@article {ipa|Conceptual design of shapes in Virtual Environments through the re-use of heterogeneous data|2016, title = {Conceptual design of shapes in Virtual Environments through the re-use of heterogeneous data}, year = {2016}, month = {November}, pages = {23 p.}, institution = {CNR-IMATI}, address = {Genova}, abstract = {

Today, digital data such as 2D images, 3D meshes and 3D point clouds are widely used to design Virtual Environments (VE). Most of the time, only one type of those multimodal data is used to describe and specify the shapes of the objects. However, a single object can be seen as a combination of components linked with constraints specifying the relationships and the rigid transformations defining their arrangement. Thus, the definition of news methods able to combine any kind of multimodal data in an easy way would allow nonexperts of VE to rapidly mock-up objects and scenes. In this paper, we propose a new shape description model together with its associated constraints toolbox enabling the description of complex shapes from multimodal data. Not only rigid transformations are considered but also scale modifications according to the specified context of the constraint setting. The heterogeneous virtual objects (i.e. composed by scalable multimodal components) then result from the resolution of a constraint satisfaction problem through an optimization approach. The proposed approach is illustrated with examples obtained with our prototype software.

}, keywords = {Virtual Reality}, url = {http://irs.imati.cnr.it/reports/irs16-17}, author = {J-P. Pernot and B. Falcidieno and F. Giannini and Z. Li and P. V{\'e}ron} } @article {ipa|Feature curve identification in archaeological fragments using an extension of the Hough transform|2016, title = {Feature curve identification in archaeological fragments using an extension of the Hough transform}, year = {2016}, month = {July}, pages = {19 p.}, institution = {CNR-IMATI}, address = {Genova}, abstract = {

The use of computer graphics techniques in cultural heritage (CH) has led to impressive improvements in technologies related to digital acquisition and rendering of 3D CH data. Digitized artefacts are becoming widely available for access and reuse, thus increasing the need of tools able to support comparative shape analysis. As 3D artefacts are often worn, eroded and broken, these tools cannot take advantage of existing methods based on exact matching but they rather require new approaches able to identify partial features in portions of models thus leading to a double partiality of the matching problem, in terms of both features and models In this context, we propose a method based on a novel generalization of the Hough transform technique able to identify and localize semantic features like anatomical features, ornaments, or decorations on digital artefacts or fragments, even if the features are partially damaged or incomplete. The major advantages of using a method based on the Hough transform technique are the relative robustness to noise and the recognition power also in the case of partial features. Our experiments on digital models of real artefacts are encouraging and show the potential of the method, which can work on both 3D meshes and point clouds.

}, keywords = {Hough transform}, url = {http://irs.imati.cnr.it/reports/irs16-09}, author = {ML. Torrente and S. Biasotti and B. Falcidieno} } @article {ipa|Mapping aesthetic properties to 3D free form shapes through the use of a machine learning based framework|2016, title = {Mapping aesthetic properties to 3D free form shapes through the use of a machine learning based framework}, year = {2016}, month = {November}, pages = {27 p.}, institution = {CNR-IMATI}, type = {Working paper}, address = {Genova}, abstract = {

Current production is moving from the mass production concept to the product customization and personalization. Customers are not anymore only buyers. Not only they are becoming actors within the Product Development Process (PDP) but, thanks to new production technologies like 3D printers, they can be both designers and producers. In this scenario, the development of user-friendly design tools is crucial. Declarative approaches are suitable and can address such requirements. They exploit generally understood and shared concepts closer to the way people perceive shapes than to the way shapes are modeled with complex geometric models. To this aim, this paper presents a generic framework for understanding the shape characteristics associated to perceptual/aesthetic properties of 3D free form shapes. This framework is used to investigate whether there is a common judgment to characterize the flatness of surfaces and which are the surface shape characteristics affecting the flatness perception? From the experiments, it results that the size and transition of the surrounding influence the perception of the flatness of a given surface strengthening the classification consistency.

}, keywords = {Machine Learning Application}, url = {http://irs.imati.cnr.it/reports/irs16-16}, author = {A. Petrov and J-P. Pernot and F. Giannini and B. Falcidieno} } @article {ipa|A study of the state of the art of process planning for additive manufacturing|2016, title = {A study of the state of the art of process planning for additive manufacturing}, year = {2016}, month = {May}, pages = {16 p.}, institution = {CNR-IMATI}, type = {Working paper}, address = {Genova}, abstract = {

In the manufacturing industry the term Process Planning (PP) is concerned with determining the sequence of individual manufacturing operations needed to produce a given part or product with a certain machine. In this technical report we propose a preliminary analysis of scientic literature on the topic of process planning for Additive Manufacturing (AM) technologies (i.e. 3D printing). We observe that the process planning for additive manufacturing processes consists of a small set of standard operations (repairing, orientation, supports, slicing and toolpath generation). We analyze each of them in order to emphasize the most critical aspects of the current pipeline as well as highlight the future challenges for this emerging manufacturing technology.

}, keywords = {Process planning}, url = {http://irs.imati.cnr.it/reports/irs16-04}, author = {M. Livesu and M. Attene and M. Spagnuolo and B. Falcidieno} }