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arXiv 2024年

作者： Krishnamurthy, Vinayak Akleman, Ergun Mechanical Engineering Texas A&M University College StationTX77831 United States Visual Computing & Computational Media Texas A&M University College StationTX77831 United States

We present medial parametrization, a new approach to parameterize any compact planar domain bounded by a set of simple closed curves. The basic premise behind our proposed approach is to use two close Voronoi sites, which we call dipoles, to simultaneously construct and reconstruct an approximate piecewise-linear version of the original boundary and medial axis through Voronoi tessellation. The boundaries and medial axes of such planar compact domains, in conjunction with, offer a natural way to describe the interior of the domain. In fact, any compact planar domain homeomorphic to a compact unit circular disk admits a parameterization isomorphic to the (r, θ) or polar parametrization of the disk. Specifically, the medial axis and the boundary generalize the radial (r) and angular (θ) parameters, respectively. In this paper, we present a simple algorithm that puts these principles into practice. The algorithm is based on the simultaneous re-creation of the boundaries of the domain and its medial axis using Voronoi tessellation. This simultaneous re-creation provides partitions of the domain into a set of "skinny" convex polygons wherein each polygon is essentially a subset of the medial edges (which we call the spine) connected to the boundary through exactly two straight edges (which we call limbs). It is this unique structure that enables us to convert the original Voronoi tessellation into quadrilaterals and triangles (at the poles of the medial axis) neatly ordered along the boundaries of the domain, thereby allowing proper parametrization of the domain. Our approach is agnostic to the number of holes and disconnected components bounding the domain. We investigate the efficacy of our concept and algorithm through several examples. © 2024, CC BY.

关键词： Piecewise linear techniques

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ON THE POWER OF SUBTLE EXPRESSIVE CUES IN THE PERCEPTION OF HUMAN AFFECTS

arXiv

引用

arXiv 2024年

作者： Dede, Ezgi Agilonu, Kamile Asli Akleman, Ergun Sezgin, Metin College of Engineering Koc University Istanbul Turkey Visual Computing & Computational Media School of PVFA Computer Science and Engineering College of Engineering Texas A&M University College StationTX77831 United States

In this study, we introduce a sketch-based method for testing how subtle expressive cues influence the perception of affect in illustrations of human figures. We specifically study the impact of human posture and gaze direction, implicitly specified through nose orientation, on perceived emotions and mood. Through a series of user studies using sketchy illustrations of a running figure, where a professional illustrator manipulated gaze direction through adjustments on the nose orientation, we found that this simple change resulted in a diverse range of perceived affects, spanning from fear to concern and wonder. These findings shed light on the importance of fine details in defining context for context-aware system designs and underscore the importance of recognizing and expressing affect. Understanding minor expressive cues is crucial to developing emotionally intelligent systems capable of expressing affect. © 2024, CC BY.

关键词： Intelligent systems

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A DIGITAL COMPOSITING APPROACH TO OBTAIN ANIMATED CHINESE STILL-LIFE PAINTINGS WITH GLOBAL EFFECTS

arXiv

引用

arXiv 2023年

作者： Deng, Sitong Akleman, Ergun Department of Visualization Texas A&M University College StationTX77831 United States Visual Computing & Computational Media Texas A&M University College StationTX77831 United States

In this work, we present a method for turning Chinese still-life paintings with global illumination effects into dynamic paintings with moving lights. Our goal is to preserve the original look and feel of still-life paintings with moving lights and objects. We have developed a deceptively simple method that can be computed as a composite of two animated texture images using an animated rendering. The compositing process can be implemented directly in an animation system such as AfterEffect, which allows for the basic compositing operation over animations. It is also possible to control the colors by changing the material colors in animated rendering. We have provided a proof-of-concept based on an original digital Still-Life painting that is in realist Chinese style. This approach can be used to turn almost any still-life painting into a dynamic painting. © 2023, CC BY.

关键词： Textures

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RECURSIVE CAMERA PAINTING: A METHOD FOR REAL-TIME PAINTERLY RENDERINGS OF 3D SCENES

arXiv

引用

arXiv 2023年

作者： Akleman, Ergun Mullins, Cassie Morrison, Christopher Oh, David Visual Computing & Computational Media Texas A&M University College StationTX77831 United States Department of Visualization Texas A&M University College StationTX77831 United States

In this work, we present the recursive camera-painting approach to obtain painterly smudging in real-time rendering applications. We have implemented recursive camera painting as both a GPU-based ray-tracing and in a Virtual Reality game environment. Using this approach, we can obtain dynamic 3D Paintings in real-time. In a camera painting, each pixel has a separate associated camera whose parameters are computed from a corresponding image of the same size. In recursive camera painting, we use the rendered images to compute new camera parameters. When we apply this process a few times, it creates painterly images that can be viewed as real-time 3D dynamic paintings. These visual results are not surprising since multi-view techniques help to obtain painterly effects. © 2023, CC BY.

