A method for reconstructing sketched polyhedral shapes with rounds and fillets

In this paper we present a method for detecting rounds and fillets in engineering sketches and drawings, and automatically generating a 3D model of the corresponding object, with rounds and fillets applied. This method is useful both as a component of computer-aided sketching tools and in determining de- sign intent—although rounds and fillets are common in engineering parts, they often conceal design intent, which is more easily determined from the object’s underlying polyhedral skeleton

Paper and pen: A 3D sketching system

This paper proposes a method that resembles a natural pen and paper interface to create curve based 3D sketches. The system is particularly useful for representing initial 3D design ideas without much effort. Users interact with the system by the help of a pressure sensitive pen tablet. The input strokes of the users are projected onto a drawing plane, which serves as a paper that they can place anywhere in the 3D scene. The resulting 3D sketch is visualized emphasizing depth perception. Our evaluation involving several naive users suggest that the system is suitable for a broad range of users to easily express their ideas in 3D. We further analyze the system with the help of an architect to demonstrate the expressive capabilities. © 2013 Springer-Verlag London

Computer-Aided Patient-Specific Coronary Artery Graft Design Improvements Using CFD Coupled Shape Optimizer

This study aims to (i) demonstrate the efficacy of a new surgical planning framework for complex cardiovascular reconstructions, (ii) develop a computational fluid dynamics (CFD) coupled multi-dimensional shape optimization method to aid patient-specific coronary artery by-pass graft (CABG) design and, (iii) compare the hemodynamic efficiency of the sequential CABG, i.e., raising a daughter parallel branch from the parent CABG in patient-specific 3D settings. Hemodynamic efficiency of patient-specific complete revascularization scenarios for right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) bypasses were investigated in comparison to the stenosis condition. Multivariate 2D constraint optimization was applied on the left internal mammary artery (LIMA) graft, which was parameterized based on actual surgical settings extracted from 2D CT slices. The objective function was set to minimize the local variation of wall shear stress (WSS) and other hemodynamic indices (energy dissipation, flow deviation angle, average WSS, and vorticity) that correlate with performance of the graft and risk of re-stenosis at the anastomosis zone. Once the optimized 2D graft shape was obtained, it was translated to 3D using an in-house “sketch-based” interactive anatomical editing tool. The final graft design was evaluated using an experimentally validated second-order non-Newtonian CFD solver incorporating resistance based outlet boundary conditions. 3D patient-specific simulations for the healthy coronary anatomy produced realistic coronary flows. All revascularization techniques restored coronary perfusions to the healthy baseline. Multi-scale evaluation of the optimized LIMA graft enabled significant wall shear stress gradient (WSSG) relief (~34%). In comparison to original LIMA graft, sequential graft also lowered the WSSG by 15% proximal to LAD and diagonal bifurcation. The proposed sketch-based surgical planning paradigm evaluated the selected coronary bypass surgery procedures based on acute hemodynamic readjustments of aorta-CA flow. This methodology may provide a rational to aid surgical decision making in time-critical, patient-specific CA bypass operations before in vivo execution

An Intuitive Sketch-based Conceptual Design System Using a 3D Curve Network

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2014. 8. 이건우.전통적인 3차원 모델링 방식은 WIMP(Window, Icon, Menu, Pointer)의 패러다임으로 발전해 왔고, 최근에는 터치 입력장치 기술이 크게 발달하면서 스케치 기반의 3차원 모델링 방법의 연구가 활발히 진행되고 있다. 특히 사용자에게 종이와 펜을 이용해 그림을 그리는 듯한 환경을 제공하여 개념 스케치를 위한 3차원 곡선 생성 방법 또한 다양하게 연구되고 있다. 그러나 기존의 개념 스케치 용 디자인 시스템은 학습하는데 많은 시간이 걸릴 뿐만 아니라 3차원 원근 스케치에 익숙하지 않은 사람에게 사용이 어려운 단점이 있다. 이 논문에서는 시스템-사용자 간 인터랙션의 직관성을 높이고 다양한 형상의 개념 스케치가 이루어지도록 새로운 3차원 곡선 생성 방법을 제안한다. 이는 3차원 스케치에 필요한 최소한의 도구들을 사용하여 학습의 용이성을 높이고, 기존 곡선들과의 연관성을 이용해 3차원 곡선을 손쉽게 생성하도록 하여 사용자가 3차원 원근 스케치 환경에 쉽게 적응하도록 한다. 이러한 방법들을 통합적으로 구축하여 비숙련자 대상으로 사용자 평가를 실시하였고 새로운 시스템에 대한 좋은 유용성과 학습 용이성의 결과를 얻었다. 이 논문에서 제안하는 3차원 곡선 생성 방법들은 아이디어 스케치나 다양한 개념 디자인 용 모델을 스케치 할 수 있다는 점에서 큰 의의를 갖는다. 더 나아가 제품 디자인 용 스케치와 더불어 CAD 모델로도 재구성이 가능한 통합적인 모델링 시스템으로도 사용될 수 있을 것으로 기대한다.제 1 장 서론 1 제 2 장 시스템 구조 5 2.1 곡선 네트워크 생성 과정 6 2.2 사용자 인터페이스 구현 7 2.3 모델링 저작/편집 도구 8 제 3 장 곡선 네트워크 생성 10 3.1 스케치 평면 설정 10 3.2 2차원 스케치 생성 11 3.3 3차원 스케치 생성 12 3.3.1 3차원 직접 스케치 12 3.3.2 단계별 3차원 곡선 생성 17 제 4 장 사용자 평가 및 결과 19 4.1 SUS 측정 방법 19 4.2 사용자 평가 20 4.3 결과 21 제 5 장 결론 및 논의 26 Bibliography 28 Abstract 30Maste

