Chin-Chen Chang

New approach for static gesture recognition

Static gestures can convey certain meanings and act as specific transitions in dynamic gestures. Therefore, recognizing static gestures is one of the most important aspects of gesture recognition. In this paper, a new approach is presented for recognizing static gestures based on Zernike moments (ZMs) and pseudo-Zernike moments (PZMs). The binary hand silhouette is first accommodated with a minimum bounding circle (MBC). The binary hand silhouette is then decomposed into the finger part and the palm part by morphological operations according to the radius of the MBC. After that, the ZMs & PZMs of the finger part and the palm part with different importance, respectively, are computed based on the center of the MBC. Finally, 1-nearest neighbor techniques are used to perform feature matching between an input feature vector and stored feature vectors for static gesture identification. Results show that the proposed approach performs better than previous methods based on conventional ZMs & PZMs in recognizing static gestures. The proposed technique could be useful in improving the recognition rate, of static gestures.

Feature alignment approach for hand posture recognition based on curvature scale space

One of the most important aspects of gesture recognition is recognizing hand postures. Much research has been devoted to extracting reliable features for hand posture recognition. In this paper, a new feature alignment approach for hand posture recognition based on curvature scale space (CSS) is presented. The basis point for alignment is based on the two-dimensional distribution of a coordinate-peak set of the CSS image instead of on the coordinate with the maximal peak. A convolution operation is performed with the sequence of a coordinate-peak set and a predefined function. The coordinate with the maximal convolution value is designated as a basis point for aligning the CSS features of the hand posture. Results show that the proposed approach performs well in recognizing hand postures. Furthermore, the proposed approach is more accurate than previous methods based on conventional features.

Adaptive multiple sets of CSS features for hand posture recognition

Abstract In this paper, an adaptive feature extraction approach based on curvature scale space (CSS) is presented for translation, scale, and rotation invariant recognition of hand postures. First, hands are segmented from hand posture images into binary silhouettes and then binary hand contours are computed. CSS images are then used to represent the contours of hand postures. In particular, adaptive multiple sets of CSS features are extracted to address the problem of deep concavities in the contours of hand postures. Finally, 1-nearest neighbor techniques are used to perform adaptive multiple sets of CSS feature matching for hand posture identification. Results indicate that the proposed approach performs well in the recognition of hand postures. And, the proposed approach is more accurate than previous methods which were based on conventional features. The proposed technique could be useful in improving the recognition of hand postures.

Synthesizing transition textures on succession patterns

Synthesizing transition textures on succession patterns for displaying visually acceptable terrain is essential to applications such as computer games. In this paper, we exploited the Game of Life model to simulate successions on terrain to show that a good-looking profile can appear quickly and easily. Based on the proposed modified patch-based sampling texture synthesis approach, the basic types of transition textures on a succession pattern can be well synthesized. This method first generates a well-shaped transition cut along the source texture. Next, the feature maps of the source texture and the target texture are used to determine complementary patches from the target texture that will fit well along the sources transition cut. As the experimental results show, only a few input textures are required by our approach to synthesize plenty of tileable transition textures which are useful for obtaining vivid terrain while consuming only a small amount of texture memory.

An improved data hiding approach for polygon meshes

We present an improved technique for data hiding in polygonal meshes, which is based on the work of Bogomjakov et al. (Comput. Graph. Forum 27(2):637–642, 2008). Like their method, we use an arrangement on primitives relative to a reference ordering to embed a message. But instead of directly interpreting the index of a primitive in the reference ordering as the encoded/decoded bits, our method slightly modifies the mapping so that our modification doubles the chance of encoding an additional bit compared to Bogomjakov et al.’s (Comput. Graph. Forum 27(2):637–642, 2008). We illustrate the inefficiency in the original mapping of Bogomjakov et al. (Comput. Graph. Forum 27(2):637–642, 2008) with an intuitive representation using a binary tree.Although both methods have the same minimal and maximal capacities and are both only one bit per primitive less than optimal, our method improves the average capacity up to 0.63 bits per primitive. Our embedding and extraction algorithms are just as simple to implement and just as efficient, O(n), as those of Bogomjakov et al. (Comput. Graph. Forum 27(2):637–642, 2008).

