Level Of Detail Control Research Articles

Multi-resolution terrain rendering using summed-area tables

Due to the fundamental weaknesses of level-of-detail (LOD) control and rich details in the Geometry Clipmaps, we propose a multi-resolution terrain rendering algorithm that utilizes summed-area tables (SATs) [1] to facilitate the rendering of terrain with better geometric and shading details. First, our algorithm introduces a novel geometric error bound on the screen-based terrain rendering approach that juggles low rendering throughput and better LOD control. Geometric errors are estimated in real-time from SATs, enabling error-bounded geometry clipmap. Second, we utilize Spherical Gaussian (SG) functions to approximate lighting and bidirectional reflection distribution functions (BRDFs), and efficiently calculate outgoing radiance with self-occlusions of the terrain. SATs are utilized to enable the mipmapping of visibility and normal maps. We demonstrate the improvements of our method with experiments on accuracy and efficiency.

Appearance-driven conversion of polygon soup building models with level of detail control for 3D geospatial applications

In many 3D applications, building models in polygon-soup representation are commonly used for the purposes of visualization, for example, in movies and games. Their appearances are fine, however geometry-wise, they may have limited information of connectivity and may have internal intersections between their parts. Therefore, they are not well-suited to be directly used in 3D geospatial applications, which usually require geometric analysis. For an input building model in polygon-soup representation, we propose a novel appearance-driven approach to interactively convert it to a two-manifold model, which is more well-suited for 3D geospatial applications. In addition, the level of detail (LOD) can be controlled interactively during the conversion. Because a model in polygon-soup representation is not well-suited for geometric analysis, the main idea of the proposed method is extracting the visual appearance of the input building model and utilizing it to facilitate the conversion and LODs generation. The silhouettes are extracted and used to identify the features of the building. After this, according to the locations of these features, horizontal cross-sections are generated. We then connect two adjacent horizontal cross-sections to reconstruct the building. We control the LOD by processing the features on the silhouettes and horizontal cross-sections using a 2D approach. We also propose facilitating the conversion and LOD control by integrating a variety of rasterization methods. The results of our experiments demonstrate the effectiveness of our method.

User-assisted integrated method for controlling level of detail of large-scale B-rep assembly models

ABSTRACTIn recent times, there is a growing demand for technologies that control the level of detail (LOD) of large-scale three-dimensional (3D) computer-aided design (CAD) models. In particular, in industrial plants and in the construction industry, there is a significant need for simplification of large-scale models, because the number of models to be dealt with is tremendously large and their complexity is high. The degree of automation is, however, very low in these industries. As a result, many additional costs arise in the process of manually regenerating the 3D CAD models by the users. To resolve this problem, this study suggests a way to control effectively the LOD of large-scale B-rep assembly models. The proposed method consists of filtering, to remove those parts that ought to be removed, and progressive control, to remove sequentially the features acquired by volume decomposition. The user intervenes in the progressive control stage and adjusts the LOD for each component of the assembly. Based on the proposed method, a prototype system was implemented and experiments were performed for two test cases. The data size of the two test cases decreased, in average, to 65% in the first stage and 85% in the second stage. It was also found that the proposed component-level LOD control method is suitable and practical for a large-scale model.

Ceiba: scalable visualization of phylogenies and 2D/3D image collections.

Phylogenetic trees with hundreds of thousands of leaves are now being inferred from sequence data, posing significant challenges for visualization and exploratory analysis. Image data supplying valuable context for species in trees (and cues for exploring them) are becoming increasingly available in biodiversity databases and elsewhere but have rarely been built into tree visualization software in a scalable way. Ceiba lets the user explore large trees and inspect image collection arrays (sets of 'homologous' images) comprising mixtures of 2D and 3D image objects. Ceiba exploits recent improvements in graphics hardware, OpenGL toolkits and many standard high-performance computer graphics strategies, such as texture compression, level of detail control, culling, animations and image caching. Its tree layouts can be tuned by user-provided phylogenetic definitions of subtrees. The code has been extensively tested on phylogenies of up to 55,000 leaves and images. A manual, datasets, source code (distributed under GPL) and binaries for OS X are available at http://sourceforge.net/projects/ceiba. Supplementary data are available at Bioinformatics online.

Visualization and level-of-detail of metadata for interactive exploration of Sensor Web

There are several issues with Web-based search interfaces on a Sensor Web data infrastructure. It can be difficult to (1) find the proper keywords for the formulation of queries and (2) explore the information if the user does not have previous knowledge about the particular sensor systems providing the information. We investigate how the visualization of sensor resources on a 3D Web-based Digital Earth globe organized by level-of-detail (LOD) can enhance search and exploration of information by easing the formulation of geospatial queries against the metadata of sensor systems. Our case study provides an approach inspired by geographical mashups in which freely available functionality and data are flexibly combined. We use PostgreSQL, PostGIS, PHP, and X3D-Earth technologies to allow the Web3D standard and its geospatial component to be used for visual exploration and LOD control of a dynamic scene. Our goal is to facilitate the dynamic exploration of the Sensor Web and to allow the user to seamlessly focus in on a particular sensor system from a set of registered sensor networks deployed across the globe. We present a prototype metadata exploration system featuring LOD for a multiscaled Sensor Web as a Digital Earth application.

