Exploring mesh shaders

Dissertação de mestrado integrado em Engenharia InformáticaEvery artist is somewhat limited by the mean by which they expose their art. This is also true for the field of Computer Graphics, where there are many limiting factors that developers must go out of their way to avoid. The most limiting of these factors is the computing performance, which directly limits the complexity of what an artist can fabricate in a piece of hardware. As such, Computer Graphics’ investigators keep an eye out for the improvements made in the hardware department that enables them to introduce more complexity to the scenes they create on their computers. Three years ago, a novel approach to compute the geometric complexity of three-dimensional (3D) scenes was introduced: Mesh shaders. Mesh shaders pose as an alternative to the traditional geometric processing method and can be a more performant approach to handle specific geometric workloads. Notwithstanding, little attention has been given to these shaders. Thus, this thesis presents an investigative effort to evaluate the value proposition of these shaders across different scenarios. To do so, this thesis puts Mesh shaders against traditional implementations and measures their differences both in method and performance. By the end of this thesis, the reader should have a concise understanding of Mesh shaders, but not a clear cut answer regarding their use. These shaders can provide performance benefits in specific scenarios over the traditional approach, but not without considerable care by the developer. In fact, the flexibility provided by the Mesh shaders’ approach gives the developer a significant responsibility regarding their final performance. When incorrectly set up, these shaders can result in mediocre performances compared to those of the traditional pipeline. Ultimately, these shaders should be used by experienced users intending to avoid specific bottlenecks of the traditional approach. For others, the traditional pipeline offers a more streamlined approach, thoroughly optimised by default.Todos os artistas são de alguma forma limitados pelo meio de exposição da sua arte. Isto não deixa de ser verdade com Computação Gráfica, onde existem vários fatores limitadores que os programadores têm de con tornar. Entre estes, o mais impeditivo é a velocidade de computação, que limita diretamente a complexidade da arte que pode ser produzida por uma peça de hardware. Deste modo, os investigadores da área de Computação Gráfica mantêm-se atentos às inovações que ocorrem no campo do hardware e lhes permitem introduzir mais complexidade nos cenários que criam. Há três anos, um método inédito para tratar a complexidade geométrica de cenas tridimensionais foi intro duzido: Mesh shaders. Os Mesh shaders apresentam-se como uma alternativa ao método tradicional de pro cessamento de geometria, que pode obter melhor desempenho em certos cenários geométricos. No entanto, não tem sido dada muita atenção a esta alternativa. Assim, esta tese apresenta uma investigação destes shaders com o intuito de avaliar a sua proposta de valor em diferentes situações. Para o fazer, esta tese irá colocar estes shaders frente a frente com os shaders tradicionais e medirá as diferenças entre ambos, tanto em desempenho como em método. No final, o leitor deverá possuir uma ideia coesa sobre os Mesh shaders, mas não terá uma perceção binária quanto ao uso dos mesmos. Isto porque estes shaders podem oferecer um benefício em termos de desempenho em certas situações, mas requerem cuidados adicionais por parte do programador. Da flexibilidade oferecida pelos Mesh shaders advém uma responsabilidade significativa para o programador no que toca ao desempenho final dos mesmos. Quando programados incorretamente, estes shaders resultarão num desempenho medíocre comparado ao desempenho oferecido pelo método tradicional. Fundamentalmente, estes shaders deverão ser utilizados por utilizadores mais experientes que pretendem evitar bottlenecks específicos do método tradicional. Para todos os outros, o pipeline tradicional oferece um método mais simples que possui por predefinição otimizações acentuadas

Spectral/hp element methods: recent developments, applications, and perspectives

The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials, modified to accommodate C0-continuous expansions. Computationally and theoretically, by increasing the polynomial order p, high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use the spectral/hp element method in transitional flows and ocean engineering. Finally, some of the major challenges to be overcome in order to use the spectral/hp element method in more complex science and engineering applications are discussed

Migration of Moorish Design and Its Cultural Influences in Andalusia

This research was supported by the Undergraduate Research Opportunities Program (UROP)

Protomelission is an early dasyclad alga and not a Cambrian bryozoan

The animal phyla and their associated body plans originate from a singular burst of evolution occurring during the Cambrian period, over 500 million years ago1. The phylum Bryozoa, the colonial ‘moss animals’, have been the exception: convincing skeletons of this biomineralizing clade have been absent from Cambrian strata, in part because potential bryozoan fossils are difficult to distinguish from the modular skeletons of other animal and algal groups2,3. At present, the strongest candidate4 is the phosphatic microfossil Protomelission5. Here we describe exceptionally preserved non-mineralized anatomy in Protomelission-like macrofossils from the Xiaoshiba Lagerstätte6. Taken alongside the detailed skeletal construction and the potential taphonomic origin of ‘zooid apertures’, we consider that Protomelission is better interpreted as the earliest dasycladalean green alga—emphasizing the ecological role of benthic photosynthesizers in early Cambrian communities. Under this interpretation, Protomelission cannot inform the origins of the bryozoan body plan; despite a growing number of promising candidates7,8,9, there remain no unequivocal bryozoans of Cambrian age

