Fabian Di Fiore

From dust till drawn: A real-time bidirectional pastel simulation

We present a system for drawing pastel media in real-time as an effective alternative to most existing digital solutions that basically allow for drawing arbitrary strokes in a particular style. Our approach is focused on the simulation of the natural material itself and on its interaction with the drawing surface and the drawing tool.Upon free-form drawing, a bidirectional transfer of pigment takes place. In one direction, the paper surface is dusted with new pigment particles broken off the tip (i.e., the end of the drawing tool). A large part of these particles will be deposited or blended together with previously deposited ones whereas the remainder does not contribute to the drawing and is blown off. On the other hand, a certain amount of previously deposited pigment is scraped off and picked up again soiling the tip. This is noticeable in the next strokes to be drawn. Furthermore, both the tip and the paper surface are subject to weathering depending on the exerted pressure and friction of the drawing tool, and the bumpiness of the paper. As a result, the paper surface becomes slightly damaged, limiting the deposition of new pigment. The tip, on the other hand, becomes blunt making new strokes wider.From a stylistic point of view, similarly to traditional drawings our results convey the artists’ characteristics (e.g., the way of wielding the brush, skillfulness, feeling for the medium). Therefore, we believe that our system allows an artist to create realistically looking pastel images without losing his/her personal touch.We present a system for drawing pastel media in real-time as an effective alternative to most existing digital solutions that basically allow for drawing arbitrary strokes in a particular style. Our approach is focused on the simulation of the natural material itself and on its interaction with the drawing surface and the drawing tool. Upon free-form drawing, a bidirectional transfer of pigment takes place. In one direction, the paper surface is dusted with new pigment particles broken off the tip (i.e., the end of the drawing tool). A large part of these particles will be deposited or blended together with previously deposited ones whereas the remainder does not contribute to the drawing and is blown off. On the other hand, a certain amount of previously deposited pigment is scraped off and picked up again soiling the tip. This is noticeable in the next strokes to be drawn. Furthermore, both the tip and the paper surface are subject to weathering depending on the exerted pressure and friction of the drawing tool, and the bumpiness of the paper. As a result, the paper surface becomes slightly damaged, limiting the deposition of new pigment. The tip, on the other hand, becomes blunt making new strokes wider. From a stylistic point of view, similarly to traditional drawings our results convey the artists’ characteristics (e.g., the way of wielding the brush, skillfulness, feeling for the medium). Therefore, we believe that our system allows an artist to create realistically looking pastel images without losing his/her personal touch.

Sketching with a low-latency electronic ink drawing tablet

Drawing on paper is an experience which is still unmatched by any input device for drawing into a computer in terms of accuracy, dexterity and general pleasantness of use. This paper describes a paper-like drawing tablet which uses electronic ink as its output medium with stylus-based touchpanel input. The device mimics the experience of drawing in a manner which can be adjusted to approach the feel of different kinds of paper. We discuss further some basic issues which need to be addressed in managing interfacing to such a device, specifically the avoidance of the legacy of mouse-oriented point-and-click interfaces which have influenced GUI design for so long. We see a sketch-based model for interaction, based on free-form curve drawing, as being the way forward but new interaction models are required. The tablet is initially intended to serve as an input-device for cartoon drawing and editing, so the product of any sketching process has to be presented to the rest of the animation data-path in terms of a conventional curve model, here Bézier chains. We discuss models for achieving this without having to resort to legacy curve-editing techniques which have no counterpart in drawing on paper or in the repertoire of the traditional animator. Potential uses of these interaction techniques go well beyond supporting the cartoon drawing application.

Uniting cartoon textures with computer assisted animation

We present a novel method to create perpetual animations from a small set of given keyframes. Existing approaches either are limited to re-sequencing large amounts of existing image/video data, or to interpolating vector based drawings.Our approach benefits from several ideas and techniques from video textures, computer-assisted animation and motion graphs. It combines the re-sequencing of existing material with the automatic generation of new data. Furthermore, the animator can interfere with the animation process at each arbitrary moment.First, a given set of keyframes is used to automatically generate a set of in-betweens. The amount of in-betweens required, depends on a distance metric preventing possible visual discontinuities. Next, an optimised cost graph is derived from the generated frames, indicating for all keyframes how many steps are required to travel from one keyframe to another. Finally, by rearranging the generated sets of in-betweens according to the cost graph, new animations can be synthesised from the generated data.The resulting animations are smooth, broader than the input data and require no postprocessing.

Dip - it: digital infrared painting on an interactive table

In this paper we report on our work to develop a novel input technique for a digital paint system. Using a brush with infrared (IR) light emitting fibers, we were able to create a natural paint interface on an interactive table. This IR-brush adds two important properties to our paint environment: haptic feedback and an accurate brush footprint. The modified brush approaches the haptic feedback of the traditional paint brush. The use of IR-light in the brush enables tracking the contact area of the brush on the interactive table. Informal usability tests show that our digital paint environment offers an intuitive interface and contributes to an enhanced user experience in digital painting.