Rigid-body fracture sound with precomputed soundbanks

We propose a physically based algorithm for synthesizing sounds synchronized with brittle fracture animations. Motivated by laboratory experiments, we approximate brittle fracture sounds using time-varying rigid-body sound models. We extend methods for fracturing rigid materials by proposing a fast quasistatic stress solver to resolve near-audio-rate fracture events, energy-based fracture pattern modeling and estimation of "crack"-related fracture impulses. Multipole radiation models provide scalable sound radiation for complex debris and level of detail control. To reduce soundmodel generation costs for complex fracture debris, we propose Precomputed Rigid-Body Soundbanks comprised of precomputed ellipsoidal sound proxies. Examples and experiments are presented that demonstrate plausible and affordable brittle fracture sounds.

Rigid-body fracture sound with precomputed soundbanks

We propose a physically based algorithm for synthesizing sounds synchronized with brittle fracture animations. Motivated by laboratory experiments, we approximate brittle fracture sounds using time-varying rigid-body sound models. We extend methods for fracturing rigid materials by proposing a fast quasistatic stress solver to resolve near-audio-rate fracture events, energy-based fracture pattern modeling and estimation of "crack"-related fracture impulses. Multipole radiation models provide scalable sound radiation for complex debris and level of detail control. To reduce soundmodel generation costs for complex fracture debris, we propose Precomputed Rigid-Body Soundbanks comprised of precomputed ellipsoidal sound proxies. Examples and experiments are presented that demonstrate plausible and affordable brittle fracture sounds.

Supra-threshold control of peripheral LOD

Level of detail (LOD) is widely used to control visual feedback in interactive applications. LOD control is typically based on perception at threshold -- the conditions in which a stimulus first becomes perceivable. Yet most LOD manipulations are quite perceivable and occur well above threshold. Moreover, research shows that supra-threshold perception differs drastically from perception at threshold. In that case, should supra-threshold LOD control also differ from LOD control at threshold?In two experiments, we examine supra-threshold LOD control in the visual periphery and find that indeed, it should differ drastically from LOD control at threshold. Specifically, we find that LOD must support a task-dependent level of reliable perceptibility. Above that level, perceptibility of LOD control manipulations should be minimized, and detail contrast is a better predictor of perceptibility than detail size. Below that level, perceptibility must be maximized, and LOD should be improved as eccentricity rises or contrast drops. This directly contradicts prevailing threshold-based LOD control schemes, and strongly suggests a reexamination of LOD control for foveal display.

Layered lumigraph with LOD control

AbstractThe rendering performance of an image‐based rendering (IBR) system is determined by the number of images and the amount of geometrical information used. In this paper, we propose a layered lumigraph representation that is configured for optimized rendering performance based on the rendering platform (e.g., processor speed, memory) and output image resolution. The layered lumigraph is produced by classifying all pixels into a number of depth layers. Based on prior work on plenoptic sampling analysis, the layered lumigraph is constructed to achieve the same rendering quality along the minimum sampling curve by balancing the number of images and depth layers. For a given rendering platform, the best rendering performance can be obtained by choosing the optimal number of images and depth layers. Moreover, the layered lumigraph is capable of level‐of‐detail (LOD) control using the same image geometry trade‐off. Therefore, the layered lumigraph fully exploits the inherent constraints between the number of images, depth complexity, and output resolution. Finally, a backward warping technique is designed to efficiently render the layered lumigraph by taking advantage of texture mapping hardware. Copyright © 2002 John Wiley & Sons, Ltd.

Component based 3D GIS software design for the urban planning

An increasing number of users of GISs have been asking for 3D extensions for years. One popular approach for modeling 3D geo-features is to create 3D CAD model manually. In particular, manual 3D geo-feature modeling approach provides a high quality of visualization for 3D GIS features. However, this approach can be time consuming to generate 3D models being created manually and requires high costs. The design philosophies of our proposed 3D GIS software components are interoperability, standardization, reusability, adaptability and performance. We introduce a novel-modeling concept; so-called, Rule-based modeling (RBD) that can model 3D geo-features using 2D profiles and 3D feature attributes. By using rule-based engine and model library, we are able to create 3D geo-features automatically. RBD component combines a synthetic modeler with efficient LOD (level-of-detail) control for real-time rendering. In addition to, describing the details of our component, we present the comparison result between manual modeling and proposed rule-based modeling in terms of the following criteria: input data domain, interoperability, reusability and modeling cost.

Simple Blurry Reflections with Environment Maps

We present a technique which uses existing OpenGL capabilities to approximate the effect of blurry specular reflections and indirect diffuse illumination. It makes use of environment maps, mipmapping with level of detail control, and possibly texture borders. The method is extremely simple to implement, in some cases requiring just a single additional OpenGL statement.