The Aspects of Efficient Dynamic Configurations in Architecture

The elements and means affecting the formulation and structure of the architectural buildings have been greatly developed by man throughout different ages according to the development of technology, so the dimensions and specifications of configuring dynamic buildings can be designed and controlled in order to leave the required effects on the environment and the user to serve certain purpose or function. But it seems that the process of formulating any architectural vocabulary acting on the dynamic aspect goes beyond the boundaries of the perceived dimensions and the included unperceived one; as the first dimensions may be considered namely the aesthetic aspect in architectural work, while the included unperceived dimensions may display efficiency in work which is greatly influenced by the personality and the formative attitudes of the architect, the site style and the surrounded environment, as well as the economic efficiency of the building. However, the liability issue seems to be the absence of the criterion of forming efficient dynamic configurations in architecture. Accordingly this research aims to reach this criterion as identifying the architectural attitudes; as a decisive in shaping the building as its facades, envelopes, sections or plans. Additionally, it attempts to explain the reciprocal relation between the architectural vocabulary (perceived aspects of configuration) and the unperceived one which is distinguishing the valuable architectural works. The research will attempt to analyze the elements included and the aesthetic and formative considerations while configuring the dynamic building to determine the important role played by such formation in reaching the psychological and physiological effect on the user in turn to maximize its utilization of such architectural work

Tracing Analytic Ray Curves for Light and Sound Propagation in Non-Linear Media

The physical world consists of spatially varying media, such as the atmosphere and the ocean, in which light and sound propagates along non-linear trajectories. This presents a challenge to existing ray-tracing based methods, which are widely adopted to simulate propagation due to their efficiency and flexibility, but assume linear rays. We present a novel algorithm that traces analytic ray curves computed from local media gradients, and utilizes the closed-form solutions of both the intersections of the ray curves with planar surfaces, and the travel distance. By constructing an adaptive unstructured mesh, our algorithm is able to model general media profiles that vary in three dimensions with complex boundaries consisting of terrains and other scene objects such as buildings. Our analytic ray curve tracer with the adaptive mesh improves the efficiency considerably over prior methods. We highlight the algorithm's application on simulation of visual and sound propagation in outdoor scenes

Methods to get more information from sparse vessel monitoring systems data

Vessel Monitoring Systems (VMS) and other vessel tracking data have been used for many years to map the distribution of fishing activities. Mapping areas with low levels of fishing activity can be of particular interest; for example to avoid conflicts between fishing and other ocean uses like offshore renewable energy or to protect relatively pristine ecosystems from increasing fishing pressure. A particular problem when trying to delineate areas that are lightly fished, is the relative sparsity of vessel monitoring data in these areas. This paper explores three novel methods for estimating the distribution of fishing activity from VMS data, with particular focus on lightly impacted areas. The first new method divides the area of interest into a nested grid with varying cell sizes (depending on the density of data at each location); the second new method uses Voronoi diagrams to define polygons around observations and the third method applies a local regression to generate a smooth map of fishing intensity. The new methods are compared with two established methods: applying spatial grids and interpolating fishing tracks. The track interpolation method generally performs better than any of the new methods, however it is not always possible or appropriate to apply track interpolation; in those cases the local regression method is the best alternative

Volumetric-mapping-based inverse design of 3D architected materials and mobility control by topology reconstruction

The recent development of modular origami structures has ushered in a new era for active metamaterials with multiple degrees of freedom (multi-DOF). Notably, no systematic inverse design approach for volumetric modular origami structures has been reported. Moreover, very few topologies of modular origami have been studied for the design of active metamaterials with multi-DOF. Herein, we develop an inverse design method and reconfigurable algorithm for constructing 3D active architected structures - we synthesize modular origami structures that can be volumetrically mapped to a target 3D shape. We can control the reconfigurability by reconstructing the topology of the architected structures. Our inverse design based on volumetric mapping with mobility control by topology reconstruction can be used to construct architected metamaterials with any 3D complex shape that are also transformable with multi-DOF. Our work opens a new path toward 3D reconfigurable structures based on volumetric inverse design. This work is significant for the design of 3D active metamaterials and 3D morphing devices for automotive, aerospace, and biomedical engineering applications.Comment: 36 page