research articles

Müller, S., and Schödl, A.
A Smart Algorithm for Column Chart Labeling.
Proceedings of the 5th International Symposium on Smart Graphics, LNCS, Springer-Verlag, 2005.

This paper presents a smart algorithm for labeling column charts and their derivatives. To efficiently solve the problem, we separate it into two sub-problems. We first present a geometric algorithm to solve the problem of finding a good labeling for the labels of a single column, given that some other columns have already been labeled. We then present a strategy for finding a good order in which columns should be labeled, which repeatedly uses the first algorithm for some limited lookahead. The presented algorithm is being used in a commercial product to label charts, and has shown in practice to produce satisfactory results.

column chart labeling article

Kwatra, V., Schödl, A., Essa, I., Turk, G., and Bobick, A.
Graphcut Textures: Image and Video Synthesis Using Graph Cuts.
Proceedings of SIGGRAPH 2003, 2003.

In this paper we introduce a new algorithm for image and video texture synthesis. In our approach, patch regions from a sample image or video are transformed and copied to the output and then stitched together along optimal seams to generate a new (and typically larger) output. In contrast to other techniques, the size of the patch is not chosen a-priori, but instead a graph cut technique is used to determine the optimal patch region for any given offset between the input and output texture. Unlike dynamic programming, our graph cut technique for seam optimization is applicable in any dimension. We specifically explore it in 2D and 3D to perform video texture synthesis in addition to regular image synthesis.

We present approximative offset search techniques that work well in conjunction with the presented patch size optimization. We show results for synthesizing regular, random, and natural images and videos. We also demonstrate how this method can be used to interactively merge different images to generate new scenes.

graphcut article (Lo-Res, 3.3 Mb)

graphcut article (Hi-Res, 23.2 Mb)

Schödl, A., Essa, I.
Controlled Animation of Video Sprites.
Proceedings of the First ACM Symposium on Computer Animation, San Antonio, TX, USA, July 2002.

In this paper we present a new approach for generating controlled animations of video sprites. Video sprites are animations created by rearranging recorded video frames of a moving object. With our technique, the user can specify animations using a flexible cost function, which is automatically optimized by repeated replacement of video sprite subsequences.

We also show a fast technique to compute video sprite transitions and a simple algorithm to correct for perspective effects in the input footage. We use our techniques to create character animations of animals, which are difficult both to train in the real world and to animate as a 3D model.

video sprites article (10.2 Mb)

Schödl, A., Szeliski, R., Salesin, D.H., and Essa, I.
Video Textures.
Proceedings of SIGGRAPH 2000, 2000.

This paper introduces a new type of medium, called a video texture, which has qualities somewhere between those of a photograph and a video. A video texture provides a continuous infinitely varying stream of images. While the individual frames of a video texture may be repeated from time to time, the video sequence as a whole is never repeated exactly. Video textures can be used in place of digital photos to infuse a static image with dynamic qualities and explicit action. We present techniques for analyzing a video clip to extract its structure, and for synthesizing a new, similar looking video of arbitrary length.

We combine video textures with view morphing techniques to obtain 3D video textures. We also introduce videobased animation, in which the synthesis of video textures can be guided by a user through high-level interactive controls. Applications of video textures and their extensions include the display of dynamic scenes on web pages, the creation of dynamic backdrops for special effects and games, and the interactive control of video-based animation.

video textures article