关键词： Cameras

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MULTI-AXIS AND MULTI-VECTOR GRADIENT ESTIMATIONS: USING MULTI-SAMPLED COMPLEX UNIT VECTORS TO ESTIMATE GRADIENTS OF REAL FUNCTIONS

arXiv

引用

arXiv 2023年

作者： Akleman, Ergun Freed, Alan D. Visual Computing & Computational Media Texas A&M University College StationTX77831 United States Department of Mechanical Engineering Texas A&M University College StationTX77831 United States

In this preliminary study, we provide two methods for estimating the gradients of functions of real value. Both methods are built on derivative estimations that are calculated using the standard method or the Squire-Trapp method Squire and Trapp [1998] for any given direction. Gradients are computed as the average of derivatives in uniformly sampled directions. The first method uses a uniformly distributed set of axes that consists of orthogonal unit vectors that span the space. The second method only uses a uniformly distributed set of unit vectors. Both methods essentially minimize the error through an average of estimations to cancel error terms. Both methods are essentially a conceptual generalization of the method used to estimate normal fractal surfaces Hart et al. [1989]. © 2023, CC BY.

关键词： Vectors

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Conformal Interpolations of Locally Defined Rotation, Scaling, and Translation Operations

Conformal Interpolations of Locally Defined Rotation, Scalin...

引用

IEEE Signal Processing and Communications Applications (SIU)

作者： Ergun Akleman Bekir Tevfik Akgün Visual Computing and Computational Media SVPA Texas A&M University Computer Science and Engineering College of Engineering Texas A&M University Bilgisayar ve Bilişim Bilimleri Fakültesi Yeditepe Üniversitesi

In image morphing applications, deformation is not desired since it looks strange. To avoid deformation, the angles must be locally preserved. By deforming features, we can obtain funny-looking images, however, the shapes of the features will not look preserved if angles are not preserved. The angle-preserving operations are called conformal maps and locally they expect to be reduced into a concatenation of rotation, uniform scaling, and translation operations. This conceptual framework appears to give us a straightforward framework to construct general conformal maps. We can simply define desired rotation, uniform scaling, and translation in some select points and interpolate them by preserving their conformal property. Unfortunately, this does not work if these local operations are defined by using 3x3 matrices. Our approach is based on the well-known conformal property of maps in complex domains. Namely, any map in a complex domain is angle-preserving. Based on this well-known property of complex numbers, we show that if the local operations are defined as affine operations on complex numbers then any interpolation on complex numbers will give us conformal mapping of the whole domain. This is very useful since we can make extreme exaggeration of some local features and the resulting maps are still guaranteed to be conformal. Using this property, we have implemented an extended and conformal version of feature-based image metamorphosis.

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MOMENTS FOR PERCEPTIVE NARRATION ANALYSIS THROUGH THE AUDIENCE’S EMOTIONAL ATTACHMENT TO DISCOURSE AND STORY

arXiv

引用

arXiv 2023年

作者： Bruins, Gary Akleman, Ergun School of Performance Visualization and Fine Arts Texas A&M University College StationTX77831 United States Visual Computing & Computational Media Texas A&M University College StationTX77831 United States

In this work, our goal is to develop a theoretical framework that can eventually be used for analyzing the effectiveness of visual stories such as feature films to comic books. To develop this theoretical framework, we introduce a new story element called moments. Our conjecture is that any linear story such as the story of a feature film can be decomposed into a set of moments that follow each other. Moments are defined as the perception of the actions, interactions, and expressions of all characters or a single character during a given time period. We categorize the moments into two major types: "story moments" and "discourse moments." Each type of moment can further be classified into three types, which we call universal storytelling moments. We believe these universal moments foster or deteriorate the audience’s emotional attachment to a particular character or the story. We present a methodology to catalog the occurrences of these universal moments as they are found in the story. The cataloged moments can be represented using curves or color strips. Therefore, we can visualize a character’s journey through the story as either a 3D curve or a color strip. We also demonstrated that both story and discourse moments can be transformed into one lump-sum "attraction" parameter. The attraction parameter in time provides a function that can be plotted graphically onto a timeline illustrating changes in the audience’s emotional attachment to a character or the story. By inspecting these functions the story analyst can analytically decipher the moments in the story where the attachment is being established, maintained, strengthened, or conversely where it is languishing. © 2023, CC BY.

