Tolerance Zone-Based Grouping Method for Online Multiple Overtracing Freehand Sketches

Multiple overtracing strokes are common drawing behaviors in freehand sketching; that is, additional strokes are often drawn repeatedly over the existing ones to add more details. This paper proposes a method based on stroke-tolerance zones to group multiple overtraced strokes which are drawn to express a 2D primitive, aiming to convert online freehand sketches into 2D line drawings, which is a base for further 3D reconstruction. Firstly, after the user inputs a new stroke, a tolerance zone around the stroke is constructed by reference to its polygonal approximation points obtained from the stroke preprocessing. Then, the input strokes are divided into stroke groups, each representing a primitive through the stroke grouping process based on the overtraced ratio of two strokes. At last, each stroke group is fitted into one or more 2D geometric primitives including line segments, polylines, ellipses, and arcs. The proposed method groups two strokes together based on their screen-space proximity directly instead of classifying and fitting them firstly, so that it can group strokes of arbitrary shapes. A sketch-recognition prototype system has been implemented to test the effectiveness of the proposed method. The results showed that the proposed method could support online multiple overtracing freehand sketching with no limitation on drawing sequence, but it only deals with strokes with relatively high overtraced ratio

Envisioning sketch recognition : a local feature based approach to recognizing informal sketches

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 89-94).Hand drawn sketches are an important part of the early design process and are an important aspect of creative design. They are used in many fields including electrical engineering, software engineering and web design. Recognizing shapes in these sketches is a challenging task due to the imprecision with which they are drawn. We tackle this challenge with a visual approach to recognition. The approach is based on a representation of a sketched shape in terms of the visual parts it is made of. By taking this part-based visual approach we are able to recognize shapes that are extremely difficult to recognize with current sketch recognition systems that focus on the individual strokes.by Michael Oltmans.Ph.D

A fast approach for perceptually-based fitting strokes into elliptical arcs

Fitting elliptical arcs to strokes of an input sketch is discussed. We describe an approach which automatically combines existing algorithms to get a balance of speed and precision. For measuring precision, we introduce fast metrics which are based on perceptual criteria and are tolerant of sketching imperfections. We return a likelihood estimate based on these metrics rather than deterministic yes/no result, in order that the approach can be used in higher-level collaborative-decision recognition flows.1) Ramon y Cajal Scholarship Programme 2) "Pla de Promoció de la Investigació de la Universitat Jaume I", project P1 1B2010-0

Exploring local regularities for 3D object recognition

In order to find better simplicity measurements for 3D object recognition, a new set of local regularities is developed and tested in a stepwise 3D reconstruction method, including localized minimizing standard deviation of angles(L-MSDA), localized minimizing standard deviation of segment magnitudes(L-MSDSM), localized minimum standard deviation of areas of child faces (L-MSDAF), localized minimum sum of segment magnitudes of common edges (L-MSSM), and localized minimum sum of areas of child face (L-MSAF). Based on their effectiveness measurements in terms of form and size distortions, it is found that when two local regularities: L-MSDA and L-MSDSM are combined together, they can produce better performance. In addition, the best weightings for them to work together are identified as 10% for L-MSDSM and 90% for L-MSDA. The test results show that the combined usage of L-MSDA and L-MSDSM with identified weightings has a potential to be applied in other optimization based 3D recognition methods to improve their efficacy and robustness

Shape exploration in product design: assisting transformation in pictorial representations

The sketching of pictorial representations forms a key technique for professional designers in the generation and exploration of product shape. It allows ideas of shape to be externalised and communicated, but more importantly, sketched pictorial representations can operate to assist designers' creative thinking. While computer aided design tools have a proven capability to support the development of design ideas, there is still much scope to develop computer based tools that support the free-flowing exploratory thinking that characterises shape generation and shape exploration in product design. Far from being a straight-jacket in creative design, shape rules have significant potential to bridge the gap between traditional sketching techniques and modern computational methods of design. This thesis presents an inquiry into the exploitation of shape rules within product design. It includes studies of design sketches by professional designers and these inform the development of a theoretical model for assisting design transformation. A formal model of exploration is proposed with two mechanisms; shape decomposition and shape transformation. This model is applied using pictorial representations which may be seen as the computing equivalent of freehand sketches, and reveals new strategies for systematic shape generation and exploration in product design

