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Animation and Interaction of Responsive, Expressive, and Tangible 3D Virtual Characters

  • Autores: Adso Fernández Baena
  • Directores de la Tesis: David Miralles Esteban (dir. tes.)
  • Lectura: En la Universitat Ramon Llull ( España ) en 2015
  • Idioma: inglés
  • Materias:
  • Enlaces
    • Tesis en acceso abierto en: TDX
  • Resumen
    • This thesis is framed within the field of 3D Character Animation. Virtual characters are used in many Human Computer Interaction applications such as video games and serious games. Within these virtual worlds they move and act in similar ways to humans controlled by users through some form of interface or by artificial intelligence. This work addresses the challenges of developing smoother movements and more natural behaviors driving motions in real-time, intuitively, and accurately. The interaction between virtual characters and intelligent objects will also be explored. With these subjects researched the work will contribute to creating more responsive, expressive, and tangible virtual characters. The navigation within virtual worlds uses locomotion such as walking, running, etc. To achieve maximum realism, actors' movements are captured and used to animate virtual characters. This is the philosophy of motion graphs: a structure that embeds movements where the continuous motion stream is generated from concatenating motion pieces. However, locomotion synthesis, using motion graphs, involves a tradeoff between the number of possible transitions between different kinds of locomotion, and the quality of these, meaning smooth transition between poses. To overcome this drawback, we propose the method of progressive transitions using Body Part Motion Graphs (BPMGs). This method deals with partial movements, and generates specific, synchronized transitions for each body part (group of joints) within a window of time. Therefore, the connectivity within the system is not linked to the similarity between global poses allowing us to find more and better quality transition points while increasing the speed of response and execution of these transitions in contrast to standard motion graphs method. Secondly, beyond getting faster transitions and smoother movements, virtual characters also interact with each other and with users by speaking. This interaction requires the creation of appropriate gestures according to the voice that they reproduced. Gestures are the nonverbal language that accompanies voiced language. The credibility of virtual characters when speaking is linked to the naturalness of their movements in sync with the voice in speech and intonation. Consequently, we analyzed the relationship between gestures, speech, and the performed gestures according to that speech. We defined intensity indicators for both gestures (GSI, Gesture Strength Indicator) and speech (PSI, Pitch Strength Indicator). We studied the relationship in time and intensity of these cues in order to establish synchronicity and intensity rules. Later we adapted the mentioned rules to select the appropriate gestures to the speech input (tagged text from speech signal) in the Gesture Motion Graph (GMG). The evaluation of resulting animations shows the importance of relating the intensity of speech and gestures to generate believable animations beyond time synchronization. Subsequently, we present a system that leads automatic generation of gestures and facial animation from a speech signal: BodySpeech. This system also includes animation improvements such as: increased use of data input, more flexible time synchronization, and new features like editing style of output animations. In addition, facial animation also takes into account speech intonation. Finally, we have moved virtual characters from virtual environments to the physical world in order to explore their interaction possibilities with real objects. To this end, we present AvatARs, virtual characters that have tangible representation and are integrated into reality through augmented reality apps on mobile devices. Users choose a physical object to manipulate in order to control the animation. They can select and configure the animation, which serves as a support for the virtual character represented. Then, we explored the interaction of AvatARs with intelligent physical objects like the Pleo social robot. Pleo is used to assist hospitalized children in therapy or simply for playing. Despite its benefits, there is a lack of emotional relationship and interaction between the children and Pleo which makes children lose interest eventually. This is why we have created a mixed reality scenario where Vleo (AvatAR as Pleo, virtual element) and Pleo (real element) interact naturally. This scenario has been tested and the results conclude that AvatARs enhances children's motivation to play with Pleo, opening a new horizon in the interaction between virtual characters and robots.


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