Real Brush Research Articles

Analysis of the Evolution of Calligraphy Creation Style Combined with Numerical Analysis Methods

Abstract The combination of computer technology and calligraphy art is better applied to people’s daily lives while promoting the popularization and development of calligraphy art. In this paper, the mechanical model of the brush tip is constructed on the basis of the spring-vibrator model according to the relationship between the force and the deformation of the brush tip in the real calligraphy creation and drawing. The projection plane is constructed by the method of mapping, and the two-dimensional brush strokes generated on the projection plane are mapped onto the surface of the three-dimensional model in real-time, and the method of minimally enclosing the sphere of the brush tip is used to solve the normal vector direction of the plane. Finally, the orthographic projection of the contact area between the brush and the plane is taken as the brush stroke, and the real brush stroke is simplified to be fitted by two symmetric B-spline curves. The results show that the maximum value of the relevant parameter of the sine equation in the four simulations of the regular script style is 1.5075, which has the best-fitting effect. After 300 iterations of calligraphic creation style evolution, the style recognizability reaches 24.8. The method feeds back the process of recreating calligraphic style and increases the interactivity of calligraphic creation.

Tracking of Flexible Brush Tip on Real Canvas: Silhouette-Based and Deep Ensemble Network-Based Approaches

Digital painting is a process of creating a digital artwork using modern human-computer interaction technologies. One of the core enabling technologies is the real-time tracking of user's strokes, which is generally supplied by a digital tablet with a stylus. While the digital tablet technology provides highly accurate tracking, the drawing should be done with a rigid stylus on a plastic surface. This sometimes destroys the realism of drawing, such as interaction with the digital tablet cannot provide the feedback of subtle texture, friction of the paper/fabric canvas and tension of soft painting brush. This becomes particularly problematic for traditional painting artists who are trained with and prefer real painting brush and paper/fabric canvas. Thus, the aim of this work is to present an alternative solution where the user's strokes can be tracked even when the actual brush and canvas are used. To this end, we proposed two approaches for digitally tracking the tip of flexible bristles of a soft brush, so that the painting can be created digitally on a computer. The first approach captures the silhouette of deforming bristles using a pair of well-aligned infra-red (IR) cameras, which extracts the tip from the silhouette, and reconstructs the 2D position of the tip. The second approach predicts the brush tip position through a deep ensemble network-based approach where the relationship between the brush tip position and brush handle pose are trained with our novel model comprising of Long-Short Term Memory Autoencoder and 1-D Convolutional Neural Network. The trained model is used to predict the brush tip position in realtime. Both approaches extensively evaluated through multiple tests. Furthermore, our model outperforms the state-of-the-art models.

Research progress on and prospects for virtual brush modeling in digital calligraphy and painting

As the crown of the scholar’s four jewels, the brush has occupied a cherished position in the culture of traditional Chinese painting and calligraphy since its invention. In virtual painting, virtual brush modeling plays the most important role. A powerful virtual brush model can truly reflect the characteristics of a real brush and enhance the reality of virtual painting. By reviewing the state of the art in virtual brush modeling, we summarize the basic principles, merits, and drawbacks of typical modeling methods, and discuss simulation results based on empirical methods and physical methods separately. The influences of brush-paper, paper-ink, and human-computer interactive devices on virtual brush modeling are analyzed briefly. The main challenges and problems in virtual painting are analyzed, and the prospects for research on virtual brush modeling in the future are put forward.

Simulating oriental brush character considered with aerial action of pen tablet

The calligraphy is widely known in the oriental countries and has received art and high evaluation in history. The calligraphy is not only intended as a means of communication but also as a traditional culture that shows the artist using bristles and ink. The artwork is a cooperative process that involves the unique features of an ink painting device. The ink painting is expressed by diffusion, scratchiness and the light and shade. The purposes of this research are the simulation of oriental brush character considered with the aerial action of the pen tablet. Our system expresses the light and shade by changing the ink with the brush tip. In this system, the user attaches a light ink to the whole brush and touches a shading ink only on the tip of brushes. These characteristics are influenced by the pen pressure which is used to measure the ability of given pressure to the paper from a pen. The pen pressure is based to paper from the base of the pen, but the oriental brush pressure can be from the base of the oriental brush to the paper and from the tip of the oriental brush to paper. Consequently, the brush base pressure is the pen tablet pressure and the brush tip pressure is the aerial action of the pen tablet. The necessary information is obtained from pen tablets is XY-coordinate, pressure, direction, and altitude. In addition, the Z-coordinate is acquired using a web camera. Therefore, the distance from the tablet to the pen is measured. This distance is the Z coordinate which is the pressure at the tip of the brush. We express the light and shade by changing the pressure and Z-coordinate by using the droplet model. Additionally, the system reveals scratchiness and diffusion with an oriental brush that is affected by the amount of water and ink. As a result, users are able to write a calligraphy on the tablet with an oriental brush as a real brush and a feeling with a more delicate expression.

