Planet-Sized Batched Dynamic Adaptive Meshes (P-BDAM)

This paper describes an efficient technique for out-of-core management and interactive rendering of planet sized textured terrain surfaces. The technique, called planet-sized batched dynamic adaptive meshes (P-BDAM), extends the BDAM approach by using as basic primitive a general triangulation of points on a displaced triangle. The proposed framework introduces several advances with respect to the state of the art: thanks to a batched host-to-graphics communication model, we outperform current adaptive tessellation solutions in terms of rendering speed; we guarantee overall geometric continuity, exploiting programmable graphics hardware to cope with the accuracy issues introduced by single precision floating points; we exploit a compressed out of core representation and speculative prefetching for hiding disk latency during rendering of out-of-core data; we efficiently construct high quality simplified representations with a novel distributed out of core simplification algorithm working on a standard PC network.147-15

Survey of semi-regular multiresolution models for interactive terrain rendering

Rendering high quality digital terrains at interactive rates requires carefully crafted algorithms and data structures able to balance the competing requirements of realism and frame rates, while taking into account the memory and speed limitations of the underlying graphics platform. In this survey, we analyze multiresolution approaches that exploit a certain semi-regularity of the data. These approaches have produced some of the most efficient systems to date. After providing a short background and motivation for the methods, we focus on illustrating models based on tiled blocks and nested regular grids, quadtrees and triangle bin-trees triangulations, as well as cluster-based approaches. We then discuss LOD error metrics and system-level data management aspects of interactive terrain visualization, including dynamic scene management, out-of-core data organization and compression, as well as numerical accurac

External-Memory Algorithms for Processing Line Segments in Geographic Information Systems

The original publication is available at www.springerlink.comIn the design of algorithms for large-scale applications it is essential to consider the problem of minimizing I/O communication. Geographical information systems (GIS) are good examples of such large-scale applications as they frequently handle huge amounts of spatial data. In this paper we develop e cient new external-memory algorithms for a number of important problems involving line segments in the plane, including trapezoid decomposition, batched planar point location, triangulation, red-blue line segment intersection reporting, and general line segment intersection reporting. In GIS systems, the rst three problems are useful for rendering and modeling, and the latter two are frequently used for overlaying maps and extracting information from them

Simulating Populations in Massive Urban Environments

This short paper reviews some of the results obtained withing the European Project CRIMSON.The United Nations recently reported that the global proportion of urban population reached 49% in 2005 and that 60% of the global population is expected to live in cities by 2030. Urbanised areas are extremely vulnerable to all sorts of threats. Indeed, the combination of heavy population concentrations, critical infrastructures and built environments make it possible for environmental, industrial or man-made incidents to rapidly escalate into major disorders. Recent events have forcefully demonstrated that authorities at all levels of government turn out to be inadequately prepared for the intricacies and dilemmas of disasters in large urban environments. Therefore, innovative tools are needed to assist them in the studies, planning and inter-organizational preparation efforts, enabling to understand vulnerabilities and security issues, define and assess crisis management procedures, and train personnel. The CRIMSON research project has been funded by the European Commission in the field of Security Research to address this challenging need by researching, implementing and validating an innovative framework combining the latest virtual reality and simulation technologies. For that purpose, several technological challenges have been tackled by an international team of researchers, industrials and users, and important advances have been made in the following fields

Route Planning in Transportation Networks

We survey recent advances in algorithms for route planning in transportation networks. For road networks, we show that one can compute driving directions in milliseconds or less even at continental scale. A variety of techniques provide different trade-offs between preprocessing effort, space requirements, and query time. Some algorithms can answer queries in a fraction of a microsecond, while others can deal efficiently with real-time traffic. Journey planning on public transportation systems, although conceptually similar, is a significantly harder problem due to its inherent time-dependent and multicriteria nature. Although exact algorithms are fast enough for interactive queries on metropolitan transit systems, dealing with continent-sized instances requires simplifications or heavy preprocessing. The multimodal route planning problem, which seeks journeys combining schedule-based transportation (buses, trains) with unrestricted modes (walking, driving), is even harder, relying on approximate solutions even for metropolitan inputs.Comment: This is an updated version of the technical report MSR-TR-2014-4, previously published by Microsoft Research. This work was mostly done while the authors Daniel Delling, Andrew Goldberg, and Renato F. Werneck were at Microsoft Research Silicon Valle

Real-time tessellation of terrain on graphics hardware

Synthetic terrain is a key element in many applications, which can lessen the sense of realism if it is not handled correctly. We propose a new technique for visualizing terrain surfaces by tessellating them on the GPU. The presented algorithm introduces a new adaptive tessellation scheme for managing the level of detail of the terrain mesh, avoiding the appearance of t-vertices that can produce visually disturbing artifacts. Previous solutions exploited the geometry shader's capabilities to tessellate meshes from scratch. In contrast, we reuse the already calculated data to minimize the operations performed in the shader units. This feature allows us to increase performance through smart refining and coarsening. Finally, we also propose a framework to manage large DEMs as height maps.This work has been supported by the Spanish Ministry of Science and Technology (projects TIN2009-14103-C03-03, TSI-020400-2009-0133 and TIN2010-21089-C03-03), by the Generalitat Valenciana (project PROMETEO/2010/028), by Bancaja (project P1 1B2010-08) and by ITEA2 (project IP08009