NUI-Marbling

DOI: http://dx.doi.org/10.14236/ewic/EVA2017.7 NUI-Marbling Marina Sparvoli UFABC Santo André, SP, Brazil marina.sparvoli@ufabc.edu.br Candy Tenorio UFABC Santo André, SP, Brazil candy.tenorio@ufabc.edu.br 1. INTRODUCTION   Natural user interface (NUI) can be defined as human-computer interaction systems in which the user employs intuitive actions based on the human behaviour. Common examples of NUI interfaces are those ones that use multi-touch screens, gesture and sound recognition systems, and painting tablet devices. Paper marbling is a painting approach in which the artist uses proper tools – as combs and brushes – to interact with the paints deposited on an aqueous surface, producing thus marble-like paintings. These paintings are then transferred to an absorbent paper, which are used, for instance, as book cover. In this work, we present a computational marbling system that incorporate NUI to easy the generation of marbling patterns.    The artistic results are presented in Figures 3 to 6. 4. ACKNOWLEDGMENTS The user-interface, presented in Figure 1, provides the main marbling options in one single window. Namely, the system is composed of two regions: the design area, where the artist paints her digital marbling patterns; and the painting toolbar, which offers tools employed by the artists and to adjust the marbling simulation. User input is done by a graphics tablet model Wacom PTK840 with 12×8 inches (Figure 2). We thank the local artists Mirtes Ribeiro, Marina Sparvoli, Fernanda Wassano and Ana Queiroz for voluntarily using our tool and producing the artistic results presented in this paper. 5. REFERENCES Jin, X., Chen, S., Mao, X. (2007) Computergenerated marbling textures: A GPU-based design system. Computer Graphics and Applications, IEEE 27(2), pp. 78–84. Our marbling system requires heavily processing and data exchanges between the user interface (paint rendering and processing input devices) with solver of the Navier-Stokes equations. Specifically, the process to create a marbling relies on: Stam, J. (1999) Stable fluids. In Proceedings of the 26th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH '99). ACM Press/Addison-Wesley Publishing Co., New York, NY, USA, pp. 121–128. The preparation of system to receive the paint by the artist; The computation of the domain transformations and of the fluid density; © Sparvoli et al. Published by BCS Learning and Development Ltd. Proceedings of Proceedings of EVA London 2017, UK The configuration of the graphics objects; The computation of the fluid flow simulation; The conversion of the fluid flow simulation to textures; The generation of the gradient colour paint; The displaying of the final result. Our NUI-marbling system provides a support to GPU-based multilayer paints ensure that the distinct paint colours inserted by the artist are preserved. It is a property of the traditional paper marbling ensured by our approach. The NUI-marbling system was designed to be capable of producing results in real-time and a friendly user interface with support to graphics tablets and multi-touch screen.  João Paulo Gois UFABC Santo André, SP, Brazil joao.gois@ufabc.edu.br Specifically, the domain simulation is discretized into a Cartesian two-dimensional grid, where the velocity field and density field are stored in shader textures. Since fluid flow simulation is executed on the GPU, there is an interaction among all the shader programs (for rendering and also for the fluid simulation) used to provide a real-time feedback to the user. 2. PROCESSING AND DESIGNING  Mario Gazziro UFABC Santo André, SP, Brazil mario.gazziro@ufabc.edu.br 42 NUI-Marbling Mario Gazziro, Candy Tenorio, Lucio Freitas & João Paulo Gois Wigdor, D., Wixon, D. (2011) Brave NUI World: Designing Natural User Interfaces for Touch and Gesture, 1st. ed. San Francisco, CA, USA: Morgan Kaufmann Publishers Inc. Figure 4: Sakura blossom. Figure 1: The interface of the application. Figure 5: Tulips. Figure 2: Natural interaction with a graphics tablet. Figure 6: Chocolate Art Lady. Figure 3: Two-Hearts painting. 43