Catálogo de publicaciones - libros

Panoramic image stitching used to create virtual environments for many applications is crucial for IBR. In this paper, we introduce a four-step algorithm based on SIFT features which makes some improvements on large exposure difference, large scene motion or other misregistrations when stitching panoramic images. We introduce a new method that is to add the adjacent images according to a weight function to eliminate the seam in the transition region. As a result, we apply the panoramic image to a computer game to enhance the reality of the game environment. Through lots of analyses and experiments we find that our method is simple and effective. Because this method is not sensitive to ordering, orientation, scaling and illumination, its stitching precision is much higher than many other methods.

The sub-block-based image retrieval method utilizes global and local image features to retrieve trademarks through separating individual an images into some blocks. This paper proposes a sub-block-based trademark image retrieval algorithm under the polar coordinate system. Experiment results show that our algorithm can keep excellent invariance in image translation, scaling and rotation and the retrieved results can satisfy human visual perception very well.

This paper describes a new framework for image composition according to the blurring effect bred by changing depth of field from the target images. The framework involves two stages: a , in which the target image, with one part of the image purported to be “further” and another part “near”, is presented as “learning data” and the learned filter is applied to some objects in source image; and a , in which those blurred objects of source image are composed into the “further” part of the target image. The framework is based on a simple multiscale Gaussian filter, inspired primarily by recent results in texture synthesis and image editing.

Many natural phenomena usually appear in the scenes of movies. They are characterized by color changing smoothly following the time’s advancement, e.g. day breaking, leaves’ resurgence, foliage greening from yellow or yellowing from green. They are difficult to be captured wholly because of the long time span. Traditional methods for making these types of scenes are inefficient or makeshifts.

In this paper, we propose a semi-automatic temporal color morphing technique for the simulation of smooth color-changing phenomena. Our temporal color morphing method is based on histogram manipulation—histogram warping and histogram-based color transformation. For the simplicity of the calculation, we convert the input of the source sequence and target image to color space. This way we split the three-dimensional problem to three one-dimensional problems. The coordinates are quantized in space with a limited error condition. For customization of the results by the user, we introduce a timing mechanism for controlling the velocities of color morphing. Finally, we apply our temporal color morphing technique to the video clips of several representative natural phenomena to demonstrate the effectiveness of our method.

Highly detailed models are becoming commonplace in computer graphics. Such models are often represented as triangle meshes, challenging rendering performance, transmission bandwidth, and storage capacities. This paper proposes a new scheme for constructing progressive meshes with adaptive subdivision. Besides, we introduce half-edge collapse simplification and present a new way to calculate error distance. Some experimental results show that our proposed method works well on various meshes.

One of the most exciting aspects of shape modeling is the development of new algorithms and methods to create unusual, interesting and aesthetically pleasing shapes. In this paper, we present an interactive modeling system for generating freeform surfaces using a 2D user interface. In this paper, we firstly interpret the given 2D curve to be the projection of the 3D curve that has the minimum curvature. Then we propose a topology-consistent strategy to trace the simple faces on the interconnecting 3D curves. By using the face tracing algorithm, our system can identify the 3D surfaces automatically. After obtaining the boundary curves for the faces, we apply triangulation on these faces. Finally, the shape of the triangule surface mesh that follows the 3D boundary curves is computed by using harmonic interpolation. Solving Laplace’s equations, we are able to construct simple and conceptual 3D models interactively. Although the incorporation of topological manipulation will introduce many new(and interesting) design problems that cannot be addressed in this paper, we show that automatically generated models are both beneficial and feasible.

A new dynamic LOD system is recently proposed to represent fairly large artificial terrains using hierarchical triangular patches[5]. Its mesh structure is unique from other conventional methods because it is designed to reduce the total number of draw primitive calls in a frame rather than the number of primitives. Another distinctive feature is its no-triangulation during the mesh adaptation by using its hierarchical layers and pre-constructed matching blocks. The purpose of the paper is to explain its implementation issues to make the new approach more understandable. Some of optimization issues are also discussed for better implementations.

In computer graphics, methods for mesh simplification are common. However, most of them focus on static meshes, only few works have been proposed for simplifying deforming surfaces. In this paper, we propose a new method for the multiresolution representation of time-varying meshes based on deformation area and feature preservation. Our method uses the famous QEM (quadric error metric) as our basic metric. The idea is to modify the edge collapse cost by adding the deformation and sharp feature weight to the aggregated quadrics errors when computing the unified edge contraction sequence, then adjust this sequence slightly for each frame to get a minimum geometry distortion. Our approach is fast, easy to implement, and as a result good quality dynamic approximations with well-preserved fine details can be generated at any given frame.

Besides spatial elements, their spatial configuration is an important factor affecting urban image. In practice of urban planning, good designers do thoroughly consider goals of urban design and constraints of urban planning. In this paper taking the layout problems of a residential zone as background, a framework of procedural modeling and a constrained layout optimization approach is presented to simulate the design procedure of human. The approach represents design goals as cost function subject to planning constraints. We can obtain the design plan by minimizing the objective function. During optimization, we adopt heuristic algorithm to get solutions efficiently for elements layout. Experiments show this approach is able to achieve similar design of residential zone to human work, by using less human resources.

In this paper as one example of a new edutainment system, we propose an “Interactive Folktale System,” which makes it possible for people, especially children, to enjoy folktales in various ways. They can appreciate the generation of original tales and variations. Also they can interact with the story by communicating with its characters or by playing one of the characters. Moreover, they can easily create a new folktale by changing the original story or by describing a new story.