Littérature scientifique sur le sujet « Stroke-based rendering »

Vector graphics includes both filled and stroked paths as the main primitives. While there are many techniques for rendering filled paths on GPU, stroked paths have proved more elusive. This paper presents a technique for performing stroke expansion, namely the generation of the outline representing the stroke of the given input path. Stroke expansion is a global problem, with challenging constraints on continuity and correctness. Nonetheless, we implement it using a fully parallel algorithm suitable for execution in a GPU compute shader, with minimal preprocessing. The output of our method can be either line or circular arc segments, both of which are well suited to GPU rendering, and the number of segments is minimal. We introduce several novel techniques, including an encoding of vector graphics primitives suitable for parallel processing, and an Euler spiral based method for computing approximations to parallel curves and evolutes.

The automatic style translation of Chinese characters (CH-Char) is a challenging problem. Different from English or general artistic style transfer, Chinese characters contain a large number of glyphs with the complicated content and characteristic style. Early methods on CH-Char synthesis are inefficient and require manual intervention. Recently some GAN-based methods are proposed for font generation. The supervised GAN-based methods require numerous image pairs, which is difficult for many chirography styles. In addition, unsupervised methods often cause the blurred and incorrect strokes. Therefore, in this work, we propose a three-stage Generative Adversarial Network (GAN) architecture for multi-chirography image translation, which is divided into skeleton extraction, skeleton transformation and stroke rendering with unpaired training data. Specifically, we first propose a fast skeleton extraction method (ENet). Secondly, we utilize the extracted skeleton and the original image to train a GAN model, RNet (a stroke rendering network), to learn how to render the skeleton with stroke details in target style. Finally, the pre-trained model RNet is employed to assist another GAN model, TNet (a skeleton transformation network), to learn to transform the skeleton structure on the unlabeled skeleton set. We demonstrate the validity of our method on two chirography datasets we established.

We present a new non-photorealistic rendering (NPR) algorithm for rendering photographs in an impasto painterly style. We observe that most existing image-based NPR algorithms operate in a spatially local manner, typically as non-linear image filters seeking to preserve edges and other high-frequency content. By contrast, we argue that figurative artworks are salience maps, and develop a novel painting algorithm that uses a genetic algorithm (GA) to search the space of possible paintings for a given image, so approaching an "optimal" artwork in which salient detail is conserved and non-salient detail is attenuated. Differential rendering styles are also possible by varying stroke style according to the classification of salient artifacts encountered, for example edges or ridges. We demonstrate the results of our technique on a wide range of images, illustrating both the improved control over level of detail due to our salience adaptive painting approach, and the benefits gained by subsequent relaxation of the painting using the GA.