An efficient structure-aware bilateral texture filtering for image smoothing

Photos contain well‐structured and plentiful visual information. Edges are active and expressive stimuli for human visual perception. However, it is hard to separate structure from details because edge strength and object scale are entirely different concepts. This paper proposes a structure‐aware bilateral texture algorithm to remove texture patterns and preserve structures. Our proposed method is simple and fast, as well as effective in removing textures. Instead of patch shift, smaller patches represent pixels located at structure edges, and original patches represent the texture regions. Specifically, this paper also improves joint bilateral filter to preserve small structures. Moreover, a windowed inherent variation is adapted to distinguish textures and structures for detecting structure edges. Finally, the proposed method produces excellent experimental results. These results are compared to some results of previous studies. Besides, structure‐preserving filtering is a critical operation in many image processing applications. Our proposed filter is also demonstrated in many attractive applications, such as seam carving, detail enhancement, artistic rendering, etc.

Inner engraving for the creation of a balanced LEGO sculpture

LEGO is a globally popular toy composed of colorful interlocking plastic bricks that can be assembled in many ways; however, this special feature makes designing a LEGO sculpture particularly challenging. Building a stable sculpture is not easy for a beginner; even an experienced user requires a good deal of time to build one. This paper provides a novel approach to creating a balanced LEGO sculpture for a 3D model in any pose, using centroid adjustment and inner engraving. First, the input 3D model is transformed into a voxel data structure. Next, the model’s centroid is adjusted to an appropriate position using inner engraving to ensure that the model stands stably. A model can stand stably without any struts when the center of mass is moved to the ideal position. Third, voxels are merged into layer-by-layer brick layout assembly instructions. Finally, users will be able to build a LEGO sculpture by following these instructions. The proposed method is demonstrated with a number of LEGO sculptures and the results of the physical experiments are presented.

Special Section on Procedural Modeling: Procedural grape bunch modeling

This paper proposes a grammar-based procedural approach for modeling of grape bunches. A proposed description of the formal rules of an open L-system can be used to model almost all types of grape bunches. When growing a grape bunches, the overall shape for controlling the development is first given by users through the provided user interface, which determines the parameters used for rules. The interaction simulation process then simulates the natural thinning effect between the newborn internode and the existing grape structure via a communication module for the adjustment of the growing directions of branches, twigs and berries during the interpretation of generated string. As experimental results show, our approach is capable of modeling almost all types of grape bunches effectively with realistic visual effects. Also, our approach can be extended to modeling many panicle berry bunches.

PATH PLANNING FOR RACING GAMES

We propose a set of path planning tools including path generator, cost map generator, and path editor for racing games. The user can define the race by providing a racetrack as a 3D model and weights of the devised turn and heuristic functions in our system. Then, the proposed cost map generator automatically generates necessary information of the racetrack including cost map and distance to finish of any position on the race track. Different from the traditional A* problem, in our research the obstacles are dynamic and there are multiple sources and destinations. Our approach generates the path of each racer on the basis of time slots to which the path finding method applies on the fly. To further guarantee the quality of the path, we implement path smoothing using a Gaussian filter and provide an off-line path editor that allows users to edit the path in time-space domain intuitively, flexibly, and effectively. Our tools have been verified in a horse racing game to generate natural racer behaviors, demonstrating realistic and exciting racing.

Adaptive sampling approach for volumetric shadows in dynamic scenes

Ray marching is an important technique to generate volumetric lighting effects. However, it is very expensive for each pixel on the screen, especially in dynamic scenes. The authors propose an adaptive approach to reduce samples for volumetric shadows in the time domain. In dynamic scenes, shadow volumes of moving objects are created and are rasterised to decide pixels that cannot be reused. The authors use a stencil buffer to maintain the information of screen pixels by recomputing or just using the previous information. Experimental results show that the proposed approach is simple to implement. Moreover, compared to the previous method, the proposed approach achieves a specific speedup and maintains similar visual quality.