Abstract
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Abstract
To understand the impact of emotionally driven games on player experience, we developed a procedural horror game (Vanish) capable of run-time level, asset, and event generation. Vanish was augmented to interpret players' physiological data as a simplified emotional state, mapping it to a set of adaptation rules that modify the player experience. To explore the effects of adaptation mechanisms on player experience, we conducted a mixed-methods study on three different versions of the game, two of which integrated varying biofeedback mechanisms. Players' affective experiences were objectively measured by analysing physiological data. Additionally, subjective experience was recorded through the use of the Game Experience Questionnaire. Our study confirmed that biofeedback functionality had a statistically significant effect on the ratings of player experience dimensions: immersion, tension, positive affect, and negative affect. Furthermore, participants reported noticeable differences in player experience, favouring the added depth present in the biofeedback-enabled iterations of the game. In the future, these conclusions will help to develop more immersive and engaging player experiences.

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Abstract
This paper proposes a haptic interaction system for Virtual Reality (VR) based on a combination of tracking devices for hands and objects and a real-to-virtual mapping system for user redirection. In our solution the user receives haptic stimuli by manipulating real objects mapped to virtual objects. This solution departs from systems that rely on haptic devices (e.g., haptic gloves) as interfaces for the user to interact with objects in the Virtual Environment (VE). As such, the proposed solution makes use of direct haptics (touching) and redirection techniques to guide the user through the virtual environment. Using the mapping framework, when the user touches a virtual object in the VE, he will simultaneously be physically touching the equivalent real object. A relevant feature of the framework is the possibility to define a warped mapping between the real and virtual worlds, such that the relation between the user and the virtual space can be different from the one between the user and the real space. This is particularly useful when the application requires the emulation of large virtual spaces but the physical space available is more confined. To achieve this, both the user's hands and the objects are tracked. In the presented prototype we use a head-mounted depth sensor (i.e., Leap Motion) and a depth-sensing camera (i.e., Kinect). To assess the feasibility of this solution, a functional prototype and a room setup with core functionality were implemented. The test sessions with users evaluated the mapping accuracy, the user execution time and the awareness of the user regarding the warped space when performing tasks with redirection. The results gathered indicate that the solution can be used to provide direct haptic feedback in VR applications and for warping space perception within certain limits.

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Abstract
In this manuscript, we propose to adapt the B-Spline Explicit Active Surfaces (BEAS) framework for semi-automatic kidney segmentation in computed tomography (CT) images. To study the best energy functional for kidney CT extraction, three different localized region-based energies were implemented within the BEAS framework, namely localized Chan-Vese, localized Yezzi, and signed localized Yezzi energies. Moreover, a novel gradient-based regularization term is proposed. The method was applied on 18 kidneys from 9 CT datasets, with different image properties. Several energy combinations were contrasted using surface-based comparison against ground truth meshes, assessing their accuracy and robustness against surface initialization. Overall, the hybrid energy functional combining the localized signed Yezzi energy with gradient-based regularization simultaneously showed the highest accuracy and the lowest sensitivity to the initialization. Volumetric analysis demonstrated the feasibility of the method from a clinical point of view, with similar reproducibility to manual observers.