Makoto Okabe

Interactive Design of Botanical Trees using Freehand Sketches and Example‐based Editing

We present a system for quickly and easily designing three-dimensional (3D) models of botanical trees using freehand sketches and additional example-based editing operations. The system generates a 3D geometry from a twodimensional (2D) sketch using the assumption that trees spread their branches so that the distances between the branches are as large as possible. The user can apply additional gesture-based editing operations such as adding, cutting, and erasing branches. Our system also supports example-based editing modes in which many branches and leaves are generated by using a manually designed tree as an example. User experience demonstrates that our interface lets novices design a variety of reasonably natural-looking trees interactively and quickly.

Floral diagrams and inflorescences: interactive flower modeling using botanical structural constraints

We present a system for modeling flowers in three dimensions quickly and easily while preserving correct botanical structures. We use floral diagrams and inflorescences, which were developed by botanists to concisely describe structural information of flowers. Floral diagrams represent the layout of floral components on a single flower, while inflorescences are arrangements of multiple flowers. Based on these notions, we created a simple user interface that is specially tailored to flower editing, while retaining a maximum variety of generable models. We also provide sketching interfaces to define the geometries of floral components. Separation of structural editing and editing of geometry makes the authoring process more flexible and efficient. We found that even novice users could easily design various flower models using our technique. Our system is an example of application-customized sketching, illustrating the potential power of a sketching interface that is carefully designed for a specific application.

Haptic feedback for pen computing: directions and strategies

We seek to improve the xperience of using pen computing devices by augmenting them with haptic, tactile feedback displays. We present the design of the haptic display for pen computers, and explore interaction techniques that allow users to feel GUI elements, textures, photographs and other interface elements with a pen. We discuss research directions in haptic displays for pen devices and report results of an early experimental study that evaluated the benefits of tactile feedback in pen computing.

Volumetric illustration: designing 3D models with internal textures

This paper presents an interactive system for designing and browsing volumetric illustrations. Volumetric illustrations are 3D models with internal textures that the user can browse by cutting the models at desired locations. To assign internal textures to a surface mesh, the designer cuts the mesh and provides simple guiding information to specify the correspondence between the cross-section and a reference 2D image. The guiding information is stored with the geometry and used during the synthesis of cross-sectional textures. The key idea is to synthesize a plausible cross-sectional image using a 2D texture-synthesis technique, instead of sampling from a complete 3D RGB volumetric representation directly. This simplifies the design interface and reduces the amount of data, making it possible for non-experts to rapidly design and use volumetric illustrations. We believe that our system can enrich human communications in various domains, such as medicine, biology, and geology.

Lapped solid textures: filling a model with anisotropic textures

We present a method for representing solid objects with spatially-varying oriented textures by repeatedly pasting solid texture exemplars. The underlying concept is to extend the 2D texture patch-pasting approach of lapped textures to 3D solids using a tetrahedral mesh and 3D texture patches. The system places texture patches according to the user-defined volumetric tensor fields over the mesh to represent oriented textures. We have also extended the original technique to handle nonhomogeneous textures for creating solid models whose textural patterns change gradually along the depth fields. We identify several texture types considering the amount of anisotropy and spatial variation and provide a tailored user interface for each. With our simple framework, large-scale realistic solid models can be created easily with little memory and computational cost. We demonstrate the effectiveness of our approach with several examples including trees, fruits, and vegetables.

Illumination Brush: Interactive Design of All-Frequency Lighting

We present an appearance-based user interface for artists to efficiently design customized image-based lighting environments. 1 Our approach avoids typical iterations of parameter editing, rendering, and confirmation by providing a set of intuitive user interfaces for directly specifying the desired appearance of the model in the scene. Then the system automatically creates the lighting environment by solving the inverse shading problem. To obtain a realistic image, all-frequency lighting is used with a spherical radial basis function (SRBF) representation. Rendering is performed using precomputed radiance transfer (PRT) to achieve a responsive speed. User experiments demonstrated the effectiveness of the proposed system compared to a previous approach.

Interactive design of botanical trees using freehand sketches and example-based editing

We present a system for quickly and easily designing three-dimensional (3D) models of botanical trees using free-hand sketches and additional example-based editing operations. The system generates a 3D geometry from a two-dimensional (2D) sketch using the assumption that trees spread their branches so that the distances between the branches are as large as possible. The user can apply additional gesture-based editing operations such as adding, cutting, and erasing branches. Our system also supports example-based editing modes in which many branches and leaves are generated by using a manually designed tree as an example. User experience demonstrates that our interface lets novices design a variety of reasonably natural-looking trees interactively and quickly.

Interactive reflection editing

Effective digital content creation tools must be both efficient in the interactions they provide but also allow full user control. There may be occasions, when art direction requires changes that contradict physical laws. In particular, it is known that physical correctness of reflections for the human observer is hard to assess. For many centuries, traditional artists have exploited this fact to depict reflections that lie outside the realm of physical possibility. However, a system that gives explicit control of this effect to digital artists has not yet been described. This paper introduces a system that transforms physically correct reflections into art-directed reflections, as specified by reflection constraints. The system introduces a taxonomy of reflection editing operations, using an intuitive user interface, that works directly on the reflecting surfaces with real-time visual feedback using a GPU. A user study shows how such a system can allow users to quickly manipulate reflections according to an art direction task.

Animating Pictures of Fluid using Video Examples

We propose a system that allows the user to design a continuous flow animation starting from a still fluid image. The basic idea is to apply the fluid motion extracted from a video example to the target image. The system first decomposes the video example into three components, an average image, a flow field and residuals. The user then specifies equivalent information over the target image. The user manually paints the rough flow field, and the system automatically refines it using the estimated gradients of the target image. The user semi‐automatically transfers the residuals onto the target image. The system then approximates the average image and synthesizes an animation on the target image by adding the transferred residuals and warping them according to the user‐specified flow field. Finally, the system adjusts the appearance of the resulting animation by applying histogram matching. We designed animations of various pictures, such as rivers, waterfalls, fires, and smoke.

3D modeling of trees from freehand sketches

We will present a user interface for quickly and easily modeling three-dimensional (3D) botanical trees from freehand sketches. The system generates 3D geometry from a two-dimensional (2D) sketch based on the assumption that trees spread their branches uniformly. Several editing operations are implemented, such as adding, cutting, and erasing branches. Our system also predicts, and generates, branches automatically. The user can continue editing a 3D tree by selecting the predicted branches. The interface of our system allows novices to design reasonably natural-looking trees quickly and interactively as compared with the interfaces of rule-based systems designed for expert users (e.g., L-systems).