A digital prototype for collaborative conceptual design in the Thai AEC sector

The construction industry is currently driving to reach a high level of achievement for future sustainable built environments. The UK and USA models for the building design and construction process have been developed to enable relevant stakeholders to work closely from the beginning of a project. Indeed, design production is particularly significant, particularly at the concept design stage, as design decisions cost less to change and there is greater opportunity for change at the concept design stage. These are important considerations for this study. In addition, collaboration can significantly reduce redundant loops of performance in the subsequent processes leading to savings both in cost and time. However, the traditional design phases in the USA and Thailand have faced barriers due to silos of effort, a lack of overall project awareness, inefficient collaboration between silos, and poor communication among silos due to the fragmentation of the functional disciplines involved.Furthermore, stakeholders working in partnership in the AEC industry are connected together in a complex way so information sharing is not straightforward; however, they are now supported by digital tools and communication technology, which can mediate this collaborative process. Effective collaboration can be promoted by technology through existing digital tools, for example, CAD or BIM. These tools can enable important increases in productivity through the strategic sharing of information. However, these are not appropriate tools for the concept design stage due to the complex information involved and the difficult user interfaces. This difficult interface leads to consumption of memory and an obstruction of the mental workflow, which does not support designers at the concept design stage. Moreover, the purpose of collaboration among multidisciplinary and multi-functional teams is to enable the integration of other disciplines, to maintain and sustain knowledge and information sharing, and to predict colleague behaviour. Knowledge sources and the retrieval of knowledge and information are significant; however, communication has pros and cons, and current tools, such as email or instant messaging, are difficult to use for the purpose of collaboration.Therefore, this research has developed an innovative digital tool to facilitate collaboration and support designers at the concept design stage. This tool enhances the creative thinking process by emphasising the streaming of the cognitive workload. In addition, collaborative communication supports the creation and structure of contents, posts and replies and supports designers to retrieve information. Collaborators/stakeholders can therefore share space and information. The research methodology for this study was designed to collect data in Thailand; it included the design and development of a prototype, and an evaluation of a case study in Thailand. The prototype is the first pilot of the digital tool to support designers at the concept design stage and could be further developed for use in practice

New grouping and fitting methods for interactive overtraced sketches

This paper describes a new method for recognizing overtraced strokes to 2D geometric primitives, which are further interpreted as 2D line drawings. This method can support rapid grouping and fitting of overtraced polylines or conic curves based on the classified characteristics of each stroke during its preprocessing stage. The orientation and its endpoints of a classified stroke are used in the stroke grouping process. The grouped strokes are then fitted with 2D geometry. This method can deal with overtraced sketch strokes in both solid and dash linestyles, fit grouped polylines as a whole polyline and simply fit conic strokes without computing the direction of a stroke. It avoids losing joint information due to segmentation of a polyline into line-segments. The proposed method has been tested with our freehand sketch recognition system (FSR), which is robust and easier to use by removing some limitations embedded with most existing sketching systems which only accept non-overtraced stroke drawing. The test results showed that the proposed method can support freehand sketching based conceptual design with no limitations on drawing sequence, directions and overtraced cases while achieving a satisfactory interpretation rate

形状と位相の編集が可能な手書きCADインターフェースの実現に関する研究

デジタルペンタブレットやタッチディスプレイの普及に伴い，スケッチベースのインタラクティブなCAD（Computer-aided design）ユーザインターフェースが注目を集めている．しかしながら，既存のインターフェースSKIT（Sketch Input Tracer）では，重ね書きストロークの入力による編集操作は，一度に単一の幾何オブジェクトしか対象とすることができないという限界がある．この限界を克服するため本研究ではまず準備として，「自由曲線整形」，「サブ曲線同定」，「IFGS」という要素技術を提案し，SKITの要素技術を拡充する．その上で，2次元CADシステムで使用するための汎用的なスケッチベースのインターフェースを新たに提案する．これにより，重ね書きによって複数の幾何オブジェクトの形状と位相を同時に修正することができるスケッチベースの編集操作が実現される．提案インターフェースは，SKITのファジィ論理に基づく戦略に基づいて開発される．これにより，汎用手書きCADインターフェースで必要となる手書き操作が網羅されることとなる．提案インターフェースを使用することで，ユーザはラフスケッチから始めて，重ね書きを繰り返しながら詳細なデザインを作成するといった作図を創造的に行うことが可能となる．実験により，熟練者が提案インターフェースを制御することができ，初心者がその制御に慣れることが可能であることを示す．With the widespread use of digital pen tablets and touch displays, sketch-based interactive computer-aided design (CAD) user interfaces have attracted considerable attention. In an existing interface called the Sketch Input Tracer (SKIT), however, the editing operation performed via an over-sketching stroke can target only a single geometric object at any given time. To overcome this limitation, in this paper, free-curve shaping, sub-curve identifier, and IFGS are proposed as preparations, which extends elemental techniques in existing SKIT. After that I propose a new general-purpose sketch-based interface developed for use in two-dimensional CAD systems. In the proposed interface, a sketch-based editing operation can simultaneously modify the geometry and topology of multiple geometric objects via over-sketching. The interface was developed based on the fuzzy logic-based strategy of SKIT. With this interface, a user can draw in a creative manner; for example, they can begin with a rough sketch and progressively create a detailed design through repeated over-sketches. The results of experiments conducted demonstrate that experts can control the proposed interactive drawing interface and beginners can habituate to controlling it.室蘭工業大学 (Muroran Institute of Technology)博士（工学