Real-time Terrain Mapping

We present an interactive, real-time mapping system for digital elevation maps (DEMs), which allows Earth scientists to map and therefore understand the deformation of the continental crust at length scales of 10m to 1000km. Our system visualizes the surface of the Earth as a 3D~surface generated from a DEM, with a color texture generated from a registered multispectral image and vector-based mapping elements draped over it. We use a quadtree-based multiresolution method to be able to render high-resolution terrain mapping data sets of large spatial regions in real time. The main strength of our system is the combination of interactive rendering and interactive mapping directly onto the 3D~surface, with the ability to navigate the terrain and to change viewpoints arbitrarily during mapping. User studies and comparisons with commercially available mapping software show that our system improves mapping accuracy and efficiency, and also enables qualitatively different observations that are not possible to make with existing systems

LOCALIS: Locally-adaptive Line Simplification for GPU-based Geographic Vector Data Visualization

Visualization of large vector line data is a core task in geographic and cartographic systems. Vector maps are often displayed at different cartographic generalization levels, traditionally by using several discrete levels-of-detail (LODs). This limits the generalization levels to a fixed and predefined set of LODs, and generally does not support smooth LOD transitions. However, fast GPUs and novel line rendering techniques can be exploited to integrate dynamic vector map LOD management into GPU-based algorithms for locally-adaptive line simplification and real-time rendering. We propose a new technique that interactively visualizes large line vector datasets at variable LODs. It is based on the Douglas-Peucker line simplification principle, generating an exhaustive set of line segments whose specific subsets represent the lines at any variable LOD. At run time, an appropriate and view-dependent error metric supports screen-space adaptive LOD levels and the display of the correct subset of line segments accordingly. Our implementation shows that we can simplify and display large line datasets interactively. We can successfully apply line style patterns, dynamic LOD selection lenses, and anti-aliasing techniques to our line rendering

Algorithms for sketching surfaces

CISRG discussion paper ; 1

Terrestrial laser scanning and 3D imaging: Heritage case study – The Black Gate, Newcastle Upon Tyne

This paper offers a case study on the recording of a section of wall on a complex heritage building, the Black Gate in Newcastle upon Tyne. The paper adopts case study methodology to assess the appropriateness of using a long range scanner based upon pulse technology for the recording of part of this historic structure and describes the scanning instruments adopted as well as the selection of appropriate software for the pre-processing and documentation. The study offers an overview of the survey planning stages, field operation, and processing of 3D point cloud data using the third party software adopted, including problems encountered. Issues emerging are discussed, in both the 2D and 3D modelling of detailed surfaces from point cloud data, and in the process of software selection, data preparation and export, pre-processing of point cloud data, meshing and the creation of 2D geometry and 3D animations. The paper describes the end results offered as deliverables for this project, and offers recommendations for a working method that can produce data suitable for producing stone-by-stone elevation drawings. The work processes and cost / time indicators are included in this case study and conclusions will consider whether the technique adopted could lead to an improved solution for heritage recording compared to those traditional techniques which are currently employed to produce stone-by-stone elevations. Areas for future research are identified

Practical line rasterization for multi-resolution textures

Draping 2D vectorial information over a 3D terrain elevation model is usually performed by real-time rendering to texture. In the case of linear feature representation, there are several specific problems using the texturing approach, specially when using multi-resolution textures. These problems are related to visual quality, aliasing artifacts and rendering performance. In this paper, we address the problems of 2D line rasterization on a multi-resolution texturing engine from a pragmatical point of view; some alternative solutions are presented, compared and evaluated. For each solution we have analyzed the visual quality, the impact on the rendering performance and the memory consumption. The study performed in this work is based on an OpenGL implementation of a clipmap-based multi-resolution texturing system, and is oriented towards the use of inexpensive consumer graphics hardware. 1

An open source virtual globe rendering engine for 3D applications: NASA World Wind

Background NASA World Wind is an open source application-programming interface for developing geographic information systems based on a virtual globe rendering engine representing a planet. NASA World Wind provides the ideal environment for scientific data, their analysis, visual representation and interaction with users, in a single platform, which can be deployed both as a Java desktop application (NASA World Wind) or a JavaScript web application (ESA-NASA Web World Wind). Results We give here an overview of the project, reporting details regarding current development direction, with state of the art examples. The European Space Agency is now partnering with NASA on development of the "ESA-NASA Web World Wind"; this high degree of interest from other agencies will boost future project productivity. Conclusions With this contribution, we want to increase awareness of NASA World Wind as a unique opportunity to foster collaboration between scientists, developers and other stakeholders, enriching knowledge of our Earth’s complexity

3D visualisation of the laetoli footprints on the internet

Bibliography: p. 84-86