关键词： Motion pictures

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DEVELOPMENT OF CONTEXT-SENSITIVE FORMULAS TO OBTAIN CONSTANT LUMINANCE PERCEPTION FOR A FOREGROUND OBJECT IN FRONT OF BACKGROUNDS OF VARYING LUMINANCE

arXiv

引用

arXiv 2024年

作者： Akleman, Ergun Akgun, Bekir Tevfik Alpkocak, Adil Visual Computing & Computational Media SPVFA Computer Science and Engineering COE Texas A&M University College StationTX77831 United States Faculty of Computer and Information Sciences Yeditepe University Istanbul Turkey Department of Computer Engineering Izmir Bakırçay University Menemen Turkey

In this article, we present a framework for developing context-sensitive luminance correction formulas that can produce constant luminance perception for foreground objects. Our formulas make the foreground object slightly translucent to mix with the blurred version of the background. This mix can be used to quickly produce any desired illusion of luminance in foreground objects based on the luminance of the background. The translucency formula has only one parameter;the relative size of the foreground object, which is a number between 0 and 1. We have identified the general structure of the translucency formulas as a power function of the form y = sf(s) where s ∈ [0, 1] is the relative size of the foreground object, f(s) is a polynomial, and y is the opacity of the foreground object. We have implemented a web-based interactive program in Shadertoy. Using this program, we determined the coefficients of the polynomials f(s). To intuitively control the coefficients of the polynomial functions, we have used a Bézier form. Our final translucency formula uses a quadratic polynomial and requires only three coefficients. We also identified a simpler affine formula, which requires only two coefficients. We made our program publicly available in Shadertoy so that anyone can access and improve it. In this article, we also explain how to intuitively change the polynomial part of the formula. Using our explanation, users change the polynomial part of the formula to obtain their own perceptively constant luminance. This can be used as a crowd-sourcing experiment for further improvement of the formula. © 2024, CC BY.

关键词： Luminance

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COMPOSITING WITH 2D VECTOR FIELDS BY USING SHAPE MAPS THAT CAN REPRESENT INCONSISTENT, IMPOSSIBLE, AND INCOHERENT SHAPES

arXiv

引用

arXiv 2024年

作者： Akleman, Ergun Wang, Youyou Gonen, Ozgur Visual Computing & Computational Media Texas A&M University College StationTX77831 United States Department of Computer Science and Engineering Texas A&M University College StationTX77831 United States Department of Architecture Texas A&M University College StationTX77831 United States

In this paper, we present a new compositing approach to obtain stylized reflections and refractions with a simple control. Our approach does not require any mask or separate 3D rendering. Moreover, only one additional image is sufficient to obtain a composited image with convincing qualitative reflection and refraction effects. We have also developed linearized methods that are easy to compute. Although these methods do not directly correspond to the underlying physical phenomena of reflection and refraction, they can provide results that are visually similar to realistic 3D rendering. The main advantage of this approach is the ability to treat images as "mock-3D" shapes that can be inserted into any digital paint system without any significant structural change. The core of our approach is the shape map, which encodes 2D shape and thickness information for all visible points of an image of a shape. This information does not have to be complete or consistent to obtain interesting composites. In particular, the shape maps allow us to represent impossible and incoherent shapes with 2D non-conservative vector fields. © 2024, CC BY.

关键词： Rendering (computer graphics)

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A MODIFIED DE CASTELJAU SUBDIVISION THAT SUPPORTS SMOOTH STITCHING WITH HIERARCHICALLY ORGANIZED BICUBIC BÉZIER PATCHES

arXiv

引用

arXiv 2024年

作者： Zarrinmehr, Saied Akleman, Ergun Chen, Jianer Computer Science and Engineering Department Texas A&M University College StationTX77831 United States Visual Computing & Computational Media Texas A&M University College StationTX77831 United States Computer Science and Engineering College of Engineering Texas A&M University College StationTX77831 United States

One of the theoretically intriguing problems in computer-aided geometric modeling comes from the stitching of the tensor product Bézier patches. When they share an extraordinary vertex, it is not possible to obtain continuity C1 or G1 along the edges emanating from that extraordinary vertex. Unfortunately, this stitching problem cannot be solved by using higher degree or rational polynomials. In this paper, we present a modified de Casteljau subdivision algorithm that can provide a solution to this problem. The main advantage of the modified subdivision is that the continuity C1 on a given boundary edge does not depend on the positions of the control points on other boundary edges. The modified subdivision allows us to obtain the desired C1 continuity along the edges emanating from the extraordinary vertices along with the desired G1 continuity in the extraordinary vertices (see Figures 2 and 3). Our modified de Casteljau subdivision, when combined with topological modeling, provides a framework for interactive real-time modeling of piecewise smooth manifold meshes with arbitrary topology. Based on this approach, we have extended an interactive modeling system to topologically update a smooth surface in real-time by opening or closing holes, creating handles, and combining and disconnecting surfaces (see Figure 1 for an example). The smooth surfaces resulting from any given orientable two-manifold polynomial mesh have the following properties: (1) These surfaces consist of hierarchically organized C2 continuous bicubic Bézier patches. (2) They provide visual smoothness by providing geometric G1 continuity in the extraordinary vertices and C1 continuity along the edges emanating from the extraordinary vertices. (3) They can be updated interactively in real time by directly evaluating the underlying Bézier patches. © 2024, CC BY.

关键词： Topology

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