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1

Automatic portal generation for 3d audio – from triangle soup to a portal system

Turecki P., Pędzimąż T., Pałka S., Ziółko B.

Computer Science

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2016

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Vol. 17 (3)

321--352

EN

The purpose of this paper is to investigate an algorithm for generating an auto- matic portal system. This has been accomplished based on a given set of trian- gles. The proposed solution was designed to enhance the performance of a sound beam-tracing engine. This solution can also be used for other areas where portal systems are applicable. The provided technical solution emphasizes the beam tracing engine’s requirements. Our approach is based on the work of Haumont et al. (with additional improvements), resulting in improved scene segmenta- tion and lower computational complexity. We examined voxelization techniques and their properties, and have adjusted these to fit the requirements of a beam- tracing engine. As a result of our investigation, a new method for finding portal placement has been developed by adjusting the orientation of the found portals to fit the neighboring scene walls. In addition, we replaced Haumont et al.’s prevoxelization step, which is used for erasing geometrical details (for exam- ple, thin walls). This was done by smoothing the distance field that, in effect, eliminated incorrectly positioned portals. The results of our work remove the requirement for walls that separate rooms to have a particular thickness. We al- so describe a method for building a structure that accelerates real-time queries for determining the area where a given point is located. All of the presented techniques allow for the use of larger sized voxels, which increases performance and reduces memory requirements (not only during the preprocessing phase but also during real-time usage). The proposed solutions were tested using scenarios with scenes of varying complexity.

2

Region-based processing of volumetric data

Hućko M., Śramek M.

Journal of Medical Informatics & Technologies

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2011

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Vol. 17

247--253

EN

Measurement of volumetric tomographic data, similar to other measurement techniques, suffers from several classes of artifacts, of which noise presence and the partial volume effect belong to the most prominent ones. These artifacts spoil data analysis and/or visualization, which may, for example in the case of medical imaging, lead to erroneous decisions with severe consequences. We propose a set of tools for region-based processing of volumetric data. Here, the basic entity is a spectrally homogeneous region instead of the traditional voxel. This provides for, on the one hand, higher robustness and, on the other hand, speeds up processing owing to many times smaller amount of elements to work with. Homogeneous regions are in our approach detected by the well-known segmentation by means of the watershed transform. In this paper we present algorithms for streamed computation of watershed transform, which allows for processing of very large data, region-based data smoothing and region merging based on the spectral distance. Further, we present an interactive tool for volume data segmentation and visualization which takes advantage of region hierarchies obtained by a hierarchical watershed transform.

3

The watershed transform: definitions, algorithms and parallelization strategies

Roerdink Jos B.T.M., Meijster A.

Fundamenta Informaticae

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2000

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Vol. 41, Nr 1,2

187-228

EN

The watershed transform is the method of choice for image segmentation in the field of mathematical morphology. We present a critical review of several definitions of the watershed transform and the associated sequential algorithms, and discuss various issues which often cause confusion in the literature. The need to distinguish between definition, algorithm specification and algorithm implementation is pointed out. Various examples are given which illustrate differences between watershed transforms based on different definitions and/or implementations. The second part of the paper surveys approaches for parallel implementation of sequential watershed algorithms