Abstract
Stereoscopic tabletops offer unique visualization capabilities, enabling users to perceive virtual objects as if they were lying above the surface. While allowing virtual objects to coexist with user actions in the physical world, interaction with these virtual objects above the surface presents interesting challenges. In this paper, we aim to understand which approaches to 3D virtual object manipulations are suited to this scenario. To this end, we implemented five different techniques based on the literature. Four are mid-air techniques, while the remainder relies on multi-touch gestures, which act as a baseline. Our setup combines affordable non-intrusive tracking technologies with a multi-touch stereo tabletop, providing head and hands tracking, to improve both depth perception and seamless interactions above the table. We conducted a user evaluation to find out which technique appealed most to participants. Results suggest that mid-air interactions, combining direct manipulation with six degrees of freedom for the dominant hand, are both more satisfying and efficient than the alternatives tested.

Abstract
The number and size of 3D object repositories have been increasing at a considerable rate. Consequently, finding a specific 3D model in such collections is getting more difficult. Current 3D search engines do not take advantage of novel interaction technologies, usually presenting query results in grids of thumbnails. This greatly hinders objects' interpretation and allows little to none manipulation at all. Immersive environments are believed as promising solutions for displaying 3D models, allowing complete representations of the models. These environments can be enhanced with multimodal techniques for a more natural interaction. In this paper we present a prototype that uses immersive visualization and mid-air interactions to explore query results in a dataset with 3D objects, using one of four different visualization modes. We evaluated these modes with 29 users and concluded that our immersive approaches are preferred by users and, albeit novel, perform at par relatively to traditional bi-dimensional grids with thumbnails.

Abstract
The Societas Europaea Herpetologica (SEH) decided in 2006 through its Mapping Committee to implement the New Atlas of Amphibians and Reptiles of Europe (NA2RE: http://na2re.ismai.pt) as a chorological database system. Initially designed to be a system of distributed databases, NA2RE quickly evolved to a Spatial Data Infrastructure, a system of geographically distributed systems. Each individual system has a national focus and is implemented in an online network, accessible through standard interfaces, thus allowing for interoperable communication and sharing of spatial-temporal data amongst one another. A Web interface facilitates the access of the user to all participating data systems as if it were one single virtual integrated data-source. Upon user request, the Web interface searches all distributed data-sources for the requested data, integrating the answers in an always updated and interactive map. This infrastructure implements methods for fast actualisation of national observation records, as well as for the use of a common taxonomy and systematics. Using this approach, data duplication is avoided, national systems are maintained in their own countries, and national organisations are responsible for their own data curation and management. The database could be built with different representation levels and resolution levels of data, and filtered according to species conservation matters. We present the first prototype of NA2RE, composed of the last data compilation performed by the SEH (Sillero et al., 2014). This system is implemented using only open source software: PostgreSQL database with PostGIS extension, Geoserver, and OpenLayers.

Abstract
Pectus excavatum is the most common deformity of the thorax and usually comprises Computed Tomography (CT) examination for pre-operative diagnosis. Aiming at the elimination of the high amounts of CT radiation exposure, this work presents a new methodology for the replacement of CT by a laser scanner (radiation-free) in the treatment of pectus excavatum using personally modeled prosthesis. The complete elimination of CT involves the determination of ribs external outline, at the maximum sternum depression point for prosthesis placement, based on chest wall skin surface information, acquired by a laser scanner. The developed solution resorts to artificial neural networks trained with data vectors from 165 patients. Scaled Conjugate Gradient, Levenberg-Marquardt, Resilient Back propagation and One Step Secant gradient learning algorithms were used. The training procedure was performed using the soft tissue thicknesses, determined using image processing techniques that automatically segment the skin and rib cage. The developed solution was then used to determine the ribs outline in data from 20 patient scanners. Tests revealed that ribs position can be estimated with an average error of about 6.82 +/- 5.7 mm for the left and right side of the patient. Such an error range is well below current prosthesis manual modeling (11.7 +/- 4.01 mm) even without CT imagiology, indicating a considerable step forward towards CT replacement by a 3D scanner for prosthesis personalization.

Abstract
Nowadays, different techniques are available for manufacturing full-arch implantsupported prosthesis, many of them based on an impression procedure. Nevertheless, the long-term success of the prosthesis is highly influenced by the accuracy during such process, being affected by factors such as the impression material, implant position, angulation and depth. This paper investigates the feasibility of a 3D electromagnetic motion tracking system as an acquisition method for modeling such prosthesis. To this extent, we propose an implant acquisition method at the patient mouth, using a specific prototyped tool coupled with a tracker sensor, and a set of calibration procedures (for distortion correction and tool calibration), that ultimately obtains combined measurements of the implant's position and angulation, and eliminating the use of any impression material. However, in the particular case of the evaluated tracking system, the order of magnitude of the obtained errors invalidates its use for this specific application. © 2014 Taylor & Francis Group.

Abstract
Background: Precise needle puncture of renal calyces is a challenging and essential step for successful percutaneous nephrolithotomy. This work tests and evaluates, through a clinical trial, a real-time navigation system to plan and guide percutaneous kidney puncture. Methods: A novel system, entitled i3DPuncture, was developed to aid surgeons in establishing the desired puncture site and the best virtual puncture trajectory, by gathering and processing data from a tracked needle with optical passive markers. In order to navigate and superimpose the needle to a preoperative volume, the patient, 3D image data and tracker system were previously registered intraoperatively using seven points that were strategically chosen based on rigid bone structures and nearby kidney area. In addition, relevant anatomical structures for surgical navigation were automatically segmented using a multi-organ segmentation algorithm that clusters volumes based on statistical properties and minimum description length criterion. For each cluster, a rendering transfer function enhanced the visualization of different organs and surrounding tissues. Results: One puncture attempt was sufficient to achieve a successful kidney puncture. The puncture took 265 seconds, and 32 seconds were necessary to plan the puncture trajectory. The virtual puncture path was followed correctively until the needle tip reached the desired kidney calyceal. Conclusions: This new solution provided spatial information regarding the needle inside the body and the possibility to visualize surrounding organs. It may offer a promising and innovative solution for percutaneous punctures.