A Sparse Voxel Octree-Based Framework for Computing Solar Radiation Using 3D City Models

abstract: An effective three-dimensional (3D) data representation is required to assess the spatial distribution of the photovoltaic potential over urban building roofs and facades using 3D city models. Voxels have long been used as a spatial data representation, but practical applications of the voxel representation have been limited compared with rasters in traditional two-dimensional (2D) geographic information systems (GIS). We propose to use sparse voxel octree (SVO) as a data representation to extend the GRASS GIS r.sun solar radiation model from 2D to 3D. The GRASS GIS r.sun model is nested in an SVO-based computing framework. The presented 3D solar radiation computing framework was applied to 3D building groups of different geometric complexities to demonstrate its efficiency and scalability. We presented a method to explicitly compute diffuse shading losses in r.sun, and found that diffuse shading losses can reduce up to 10% of the annual global radiation under clear sky conditions. Hence, diffuse shading losses are of significant importance especially in complex urban environments

Real-time screen space reflections and refractions using sparse voxel octrees

This thesis explores the data structure known as sparse voxel octree and how it can improve the performance of real-time ray tracing. While ray tracing is an excellent way of producing realistic effects in computer graphics it is also very computationally heavy. Its use in real-time applications such as games and simulators is therefore limited since the hardware must be able to render enough frames per second to satisfy the users. The purpose of an octree is to reduce the amount of intersection tests each ray needs significantly. This thesis will explain the many challenges when implementing and using an octree, and also how to solve them. This includes both how to build the tree using various tests and then also how to use it with a ray tracer to produce reflections and refractions in real time

Streaming visualisation of quantitative mass spectrometry data based on a novel raw signal decomposition method

As data rates rise, there is a danger that informatics for high-throughput LC-MS becomes more opaque and inaccessible to practitioners. It is therefore critical that efficient visualisation tools are available to facilitate quality control, verification, validation, interpretation, and sharing of raw MS data and the results of MS analyses. Currently, MS data is stored as contiguous spectra. Recall of individual spectra is quick but panoramas, zooming and panning across whole datasets necessitates processing/memory overheads impractical for interactive use. Moreover, visualisation is challenging if significant quantification data is missing due to data-dependent acquisition of MS/MS spectra. In order to tackle these issues, we leverage our seaMass technique for novel signal decomposition. LC-MS data is modelled as a 2D surface through selection of a sparse set of weighted B-spline basis functions from an over-complete dictionary. By ordering and spatially partitioning the weights with an R-tree data model, efficient streaming visualisations are achieved. In this paper, we describe the core MS1 visualisation engine and overlay of MS/MS annotations. This enables the mass spectrometrist to quickly inspect whole runs for ionisation/chromatographic issues, MS/MS precursors for coverage problems, or putative biomarkers for interferences, for example. The open-source software is available from http://seamass.net/viz/

Renderização 3D usando árvores esparsas de voxels

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Ciências da Computação.A representação e renderização de modelos 3D em computador é feita tradicionalmente empregando polígonos, que representam uma superfície. Este trabalho apresenta uma forma de construir e visualizar modelos tridimensionais com dados volumétricos em vez de superficiais. A estrutura de dados desenvolvida armazena unidades chamadas voxels, – equivalentes 3D a pixels – dispostas em uma árvore de subdivisão espacial conhecida como octree. O armazenamento particionado poupa espaço em memória ao reduzir informações redundantes e permite executar a renderização de forma eficiente com a técnica de ray tracing. Também é mostrada uma interface intuitiva para a criação e visualização de volumes, com exemplos práticos em alguns domínios. Apesar de representar um novo método de criação e representação de objetos 3D de forma mais intuitiva, o modelo de voxels ainda tem poucas aplicações, salvo em meio acadêmico. Este trabalho tem como objetivo desenvolver um renderizador eficiente, baseado em voxels, acelerado em GPU, e fácil de usar em diferentes áreas e plataformas. Para esse fim, uma aplicação visualizadora de modelos volumétricos em tempo real usando OpenGL foi desenvolvida

PSVDAG: Compact Voxelized Representation of 3D Scenes Using Pointerless Sparse Voxel Directed Acyclic Graphs

This paper deals with the issue of geometry representation of voxelized three-dimensional scenes using hierarchical data structures. These include pointerless Sparse Voxel Octrees that have no pointers on child nodes and allow a compact binary representation. However, if necessary, there is a possibility to reconstruct these pointers for rapid traversing. Sparse Voxel Directed Acyclic Graphs added 32-bit pointers to child nodes and merging of common subtrees, which can be considered lossless compression. By merging common subtrees, no decompression overhead occurs at the time of traversing. The hierarchical data structure proposed herein - the Pointerless Sparse Voxel Directed Acyclic Graph - incorporates the benefits of both - pointerless Sparse Voxel Octrees (by avoiding storing pointers on child nodes) and Sparse Voxel Directed Acyclic Graphs (by allowing the merging of common subtrees due the introduction of labels and callers). The proposed data structure supports the quick and easy reconstruction of pointers by introducing the Active Child Node Count. It also potentially allows Child Node Mask compression of its nodes. This paper presents the proposed data structure and its binary-level encoding in detail. It compares the effectiveness of the representation of voxelized three-dimensional scenes (originally represented in OBJ format) in the proposed data structure with the data structures mentioned above. It also summarizes statistical data providing a more detailed description of the various parameters of the data structure for different scenes stored in multiple resolutions