A comparative study of interactive segmentation with different number of strokes on complex images

Interactive image segmentation is the way to extract an object of interest with the guidance of the user. The guidance from the user is an iterative process until the required object of interest had been segmented. Therefore, the input from the user as well as the understanding of the algorithms based on the user input has an essential role in the success of interactive segmentation. The most common user input type in interactive segmentation is using strokes. The different number of strokes are utilized in each different interactive segmentation algorithms. There was no evaluation of the effects on the number of strokes on this interactive segmentation. Therefore, this paper intends to fill this shortcoming. In this study, the input strokes had been categorized into single, double, and multiple strokes. The use of the same number of strokes on the object of interest and background on three interactive segmentation algorithms: i) Nonparametric Higher-order Learning (NHL), ii) Maximal Similarity-based Region Merging (MSRM) and iii) Graph-Based Manifold Ranking (GBMR) are evaluated, focusing on the complex images from Berkeley image dataset. This dataset contains a total of 12,000 test color images and ground truth images. Two types of complex images had been selected for the experiment: image with a background color like the object of interest, and image with the object of interest overlapped with other similar objects. This can be concluded that, generally, more strokes used as input could improve image segmentation accuracy

Fantastic Breaks: A Dataset of Paired 3D Scans of Real-World Broken Objects and Their Complete Counterparts

Automated shape repair approaches currently lack access to datasets that describe real-world damaged geometry. We present Fantastic Breaks (and Where to Find Them: https://terascale-all-sensing-research-studio.github.io/FantasticBreaks), a dataset containing scanned, waterproofed, and cleaned 3D meshes for 150 broken objects, paired and geometrically aligned with complete counterparts. Fantastic Breaks contains class and material labels, proxy repair parts that join to broken meshes to generate complete meshes, and manually annotated fracture boundaries. Through a detailed analysis of fracture geometry, we reveal differences between Fantastic Breaks and synthetic fracture datasets generated using geometric and physics-based methods. We show experimental shape repair evaluation with Fantastic Breaks using multiple learning-based approaches pre-trained with synthetic datasets and re-trained with subset of Fantastic Breaks.Comment: To be published at CVPR 202

Master of Science

thesisDue to the complex failure modes associated with composites, a structural health monitoring system capable of accurately locating the source of strength-reducing events is desirable in order to reduce inspection time and time out of service. Various active and passive inspection techniques exist but most require large footprints and extensive cabling to monitor full scale structures. This work derives various location techniques by coupling modal acoustic emissions with phased array techniques to detect and accurately locate the source of strength-reducing events such as impacts. Phased array techniques provide a method to more accurately track phase points for determining arrival times used to back-calculate the source, as well as providing a method that can incorporate anisotropic wave speeds. To increase accuracy by neglecting local to global material changes, the local velocity profile per component was found and built into the derived location algorithms. The location algorithms were then tested on two full scale composite structures based on strength and stiffness critical design considerations. It was found that with two arrays, each with dimensions of 1 inches in width and 8 inches in length and consisting of four sensors each, events could be accurately located over a 65 ft2 region on the stiffness critical structure with an average error of 10 inches and over a 100 ft2 region on the strength critical structure with an average error of 9 inches

Efficient data structures for piecewise-smooth video processing

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 95-102).A number of useful image and video processing techniques, ranging from low level operations such as denoising and detail enhancement to higher level methods such as object manipulation and special effects, rely on piecewise-smooth functions computed from the input data. In this thesis, we present two computationally efficient data structures for representing piecewise-smooth visual information and demonstrate how they can dramatically simplify and accelerate a variety of video processing algorithms. We start by introducing the bilateral grid, an image representation that explicitly accounts for intensity edges. By interpreting brightness values as Euclidean coordinates, the bilateral grid enables simple expressions for edge-aware filters. Smooth functions defined on the bilateral grid are piecewise-smooth in image space. Within this framework, we derive efficient reinterpretations of a number of edge-aware filters commonly used in computational photography as operations on the bilateral grid, including the bilateral filter, edgeaware scattered data interpolation, and local histogram equalization. We also show how these techniques can be easily parallelized onto modern graphics hardware for real-time processing of high definition video. The second data structure we introduce is the video mesh, designed as a flexible central data structure for general-purpose video editing. It represents objects in a video sequence as 2.5D "paper cutouts" and allows interactive editing of moving objects and modeling of depth, which enables 3D effects and post-exposure camera control. In our representation, we assume that motion and depth are piecewise-smooth, and encode them sparsely as a set of points tracked over time. The video mesh is a triangulation over this point set and per-pixel information is obtained by interpolation. To handle occlusions and detailed object boundaries, we rely on the user to rotoscope the scene at a sparse set of frames using spline curves. We introduce an algorithm to robustly and automatically cut the mesh into local layers with proper occlusion topology, and propagate the splines to the remaining frames. Object boundaries are refined with per-pixel alpha mattes. At its core, the video mesh is a collection of texture-mapped triangles, which we can edit and render interactively using graphics hardware. We demonstrate the effectiveness of our representation with special effects such as 3D viewpoint changes, object insertion, depthof- field manipulation, and 2D to 3D video conversion.by Jiawen Chen.Ph.D