<span lang="EN-US"><span>The present study aimed to investigate the metacognitive ability of students using e-portfolio assessment in project-based learning classes. The projects were a set out a critical analysis based on the selected references (project 1) and set out of field activities based on the selected theme content (project 2). Student metacognitive ability consists of three phases, planning, implementation, and evaluation abilities that were assessed through e-portfolio assignments. There were 87 participants who divided into groups consisted of four to five students, conducted the projects, and submitted the progress of their projects in every decided step into online report assignments. The rubric of metacognition was used to acquire the quantitative score of skill that was separated into six levels category: not yet, at risk, not-really, developing, OK, and super. The result revealed that 44.83% of the students belong to the last three of those levels and the rest are otherwise. The lowest and highest metacognitive ability of the student is “not really” and “developing” respectively. Student metacognitive ability through conducting the project 2 activities is higher than project 1. The findings showed that project-based learning (PBL) enables to foster the student metacognitive ability that developed through e-portfolio-based documents that student conducted during fulfilling all projects assignments.</span>The aim of present study was to investigate the metacognitive ability of student using e-portfolio assessment in the project-based learning classes. The projects were the set out a critical analysis based on the selected references (project 1) and the set out of field activities based on the selected theme content (project 2). Student metacognitive ability consists of three phases, planning, implementation and evaluation abilities that were assessed through e-portfolio assignments. Eighty-seven participants divided into groups consisted of four to five students, conducted the projects, and submitted the progress of their projects in every decided step into online report assignments. The rubric of metacognition was used to acquire the quantitative score of skill that was separated into six levels category; not yet, at risk, not really, developing, OK, and super. The result revealed that 44.83% of the students belong to the last three of those levels and the rest are otherwise. The lowest and highest metacognitive ability of student is "not really" and "developing” respectively. Student metacognitive ability through conducting the project 2 activities is higher than the project 1. The findings showed that PjBl enable to foster the student metacognitive ability that developed through e-portfolio-based documents that student conducted during fulfilling all projects assignments.</span><div class="ms-editor-squiggler" style="color: initial; font: initial; font-feature-settings: initial; font-kerning: initial; font-optical-sizing: initial; font-variation-settings: initial; forced-color-adjust: initial; text-orientation: initial; text-rendering: initial; -webkit-font-smoothing: initial; -webkit-locale: initial; -webkit-text-orientation: initial; -webkit-writing-mode: initial; writing-mode: initial; zoom: initial; place-content: initial; place-items: initial; place-self: initial; alignment-baseline: initial; animation: initial; appearance: initial; aspect-ratio: initial; backdrop-filter: initial; backface-visibility: initial; background: initial; background-blend-mode: initial; baseline-shift: initial; block-size: initial; border-block: initial; border: initial; border-radius: initial; 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x: initial; y: initial; z-index: initial;"> </div><div class="ms-editor-squiggler" style="color: initial; font: initial; font-feature-settings: initial; font-kerning: initial; font-optical-sizing: initial; font-variation-settings: initial; forced-color-adjust: initial; text-orientation: initial; text-rendering: initial; -webkit-font-smoothing: initial; -webkit-locale: initial; -webkit-text-orientation: initial; -webkit-writing-mode: initial; writing-mode: initial; zoom: initial; place-content: initial; place-items: initial; place-self: initial; alignment-baseline: initial; animation: initial; appearance: initial; aspect-ratio: initial; backdrop-filter: initial; backface-visibility: initial; background: initial; background-blend-mode: initial; baseline-shift: initial; block-size: initial; border-block: initial; border: initial; border-radius: initial; border-collapse: initial; border-end-end-radius: initial; border-end-start-radius: initial; border-inline: initial; border-start-end-radius: initial; 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padding: initial; padding-inline: initial; page: initial; page-orientation: initial; paint-order: initial; perspective: initial; perspective-origin: initial; pointer-events: initial; position: initial; quotes: initial; r: initial; resize: initial; ruby-position: initial; rx: initial; ry: initial; scroll-behavior: initial; scroll-margin-block: initial; scroll-margin: initial; scroll-margin-inline: initial; scroll-padding-block: initial; scroll-padding: initial; scroll-padding-inline: initial; scroll-snap-align: initial; scroll-snap-stop: initial; scroll-snap-type: initial; shape-image-threshold: initial; shape-margin: initial; shape-outside: initial; shape-rendering: initial; size: initial; speak: initial; stop-color: initial; stop-opacity: initial; stroke: initial; stroke-dasharray: initial; stroke-dashoffset: initial; stroke-linecap: initial; stroke-linejoin: initial; stroke-miterlimit: initial; stroke-opacity: initial; stroke-width: initial; tab-size: initial; table-layout: initial; 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-webkit-line-clamp: initial; -webkit-mask-box-image: initial; -webkit-mask: initial; -webkit-mask-composite: initial; -webkit-perspective-origin-x: initial; -webkit-perspective-origin-y: initial; -webkit-print-color-adjust: initial; -webkit-rtl-ordering: initial; -webkit-ruby-position: initial; -webkit-tap-highlight-color: initial; -webkit-text-combine: initial; -webkit-text-decorations-in-effect: initial; -webkit-text-emphasis: initial; -webkit-text-emphasis-position: initial; -webkit-text-fill-color: initial; -webkit-text-security: initial; -webkit-text-stroke: initial; -webkit-transform-origin-x: initial; -webkit-transform-origin-y: initial; -webkit-transform-origin-z: initial; -webkit-user-drag: initial; -webkit-user-modify: initial; white-space: initial; widows: initial; width: initial; will-change: initial; word-break: initial; word-spacing: initial; x: initial; y: initial; z-index: initial;"> </div>

Dans le cadre de ma thèse, je m'intéresse à la problématique de la création d'animations 2D traditionnelles, où toutes les images sont réalisées à la main. Je cherche à explorer comment l'ordinateur peut aider les artistes à produire de manière plus efficace sans pour autant empiéter sur le spectre de la création artistique. Pour répondre à ce problème, mes travaux se placent dans le domaine des méthodes automatiques, où l'animateur travaille de manière itérative avec l'ordinateur. Je propose une méthode qui, à partir de deux images clés et d'une série de champs vectoriels 2D décrivant le mouvement dans l'espace image de l'animation, génère des images intermédiaires et reproduit le style donné en exemple. Ma méthode se situe à l'intersection de deux techniques manuelles d'animation : l'animation pose à pose et l'animation sous la caméra, et assure un contrôle fort en permettant d'éditer n'importe quelle image générée de la même manière que celles données en exemple. Mes travaux englobent plusieurs domaines, notamment l'analyse du mouvement, le contrôle de courbe 2D, le rendu à base de marques et la simulation de la peinture
As part of my thesis, I am interested in the issue of creating traditional 2D animations, where all the images are handcrafted. Specifically, I explore how computers can assist artists in producing animations efficiently without reducing the artistic creative process. To address this problem, my work falls within the scope of automatic methods, where the animator collaborates iteratively with the computer. I propose a method that takes two keyframe images and a series of 2D vector fields describing the motion in image space of the animation, and generates intermediate images while preserving the given style as an example. My method combines two manual animation techniques: pose-to-pose and frame-by-frame animation, providing strong control by allowing any generated image to be edited in the same way as the example images provided. My research covers several domains: motion analysis, 2D curve control, mark-based rendering, and paint simulation

