BlobTree modelling has been used in several solid modelling packages to rapidly prototype models by making use of boolean and sketch-based modelling. Using these two techniques, a user can quickly create complex models as combinations of simple primitives and sketched objects. Because the BlobTree is based on continuous field-values, it offers a lot of possibilities to create and control smooth transitions between surfaces, something more complicated in other modelling approaches. In addition, the data required to describe a BlobTree is very compact. Despite these advantages, the BlobTree has not yet been integrated into state of the art industrial workflows to create models. This thesis identifies some shortcomings of the BlobTree, presents potential solutions to those problems and demonstrates an application that makes use of the BlobTree's compact representation. A main criticism is that the evaluation of a large BlobTree can be quite expensive, and, therefore, many applications are limited in the complexity of models that can be created interactively. This work presents an alternative way of traversing a BlobTree that lowers the time to calculate field-values by at least an order of magnitude. As a result, the limit of model complexity is raised for interactive modelling applications. In some domains, certain models need more than one designer or engineer to be created. Often, several iterations of a model are shared between multiple participants until it is finalized. Because the description of a BlobTree is very compact, it can be synchronized efficiently in a collaborative modelling environment. This work presents CollabBlob, an approach to collaborative modelling based on the BlobTree. CollabBlob is lock-free, and provides interactive feedback for all the participants, which helps with a fast iteration in the modelling process. In order to extend the range of models that can be created within CollabBlob, two areas of BlobTree modelling are improved in the context of this thesis. CAD modelling often makes use of a feature called filleting to add additional surface features, which could be caused by a manufacturing process. Filleting in general creates smooth transitions between surfaces, something that the BlobTree can do with less mathematical complexity than approaches needed in Constructive Solid Geometry (CSG), in the case of fillets between primitives. However, little research has been done on the construction of fillets between surfaces of a single BlobTree primitive. This work outlines Angle-Based Filleting and the Surface Fillet Curve, two solutions to improve the specification of fillets in the BlobTree. Sketch-based implicit modelling generates 3D shapes from 2D sketches by sampling the drawn shape and using the samples to create the implicit field via variational interpolation. Additional samples inside and outside the sketched shape are needed to generate a field compatible with BlobTree modelling and state of the art approaches use offset curves of the sketch to generate these samples. The approach presented in this work reduces the number of sample points, thus accelerating the interpolation time and improving the resulting implicit field. / Graduate / 0984 / herbert.grasberger@gmail.com

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The area of business process management in general and and especially business process design has only recently discovered potential applications of social software to facilitate and support collaboration [Scheer and Klueckmann, 2009]. This development is also fueled by the practical insight that organizations have experienced top-down approaches in the design and implementation of business processes to be not effective. In fact, many process management initiatives failed due to a lack of acceptance of chosen methods and tools. As a consequence in many organizations so called [Klückmann and Scheer, 2009] "Guerilla approaches" have been followed where individual organizational units introduced their own business process management philosophy and as well techniques and tools that fit their specific needs. However, Klückmann and Scheer [2009] stress the fact that although distributed business process management initiatives should generally not be hindered, it is important to channel and integrate these initiatives towards a more consistent and efficient process management in the large. Business process modeling in this context serves several purposes in the process management cycle. One purpose is the analysis of business processes to uncover potential performance weaknesses and provide a basis for improvements. Another purpose is the unambiguous documentation of business processes as a resource for knowledge transfer, organizational learning and governance. An increasingly important purpose is the use of process models to support the design and engineering of respective enterprise information systems [Davies et al., 2006]. Hence, the complex and abstract nature of process models and the closedness of process modeling environments has prevented them to be broadly accepted and used by non-experts [Nolte et al., 2011] viz the process community in a wider sense. Consequently, process documentation and models in organizations frequently is outdated, incomplete and inconsistent. This model-reality divide in turn leads to even more reluctance towards the adoption of process modeling environments and use of process models. Bridging this model-reality divide by fostering open and fluent col- laboration through adequate features inspired by social software has gained growing attention by academia and industry [Mathiesen et al., 2012]. Although both industry and academia have addressed the need for collaboration support in process modeling only limited insight exists regarding the specific requirements for software-support in collaborative process modeling. This work refers to existing research (e.g. [Mendling et al., 2012; Riemer et al., 2011]) on requirements for software-support in collaborative process modeling and wiki-based process modeling (e.g. [Ghidini et al., 2010; Dengler and Vrandecic, 2011]). and pursues the following goals: (1) gain an understanding of the nature and requirements of collaborative process modeling in practice, (2) investigate how these requirements can be addressed through the design of a wiki-based collaborative process modeling environment, and (3) gain insight how a wiki-based collaborative process modeling environment supports process design activities in practice. To address these goals a design science approach has been followed. Through a systematic literature review and qualitative expert interviews a preliminary understanding of the problem domain and specification of requirements has been achieved. Through the extension and adaption of a well-proven collaboration platform (a wiki engine) for process modeling support several of the previously identified design issues have been addressed. In particular, issues regarding the flexible integration of a visual process modeling interface component into a collaboration environment and issues regarding concurrent scenarios in process modeling have been discussed in detail and realized partly on a technical level. Two major software components have been developed for the support of collaborative process modeling. First, a light-weight and easily integratable user-interface component for process model creation has been developed and integrated into the collaboration environment (a wiki engine). Second, the identification and handling of concurrent situations when multiple modelers access and modify a process model page has been implemented on an element level which allows for the interactive resolution and semi-automatic merging of conflicting revisions of a process model. Case-studies in an industrial and an academic setting provided valuable insights in the practice of collaborative process modeling and gave feedback on the applicability of a wiki-based approach. The first case-study of a process re-design in the recruiting department of an office supply manufacturing company in Hungary describes the insights gained during a long-term collaboration within a small group. Findings were especially valuable for further enhancements of the software and an understanding of practical requirements in iterative model creation and validation. The second case-study in the context of two bachelor and master courses in information system design has lead to insights regarding the requirements in highly dynamic collaboration scenarios in small groups and large groups but as well regarding the efficiency and effectiveness of wiki-based process modeling in collaborative learning processes. (author's abstract)

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