Showing papers by "Charles R. Dyer published in 1995"

Physically-valid view synthesis by image interpolation

Abstract: Image warping is a popular tool for smoothly transforming one image to another. "Morphing" techniques based on geometric image interpolation create compelling visual effects, but the validity of such transformations has not been established. In particular, does 2D interpolation of two views of the same scene produce a sequence of physically valid in-between views of that scene? We describe a simple image rectification procedure which guarantees that interpolation does in fact produce valid views, under generic assumptions about visibility and the projection process. Towards this end, it is first shown that two basis views are sufficient to predict the appearance of the scene within a specific range of new viewpoints. Second, it is demonstrated that interpolation of the rectified basis images produces exactly this range of views. Finally, it is shown that generating this range of views is a theoretically well-posed problem, requiring neither knowledge of camera positions nor 3D scene reconstruction. A scanline algorithm for view interpolation is presented that requires only four user-provided feature correspondences to produce valid orthographic views. The quality of the resulting images is demonstrated with interpolations of real imagery.

Complete scene structure from four point correspondences

Abstract: A technique is presented for computing 3D scene structure from point and line features in monocular image sequences. Unlike previous methods, the technique guarantees the completeness of the recovered scene, ensuring that every scene feature that is detected in each image is reconstructed. The approach relies on the presence of four or more reference features whose correspondences are known in all the images. Under an orthographic or affine camera model, the parallax of the reference features provides constraints that simplify the recovery of the rest of the visible scene. An efficient recursive algorithm is described that uses a unified framework for point and line features. The algorithm integrates the tasks of feature correspondence and structure recovery, ensuring that all reconstructible features are tracked. In addition, the algorithm is immune to outliers and feature drift, two weaknesses of existing structure from motion techniques. Experimental results are presented for real images. >

Interactivity and the Dimensionality of Data Displays

Abstract: Using mathematical models of data and displays, we illustrate the importance of distinguishing between independent and dependent variables when counting the dimensions of data sets and displays. The number of independent variables occurring as dimensions of a display model is the most important factor determining its information carrying capacity. Independent variables in a display model also require interactive techniques for their implementation, as illustrated by our VIS-AD system and Beshers’ and Feiner’s worlds within worlds technique. Thus interactivity is critical for visually communicating large amounts of information, and the perceptual properties of interaction techniques are an important topic for visualization research.