphing is fast enough to create a view-dependent terrain model for each frame in an interactive environment. In contrast to most Geomorph algorithms, Q-morphing does not use a time step to interpolate between geometric configurations. Instead, the geometry motion in a Q-morph is based solely on the position of the viewer.

Video games and simulators commonly use very detailed textures, whose cumulative size is often larger than the GPU memory. Textures may be loaded progressively, but dynamically loading and transferring this large amount of data in GPU memory results in loading delays and poor performance. Therefore, managing texture memory has become an important issue. While this problem has been (partly) addressed early for the specific case of terrain rendering, there is no generic texture management system for arbitrary meshes. We propose such a system, implemented on today’s GPUs, which unifies classical solutions aimed at reducing memory transfer: progressive loading, texture compression, and caching strategies. For this, we introduce a new algorithm – running on GPU – to solve the major difficulty of detecting which parts of the texture are required for rendering. Our system is based on three components manipulating a tile pool which stores texture data in GPU memory. First, the Texture Load Map determines at every frame the appropriate list of texture tiles (i.e. location and MIP-map level) to render from the current viewpoint. Second, the Texture Cache manages the tile pool. Finally, the Texture Producer loads and decodes required texture tiles

Abstract—A mathematical model is presented for comparing geometric and image-based simplification methods. Geometric simplification reduces the number of polygons in the virtual object and image-based simplification replaces the object with an image. Our model integrates and extrapolates existing accuracy estimates, enabling the comparison of different simplification methods in order to choose the most efficient method in a given situation. The model compares data transfer and rendering load of the methods. Byte size and expected lifetime of simplifications are calculated as a function of the desired visual quality and the position and movement of the viewer. An example result is that, in typical viewing and rendering conditions and for objects with a radius in the order of one meter, imposter techniques can be used at viewing distances above 15 meters. Below that, simplified polygon objects are required and, below one meter distance, the full-resolution virtual object has to be rendered. An electronic version of the model is available on the web. Index Terms—Real-time rendering, dynamic geometry simplification, imposters, resource load, thin client, mathematical model. æ 1

One of the major masterpieces of international Gothic art (1350-1450) is located in the Aquila tower in Buonconsiglio castle, Trento, Italy. The main room in the tower is completely frescoed with the Cycle of the Months, a rare example of medieval painting on a nonreligious subject. The frescos depict medieval time month by month with stunning details of the landscape, costumes, and every element of daily life. As part of the PEACH (Personal Experience with Active Cultural Heritage) project, the objective of this work is to acquire the most suitable data and generate a textured 3D model for interactive manipulation and creation of a photo-realistic walkthrough movie. This will give a vista to scientists, conservationists, historians, and visitors for looking at and studying this room and its frescos in virtual reality. Since photo-realism of the frescos is of utmost importance, it became apparent that many issues related to geometric and radiometric distortions must be addressed. For example, texture data is typically collected as images containing specific lighting conditions. When these images are stitched together, discontinuities are usually visible. Another predicament is the real-time requirement of visualisation and manipulation of 3D models. Since it is important to maintain the best texture quality to visualize the details of the frescos and at the same time have smooth interactive visualization, memory problems had to be addressed. We build upon existing techniques developed for texture acquisition and reconstruction to generate efficient maps of high visual quality. Results of the first phase of the project are presented. 1.1 Objectives of the Project 1.

Abstract — This paper describes a geospatial information system (GIS) that can be used for several mission-critical activities, such as management of risky activities, and urban planning. The main novelty of this system, stands on the ability to analyze and present data inside a 3D media-rich geo-referenced environment. The 3D user interface suggested is based on the idea of interoperable processing units that can be directly manipulated and linked to create complex process chains; thus, freeing the operator from unnecessary information or constraints on the analytic reasoning. Additionally, users can use this interface to visually program and deploy web accessible algorithms. This is an important aspect within collaborative activities, where is often necessary to create new bridges between different knowledge areas in response to unexpected situations.