Collected Papers in Structural Mechanics Honoring Dr. James H. Starnes, Jr.

This special publication contains a collection of structural mechanics papers honoring Dr. James H. Starnes, Jr. presented at the 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference held in Austin, Texas, April 18-21, 2005. Contributors to this publication represent a small number of those influenced by Dr. Starnes' technical leadership, his technical prowess and diversity, and his technical breath and depth in engineering mechanics. These papers cover some of the research areas Dr. Starnes investigated, which included buckling, postbuckling, and collapse of structures; composite structural mechanics, residual strength and damage tolerance of metallic and composite structures; and aircraft structural design, certification and verification. He actively pursued technical understanding and clarity, championed technical excellence, and modeled humility and perseverance

End Effector for Robotic Strawberry Picker Final Design Review

In this report, we have outlined the background of the problem and need for a solution to an automated form of strawberry harvesting. The report includes our research findings, defines the scope and objectives for this project, and documents our complete design process. Also included is our final, completed prototype, and a description of the manufacturing, design verification and testing process. Also included is our conclusions and recommendations for further improvement on future iterations

Tensile Mechanics of the Knee Meniscus in the Context of Cracks: Failure and Fracture Mechanisms, Strain Concentrations, and the Effect of Specimen Shape

Knee meniscus tears (cracks) are a major cause of knee dysfunction and osteoarthritis, but little is known about how they grow or what effects they have on meniscus mechanics. The objective of this work was to investigate the mechanics and failure of crack-free and cracked meniscus in uniaxial tension, with specific attention to failure mechanisms (fracture and bulk rupture) and local strain concentrations. A finite element model was used to find a test configuration likely to cause fracture and crack propagation. Center cracks with a 45° crack–fiber angle were selected for producing large fiber stresses, and 90° edge cracks were selected for producing large inter-fiber shear stresses. The circumferential and radial tensile mechanics of the meniscus were quantified using ex vivo tensile testing. A fiber recruitment model was fitted to the test data, and a method was developed to quantify the inflection (yield) point and modulus based on the shape of the stress–strain curve. Comparison of tensile test specimen shapes showed that an expanded tab specimen shape produces more rapid and complete fiber recruitment, lesser yield strain, and greater peak stress (strength) than rectangle specimens, and, likely, dogbone specimens. Mechanical effects of meniscus cracks were quantified by comparing cracked and crack-free specimens in circumferential and radial tension. The cracks did not cause a decrease in peak stress, indicating fracture did not occur. However, significantly greater longitudinal strain and shear strain was found near the crack tip for circumferential tension specimens. In radial tension specimens, all strain field components were greater near the crack tip. Failure tended to proceed along fascicle boundaries. Circumferential specimens failed by widespread interdigitating fiber pull-out, which also caused crack deflection. Radial specimens failed by necking and fiber rotation. These data demonstrate the remarkable fracture toughness of the meniscus, but increased near-tip strain may cause sub-failure damage and dysfunction. These results provide functional targets for interventions to repair or regenerate the meniscus

Stability Analysis of Plates and Shells

This special publication contains the papers presented at the special sessions honoring Dr. Manuel Stein during the 38th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference held in Kissimmee, Florida, Apdl 7-10, 1997. This volume, and the SDM special sessions, are dedicated to the memory of Dr. Manuel Stein, a major pioneer in structural mechanics, plate and shell buckling, and composite structures. Many of the papers presented are the work of Manny's colleagues and co-workers and are a result, directly or indirectly, of his influence. Dr. Stein earned his Ph.D. in Engineering Mechanics from Virginia Polytechnic Institute and State University in 1958. He worked in the Structural Mechanics Branch at the NASA Langley Research Center from 1943 until 1989. Following his retirement, Dr. Stein continued his involvement with NASA as a Distinguished Research Associate