eXpressive B-Spline Curve (XBSC) is a resolution-independent and computationally efficient technique for vector-based stroke modeling and rendering with the flexibility in defining and adjusting the shape and other parameters of the stroke. It generalizes the existing Disk B-Spline Curve (DBSC) geometric representation, which itself is a generalization of the Disk Bézier curve. XBSC allows flexible shape and color manipulation and rendering of strokes with asymmetrical shape control and rich color management. These properties make XBSC suitable for modeling freeform stroke shapes and animation, specifically in squash and stretch, a common technique to bestow elasticity and flexibility in shape changes. During the squash and stretch animation computation, we constrain the shape of the XBSC stroke to conserve its area. To achieve this, we apply the simulated annealing algorithm to iteratively adjust the XBSC while maintaining its area. We show several drawings, rendering and deformation examples to demonstrate the robustness of XBSC.

Homogeneous-charge, compression-ignition (HCCI) combustion is triggered by spontaneous ignition in diluted homogeneous mixtures and has a gradual trend thanks to suitable solutions. It is considered a very effective way to reduce engine pollutant emissions, however only experimental prototypes have been based on this concept, except for a few small two-stroke engines. HCCI combustion is feasible with fuels both for S.I. and for C.I. engines, but currently it does not cover the whole engine operating field, thus the engine must be built to operate also as a conventional engine. In order to obtain a gradual combustion and not a simultaneous reaction (as it would be in spontaneously ignited homogeneous mixture), lean mixture is used and appropriate solutions, as Exhaust Gas Recirculation (EGR), are necessary. However, the admission of exhaust gas into the cylinder goes to detriment of engine maximum mean effective pressure. This paper concerns a preliminary study of an innovative concept to control HCCI combustion in Diesel-fuelled engines, apart from exhaust gas presence, the function of which is limited to NOx emission control. The main purpose of the research is the obtaining of Diesel HCCI combustion also with high mean effective pressures rendering the combustion behaviour more controllable as well. The concept consists in forming a pre-compressed homogenous charge outside the cylinder and in gradually admitting it into the cylinder during the combustion process. In this way, combustion can be controlled by the flow rate transfer and high pressure gradients, typical of common HCCI combustion, can be limited as well. A first analysis has been done, considering a cylinder filled with a perfectly stirred mixture of air and diesel fuel through a transfer duct, only to test the validity of the concept, regardless of which effective solution will be adopted. Both Two and Four Stroke operations have been considered to realize the concept. Results in terms of pressure, heat release rate, temperature and emission production have pointed out the validity of the concept. Especially the Two Stroke solution produces more soot than the conventional Diesel, pointing out that the air-fuel mixing is probably not optimized. Regarding NOx emissions, both the proposed solutions give better results than the conventional Diesel engine.

First principle Digital Twins (DT) for marine engines are widely used to estimate in-cylinder pressure, which is a key parameter informing health of ship power plants. However, development and application of DT faces barriers, as they require exhaustive calibration and high computational power, which render their implementation for shipboard systems challenging. This study aims at developing a data-driven DT of low computational cost for predicting instantaneous pressure. Two different approaches using Artificial Neural Networks (ANN) with distinct input parameters are assessed. The first predicts in-cylinder pressure as a function of the phase angle, whereas the second predicts the discrete Fourier coefficients (FC) corresponding to the in-cylinder pressure variations. The case study of a conventional medium speed four-stroke diesel marine engine is employed, for which the first principle DT based on a thermodynamic, zero dimensional approach was setup and calibrated against shop trials measurements. The DT is subsequently employed to generate data for training and validating developed ANNs. The derived results demonstrate that the second approach exhibits mean square errors within ±2% and requires the lowest computations cost, rendering it appropriate for marine engines DTs. Sensitivity analysis results verify the amount of training data and number of Fourier coefficients required to achieve adequate accuracy.