A ray density estimation approach to take into account environment illumination in plant growth simulation

Light interaction is one of the most important factors in developing realistic plant models. Plants react to received illumination by bending branches, adapting their growth rate, orienting leaves and flowers, producing larger or smaller leaves, etc. In this paper, we present a novel approach to simulate plant growth as a response to environment illumination. The basic idea of our algorithm is to simulate light transport in the environment in which plants grow by tracing light particles originating from light sources. Both intensity and mean direction of incident illumination are determined easily. This is based on a ray density estimation of the environment illumination by means of a predominant illumination direction. An adaptive spatial data structure is used to store the rays along which light particles travel in space. This data structure allows efficient calculation of ray density at locations where the algorithm needs to query incident illumination. Our approach takes into account both direct and indirect illumination and is an algorithm that is both flexible and accurate. It is easy to implement and more general illumination models can be incorporated in a straightforward manner. Furthermore, using a non-uniform, adaptive data structure for storing the rays, calculation time and storage requirements are kept within reasonable limits.

Conveying Emotions through Facially Animated Avatars in Networked Virtual Environments

In this paper, our objective is to facilitate the way in which emotion is conveyed through avatars in virtual environments. The established way of achieving this includes the end-user having to manually select his/her emotional state through a text base interface (using emoticons and/or keywords) and applying these pre-defined emotional states on avatars. In contrast to this rather trivial solution, we envisage a system that enables automatic extraction of emotion-related metadata from a video stream, most often originating from a webcam. Contrary to the seemingly trivial solution of sending entire video streams -- which is an optimal solution but often prohibitive in terms of bandwidth usage -- this metadata extraction process enables the system to be deployed in large-scale environments, as the bandwidth required for the communication channel is severely limited.

Highly stylised animation

In this paper we argue for our NPAR system as an effective 2D alternative to most NPR research, which is focused on frame coherent stylised rendering of 3D models. Our approach gives a highly stylised look to images without the support of 3D models. Nevertheless, they still behave as though they are animated by drawing, which they are.First, a stylised brush tool is used to freely draw extreme poses of characters. Each character is built of 2D drawn brush strokes which are manually grouped into layers. Each layer is assigned its place in a drawing hierarchy called a hierarchical display model (HDM). Next, multiple HDMs are created for the same character, each corresponding to a specific view. A collection of HDMs essentially reintroduces some correspondence information to the 2D drawings needed for inbetweening and, in effect, eliminates the need for a true 3D model.Once the models are composed the animator starts by defining keyframes from extreme poses in time. Next, brush stroke trajectories defined by the keyframe HDMs are inbetweened automatically across intermediate frames. Finally, each HDM of each generated inbetween frame is traversed and all elements are drawn one on another from back to front.Our techniques support highly rendered styles which are particularly difficult to animate by traditional means including the ‘airbrushed’, scraperboard, watercolour, Gouache, ‘ink-wash’, pastel, and the ‘crayon’ styles. In addition, we describe the data path to be followed to create highly stylised animations by incorporating real footage.We believe our system offers a new fresh perspective on computer-aided animation production and associated tools.

Physically-based driven tree animations

Simulating dynamic natural wind effects on trees remains a challenging task in Computer Graphics. From an animators point of view it is a cumbersome and tedious task to create this effect due to the complexity of the tree shape, the numerous protruding branches and the wide variety of foliage. In this paper we present a novel method to create controllable animations of trees. Our approach borrows from several ideas from video textures, computer-assisted animation and motion graphs. It combines re-sequencing of existing material with the automatic generation of new data. Furthermore, the animator can direct the animation at each arbitrary moment using a goal based motion algorithm. First, a small set of motion data is gathered from a physically-based driven tree animation. Next, an optimised motion graph is constructed from the acquired data indicating all possible transitions from one tree pose to another. By creating in-between frames for all pairs of keyframes we ensure smooth transitions. Finally, by walking on the motion graph new non-identical animations are synthesised. The resulting animations are smooth, controllable by the animator and suitable for different production targets including 3D virtual environments (e.g., games) and 2D stylised animation.

Multimodal Interaction in a Collaborative Virtual Brainstorming Environment

In this paper we present our work in setting up a collaborative virtual environment (CVE) framework which is built to support collaborative creative meetings for geographically dispersed participants. Similar to real life, we rely on the use of quick drawings or sketches as a means of communication to convey new ideas, thoughts or other meta-data to other individuals. Furthermore, we concentrate on facilitating the (collaborative) interaction process through the use of four modalities. The first modality is direct manipulation, which is suit-able for direct interaction with the networked environment. Secondly, we look at interaction through gesturing symbols in order not to distract the user’s attention from the meeting. As a third modality we consider interaction through menu and widget manipulation. A fourth modality is established by a camera interface.We expect that the combination of the intuitive interface and the real-time visualisation of the virtual environment leads to a better understanding and realisation of one’s ideas in an early phase of the cooperation.

A virtual interactive community platform supporting education for long-term sick children

Analysis of existing iCT-based solutions for the education of long-term ill children reveal several weaknesses with respect to social and cooperative involvement, cost of development, and mobility issues. We present a scalable and affordable solution that supports both the social needs and learning process of these children. An educational platform was created based on the concepts of 3D networked virtual environments and Virtual interactive Communities. in this work we describe the system architecture, network setup and protocols, and how we implemented the educational support. Our solution incorporates innovative hardware, software and connectivity features, set in a user friendly user interface based on networking and 3D technologies. it helps to establish high quality involvement of the long-term sick children in a communication based scenario between the place where the child stays/has been moved and their original classroom learning setting.