A Computational Model of the Short-Cut Rule for 2D Shape Decomposition

We propose a new 2D shape decomposition method based on the short-cut rule. The short-cut rule originates from cognition research, and states that the human visual system prefers to partition an object into parts using the shortest possible cuts. We propose and implement a computational model for the short-cut rule and apply it to the problem of shape decomposition. The model we proposed generates a set of cut hypotheses passing through the points on the silhouette which represent the negative minima of curvature. We then show that most part-cut hypotheses can be eliminated by analysis of local properties of each. Finally, the remaining hypotheses are evaluated in ascending length order, which guarantees that of any pair of conflicting cuts only the shortest will be accepted. We demonstrate that, compared with state-of-the-art shape decomposition methods, the proposed approach achieves decomposition results which better correspond to human intuition as revealed in psychological experiments.Comment: 11 page

Flexible Object Manipulation

Flexible objects are a challenge to manipulate. Their motions are hard to predict, and the high number of degrees of freedom makes sensing, control, and planning difficult. Additionally, they have more complex friction and contact issues than rigid bodies, and they may stretch and compress. In this thesis, I explore two major types of flexible materials: cloth and string. For rigid bodies, one of the most basic problems in manipulation is the development of immobilizing grasps. The same problem exists for flexible objects. I have shown that a simple polygonal piece of cloth can be fully immobilized by grasping all convex vertices and no more than one third of the concave vertices. I also explored simple manipulation methods that make use of gravity to reduce the number of fingers necessary for grasping. I have built a system for folding a T-shirt using a 4 DOF arm and a fixed-length iron bar which simulates two fingers. The main goal with string manipulation has been to tie knots without the use of any sensing. I have developed single-piece fixtures capable of tying knots in fishing line, solder, and wire, along with a more complex track-based system for autonomously tying a knot in steel wire. I have also developed a series of different fixtures that use compressed air to tie knots in string. Additionally, I have designed four-piece fixtures, which demonstrate a way to fully enclose a knot during the insertion process, while guaranteeing that extraction will always succeed

Image Collage on Arbitrary Shape via Shape-Aware Slicing and Optimization

Image collage is a very useful tool for visualizing an image collection. Most of the existing methods and commercial applications for generating image collages are designed on simple shapes, such as rectangular and circular layouts. This greatly limits the use of image collages in some artistic and creative settings. Although there are some methods that can generate irregularly-shaped image collages, they often suffer from severe image overlapping and excessive blank space. This prevents such methods from being effective information communication tools. In this paper, we present a shape slicing algorithm and an optimization scheme that can create image collages of arbitrary shapes in an informative and visually pleasing manner given an input shape and an image collection. To overcome the challenge of irregular shapes, we propose a novel algorithm, called Shape-Aware Slicing, which partitions the input shape into cells based on medial axis and binary slicing tree. Shape-Aware Slicing, which is designed specifically for irregular shapes, takes human perception and shape structure into account to generate visually pleasing partitions. Then, the layout is optimized by analyzing input images with the goal of maximizing the total salient regions of the images. To evaluate our method, we conduct extensive experiments and compare our results against previous work. The evaluations show that our proposed algorithm can efficiently arrange image collections on irregular shapes and create visually superior results than prior work and existing commercial tools.Comment: This paper has been accepted for publication on IEEE Transactions on Visualization and Computer Graphics (TVCG), March 2023. Project website http://graphics.csie.ncku.edu.tw/shapedimagecollag

Logic and phenomenology of incompleteness in illusory figures: new cases and hypotheses

Why is it relevant to analyze the role of incompleteness in illusory figure formation? Incompleteness probes the general problems of organization of the visual world and object segregation. The organization problem is one of the most important problems in visual neuroscience; namely: How and why are a very large numebr of unorganized elements of the retinal image combined, reduced, grouped and segregated to create visual objects? Within the problem of organizaiton, illusory figures are often considered to be one of the best examples to understand how and why the visual system segregates objects with a particular shape, color, and depth stratification. Understanding the role played by incompleteness in inducing illusory figures can thus be useful for understanding the principles of organization (the How) of perceptual forms and the more general logic of perception (the Why). To this purpose, incompletenss is here studied by analyzing its underlying organization principles and its inner logic

Towards recovery of complex shapes in meshes using digital images for reverse engineering applications

When an object owns complex shapes, or when its outer surfaces are simply inaccessible, some of its parts may not be captured during its reverse engineering. These deficiencies in the point cloud result in a set of holes in the reconstructed mesh. This paper deals with the use of information extracted from digital images to recover missing areas of a physical object. The proposed algorithm fills in these holes by solving an optimization problem that combines two kinds of information: (1) the geometric information available on the surrounding of the holes, (2) the information contained in an image of the real object. The constraints come from the image irradiance equation, a first-order non-linear partial differential equation that links the position of the mesh vertices to the light intensity of the image pixels. The blending conditions are satisfied by using an objective function based on a mechanical model of bar network that simulates the curvature evolution over the mesh. The inherent shortcomings both to the current holefilling algorithms and the resolution of the image irradiance equations are overcom

PREFERENCE OF CONSUMERS TOWARD NON-DISTORTED GRAPHICS ON FULL-BODY SHRINK SLEEVE LABELS

Past research has indicated that shrink sleeves can lead to higher product trial rates, better long-term sales, and greater likelihood of brand loyalty. A pilot study and a primary experiment were conducted to investigate the significance of distortion and the ability of the Human Visual System (HVS) to recognize it in packaging design. Distortion works primarily in shrink film on which an image is printed, so these studies dealt only with reductive distortion. The pilot study aimed to identify the absolute threshold, or Just-Noticeable-Difference (JND) for a change from no stimulus, for simple polygons. The primary experiment focused on graphic distortion in full body shrink sleeves (FBSS). Treatments presented each of the stimulus levels, along with a control for comparison, using a 2-AFC (Alternative Forced-Choice) Method. This study used a mixed 2 (labels) x 3 (bottles) x 5 (distortion increments) model, effectively 30 treatments in a Randomized Complete Block Design (RCBD). Label was a between-subject variable while Bottle Shape and Distortion Percentage were within-subject variables. Data indicated that distortion has a significant effect at 100%, but that there is not a threshold at which consumers are guaranteed to perceive graphic distortion on FBSS. Men detected distortion better than women. Participants who said distortion would prevent a purchase decision had the same tolerance as those who reported that it would not. Bottle shape may only impact consumer acceptance of distortion with some percentages of distortion. Familiarity with a brand name label may increase consumer tolerance and acceptance of distortion, and may do so more on some bottle shapes