Analysis and Detection of Short Circuits in Fractional Horsepower Commutator Machines

An improved mathematical model for transient simulations of commutator machines is presented in this paper. This model can simulate and predict the line current harmonics during healthy and faulty operation conditions. A lumped parameter model that considers every single coil in the stator and rotor as a separate electrical and magnetic circuit is proposed. Self and mutual inductances of the coils are estimated by means of the winding function approach (WFA), accounting for the most relevant space harmonics in the machine air gap. The commutation is modeled by using the real brush width and assuming that the brush-commutator contact resistance is a function uniquely of their contact area, which depends on the armature position. Short circuits between adjacent commutator bars are investigated. It is shown that the model achieves good accuracy, reproducing fairly well the armature current ripple for healthy and faulty operation of the machine.

Numerical Simulation of Three-Dimensional Bristle Bending in Brush Seals

This paper presents a new method for predicting the three-dimensional (3D) bending behavior of bristles in brush seals. The model builds on and addresses shortcomings in an earlier two-dimensional bending model. The work was motivated by the need to develop a general 3D solid mechanical model that can ultimately be incorporated into CFD models of flow and heat transfer through brush seals. The iterative method considered here, which is based on linear beam-bending theory, allows relatively large numbers of bristles to be considered with arbitrary imposed aerodynamic forces. Bristle-to-bristle contacts and deflections are considered, as well as shaft and backing ring contacts. The method also allows arbitrary initial bristle packs and lay-angles to be considered, as well as periodic conditions so that the model represents a sector of a brush seal. Other physically important features, such as the so-called 3D-splay and inclined prop effects, are also taken into account. The method described here has been incorporated into a new computer code called SUBSIS (Surrey University Brush Seal Iterative Simulator). Example results from this code are presented that show the bending behavior of initially hexagonally packed brush seals under model imposed pressure loads acting on the bristle tips. The effects of rotor incursions into the bristle pack, increase of the pressure load, and changes in the lay-angle and Young’s modulus are also shown. The results illustrate the expected bending behavior observed in real brush seals. Procedures for coupling SUBSIS with CFD models are also currently under investigation.

Droplet: A virtual brush model to simulate Chinese calligraphy and painting

This paper proposes a virtual brush model based on droplet operation to simulate Chinese calligraphy and traditional Chinese painting in real time. Two ways of applying droplet model to virtual calligraphy and painting are discussed in detail. The second droplet model is more elaborated and can produce more vivid results while being slightly more time-consuming. The novel feature of the proposed droplet virtual brush model successfully enables the simulation painting system to overcome the poor expressional ability of virtual brush based on particle system and avoids the complex evaluation of physical brush with solid model. The model, derived from the actual calligraphy and painting experience, due to the simplicity of the droplet operation and its powerful expressive ability, considerably improves the performance of the simulation system and maintains painting effect comparable with real brush by supporting special Chinese brush effect such as dry brush, feng and stroke diffusion.

Ignition tests with brush discharges

To study the ignition behaviour of brush discharges a new experimental approach was chosen. With this procedure it is possible to investigate in a reliable way whether pure dusts may be ignited with real brush discharges or not. So far no ignition was observed. The investigations continue with other dusts and the most recent results will be reported.

A method of analysing dynamic properties of direct current machines with regard to the real brush width

In mathematical models of direct curent machines a point contact between the brush and the commutator is usually assumed ignoring the effect of the armature coils short-circuited by the real brush. This paper presents an analysis of d.c. machines taking into account the real width of the brush. The operation of a real brush covering any number of commutator bars was modelled using ap system of point brushes (the first of which represents the entering edge and thep brush stands for the leaving edge of the real brush) connected together short-circuiting thereby a part of the armature coil. General equations for the machine incorporating this model of the real brush were presented. The chosen transients of the investigated motor were presented and the conclusions formulated on the basis of the proposed model and the numerical calculation carried out.