Polycube Simplification for Coarse Layouts of Surfaces and Volumes.

Abstract: Representing digital objects with structured meshes that embed a coarse block decomposition is a relevant problem in applications like computer animation, physically-based simulation and Computer Aided Design (CAD). One of the key ingredients to produce coarse block structures is to achieve a good alignment between the mesh singularities (i.e., the corners of each block). In this paper we improve on the polycube-based meshing pipeline to produce both surface and volumetric coarse block-structured meshes of general shapes. To this aim we add a new step in the pipeline. Our goal is to optimize the positions of the polycube corners to produce as coarse as possible base complexes. We rely on re-mapping the positions of the corners on an integer grid and then using integer numerical programming to reach the optimal. To the best of our knowledge this is the first attempt to solve the singularity misalignment problem directly in polycube space. Previous methods for polycube generation did not specifically address this issue. Our corner optimization strategy is efficient and requires a negligible extra running time for the meshing pipeline. In the paper we show that our optimized polycubes produce coarser block structured surface and volumetric meshes if compared with previous approaches. They also induce higher quality hexahedral meshes and are better suited for spline fitting because they reduce the number of splines necessary to cover the domain, thus improving both the efficiency and the overall level of smoothness throughout the volume.

Authors: G. Cherchi, M. Livesu, R. Scateni.
Polycube Simplification for Coarse Layouts of Surfaces and Volumes.
Computer Graphics Forum, 35(5):11-20, (SGP 2016, Berlino, Germania).
Wiley, June 2016.

AR Turn-by-turn navigation in small urban areas and information browsing

Abstract: Navigation systems allow to discover cities and their urban areas easily and quickly, finding the shortest path to reach them and giving directions to users saving their time and energy. At present time, these systems are based over streets maps offered by the major mapping services like Tele Atlas, Navteq or OpenStreetMap. In recent years, thanks to the Google StreetView service it has been possible to discover main cities locations both indoor and outdoor. What is missing in this frame is the possibility to map small urban areas of small and medium sized cities, due to their lack of relevance for the big players. In this cities there could be very interesting areas for tourists. Example locations could be botanical gardens, archeological sites, protected natural areas among others. In this work we tried to set up a navigation system for limited extensions inside urban areas which permits to wander around and gives access to related information using augmented reality techniques. Due to the possible poor wireless coverage in these locations we designed an application that stores all required data on the user’s device, splitting the information in packages according to the chosen language. A key issue was to achieve good results combining all these features in a single device with a small display, overwhelming the constraints due to the mobile environment.

Authors: G. Cherchi, F. Sorrentino, R. Scateni.
AR Turn-by-turn navigation in small urban areas and information browsing.
EuroGraphics Italian Chapter 2014 (short papers), 37-40.
Cagliari, Italia, Settembre 2014.