Geometric transformations in octrees using shears

Existent algorithms to perform geometric transformations on octrees can be classified in two families: inverse transformation and address computation ones. Those in the inverse transformation family essentially resample the target octree from the source one, and are able to cope with all the affine transformations. Those in the address computation family only deal with translations, but are commonly accepted as faster than the former ones for they do no intersection tests, but directly calculate the transformed address of each black node in the source tree. This work introduces a new translation algorithm that shows to perform better than previous one when very small displacements are involved. This property is particularly useful in applications such as simulation, robotics or computer animation.Postprint (published version

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/

The Visibility Octree. A Data Structure for 3D Navigation

This paper describes the Visibility Octree, a data structure to accelerate 3D navigation through very complex scenes. A conservative visibility algorithm that computes and hierarchically stores the structure at a preprocessing stage is presented. The Visibility Octree is used during navigation and its main contribution is its ability to provide an effective control over the coarseness of the visibility approximation. Tests with indoor ship scenes show that the visibility octree performs well on densely occluded environments. 1 Introduction and previous work This work is focused on the interactive navigation through very complex polygonal models. There are a wide range of applications nowadays whose requirements surpass even the most expensive high-end graphics workstations. To name a few, ship design, architectural design and virtual reality applications have hundreds of thousands or even millions of polygons. Current graphics hardware is not able to cope with these kind of scenes at ..

Data Structures and Algorithms for Navigation in Highly Polygon-Populated Scenes

We present the visibility octree, a new data structure to accelerate 3D navigation through very complex scenes. Our approach employs a conservative visibility technique to compute an approximation to the visibility space partition. This approximation is computed and stored hierarchically at a preprocessing stage. We believe its main contribution to be its ability to provide an effective control over the coarseness of the approximation. A preliminary test with some randomly generated indoor scenes seems to show that the visibility octree will perform well on densely occluded scenes. 1 Introduction This work is focused on the interactive navigation through polygonal models. There is a wide range of applications nowadays whose requirements surpass even the most expensive high-end graphics workstations. To name a few, ship design, architectural design and virtual reality applications have hundreds of thousands or even millions of polygons. Current graphics hardware is not able to cope wit..

LOD Visibility Culling and Occluder Synthesis

Level-of-detail occlusion culling is a novel approach to the management of occluders that can be easily integrated into most current visibility culling algorithms. The main contribution of this paper is an algorithm that automatically generates sets of densely overlapping boxes with enhanced occlusion properties from non-convex subsets. We call this method occluder synthesis because it is not sensitive to the way the objects are tesselated but to the space enclosed by them. The extension of this technique by allowing a bounded amount of image error is also discussed. We show that visibility computations can be based on a multiresolution model which provides several representations of these occluders with varying visibility accuracy. Our tests show that occlusion performance in tesselated scenes is improved severely even if no imageerror is allowed. 1 Introduction Real-time inspection of very large models, with hundreds of thousands of faces, often surpasses the hardware performance o..

Geometric transformations in octrees using shears

Existent algorithms to perform geometric transformations on octrees can be classified in two families: inverse transformation and address computation ones. Those in the inverse transformation family essentially resample the target octree from the source one, and are able to cope with all the affine transformations. Those in the address computation family only deal with translations, but are commonly accepted as faster than the former ones for they do no intersection tests, but directly calculate the transformed address of each black node in the source tree. This work introduces a new translation algorithm that shows to perform better than previous one when very small displacements are involved. This property is particularly useful in applications such as simulation, robotics or computer animation

The Visibility octree. A data structure for 3D navigation

This paper describes the Visibility Octree, a data structure to accelerate 3D navigation through very complex scenes. A conservative visibility algorithm that computes and hierarchically stores the structure at a preprocessing stage is presented. The Visibility Octree is used during navigation and its main contribution is its ability to provide an effective control over the coarseness of the visibility approximation. Tests with indoor ship scenes show that the visibility octree performs well on densely occluded environments