3D modeling with silhouettes

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 37-39).With the increasing power of computers and the spread of dedicated graphics hardware, 3D content has become ubiquitous in every field, from medicine to video games. However, designing 3D models remains a time-consuming and costly process, so far limited mainly to professionals who have trained extensively with complex modeling suites. We present a new sketch-based modeling approach which aims to make this process simpler and cheaper for professionals, while also making it easy enough for amateurs to use. In our approach, models are interactively designed by drawing their 2D silhouettes from different views. The core idea of our paper is to restrict the input to 2D operations, removing the need to explicitly create or position 3D elements. To create complex shapes, we allow the user to perform CSG operations on silhouettes. We introduce a new algorithm to handle CSG operations that leverages special properties of silhouette cylinders to convert the CSG problem into one that can be handled entirely with 2D operations, making implementation much simpler and more robust. We also introduce a smoothing operator that can generate a smooth shape that matches a set of input silhouettes. We evaluate our approach by using it to model a random sampling of man-made objects taken from the words in WordNet, and show that all of the tested man-made objects are suitable to being modeled quickly and easily using their silhouettes. We also present a user study that demonstrates that novice users are able to use our implemented modeler more effictively than Google SketchUp, a leading commercial 3D modeler also aimed at novice users.by Alec Rivers.S.M

An Interactive Product Customization Framework for Freeform Shapes

Additive Manufacturing (AM) enables the fabrication of three-dimensional (3D) objects with complex shapes without additional tools and refixturing. However, it is difficult for user to use traditional computer-aided design tools to design custom products. In this paper, we presented a design system to help user design custom 3D printable products on top of some freeform shapes. Users can define and edit styling curves on the reference model using our interactive geometric operations for styling curves. Incorporating with the reference models, these curves can be converted into 3D printable models through our fabrication interface. We tested our system with four design applications including a hollow-patterned bicycle helmet, a T-rex with skin frame structures, a face mask with Voronoi patterns, and an AM-specific night dress with hollow patterns. The executable prototype of the presented design framework used in the customization process is publicly available

An evaluation of user experience with a sketch-based 3D modeling system

Abstract With the availability of pen-enabled digital hardware, sketch-based 3D modeling is becoming an increasingly attractive alternative to traditional methods in many design environments. To date, a variety of methodologies and implemented systems have been proposed that all seek to make sketching the primary interaction method for 3D geometric modeling. While many of these methods are promising, a general lack of end user evaluations makes it difficult to assess and improve upon these methods. Based on our ongoing work, we present the usage and a user evaluation of a sketch-based 3D modeling tool we have been developing for industrial styling design. The study investigates the usability of our techniques in the hands of non-experts by gauging (1) the speed with which users can comprehend and adopt to constituent modeling steps, and (2) how effectively users can utilize the newly learned skills to design 3D models. Our observations and users' feedback indicate that overall users could learn the investigated techniques relatively easily and put them in use immediately. However, users pointed out several usability and technical issues such as difficulty in mode selection and lack of sophisticated surface modeling tools as some of the key limitations of the current system. We believe the lessons learned from this study can be used in the development of more powerful and satisfying sketch-based modeling tools in the future.

Augmented manual fabrication methods for 2D tool positioning and 3D sculpting

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 67-75).Augmented manual fabrication involves using digital technology to assist a user engaged in a manual fabrication task. Methods in this space aim to combine the abilities of a human operator, such as motion planning and large-range mechanical manipulation, with technological capabilities that compensate for the operator's areas of weakness, such as precise 3D sensing, manipulation of complex shape data, and millimeter-scale actuation. This thesis presents two new augmented manual fabrication methods. The first is a method for helping a sculptor create an object that precisely matches the shape of a digital 3D model. In this approach, a projector-camera pair is used to scan a sculpture in progress, and the resulting scan data is compared to the target 3D model. The system then computes the changes necessary to bring the physical sculpture closer to the target 3D shape, and projects guidance directly onto the sculpture that indicates where and how the sculpture should be changed, such as by adding or removing material. We describe multiple types of guidance that can be used to direct the sculptor, as well as several related applications of this technique. The second method described in this thesis is a means of precisely positioning a handheld tool on a sheet of material using a hybrid digital-manual approach. An operator is responsible for manually moving a frame containing the tool to the approximate neighborhood of the desired position. The device then detects the frame's position and uses digitally-controlled actuators to move the tool within the frame to the exact target position. By doing this in a real time feedback loop, a tool can be smoothly moved along a digitally-specified 2D path, allowing many types of digital fabrication over an unlimited range using an inexpensive handheld tool.by Alec Rivers.Ph.D