Graphical Models and Image Processing最新文献

A method for determining the radial distortion parameters of a camera is presented. The technique is based on the analysis of distorted images of straight lines and does not require the determination of point correspondence between a scene and an image of that scene. The method is described in detail, including information on the line detection method and the optimization procedure used to estimate the distortion parameters. Quantitative and qualitative experimental results using both synthetic and real image data show that the technique is effective.

A two-dimensional binary object can be totally covered by a set of disks. From this follows that any object might be represented by these disks rather than by the pixels. This paper deals with the problem of finding the most efficient version of this representation which is called the minimal set of maximum disks (MSD). The proposed algorithm picks candidate disks from the local maxima in the Euclidean distance transform. Then a relation table for the pixel coverage of these disks is estabished, but only for the border pixels which makes the table size reasonable. Three basic table reduction steps are executed to extract and include necessary disks to MSD while eliminating and excluding the unnecessary disks.

Hybrid curves provide an attractive method for approximating rational Bézier curves by polynomial Bézier curves. In this paper, several methods are provided to estimate the error bounds for the approximation to the moving control point of the hybrid curves. When the given rational Bézier curves satisfies the convergent conditions for moving control point of the hybrid curve, by these methods we can choose a hybrid curve with a certain degree such that the distance between the moving control point and a special point is less than a given error bound ϵ. So the polynomial Bézier curves to approximate the rational Bézier curve can be obtained by replacing the moving control point with the special point.

For a given textured image we define a sequence of graphs {N_s(t)}_s∈I(called MRCG), whereN_s(t) is the number of 4-connected components with size ≥s, for the images thresholded witht. The sequence of graphs are computed in almost linear time complexity, where the input size is the number of pixels of the image, using only integer arithmetic. The MRCG is a multiresolution representation, which is very useful for texture characterization. Its properties as a texture characterizer are analyzed and demonstrated.

In this paper we consider a number of extensions to current adaptive compression methods for color images. One, we use clustering or segmentation procedures to determine self-similar image regions. Two, for each such region we use a Karhunen–Loeve compression method to model the important spatiochromatic information. Three, we employ linear prediction to encode the resultant eigenimages. Finally, comparisons are made with current methods and improvements are demonstrated particularly for low bit-rate coding of color textured images such as those that occur in aerial photography.

Themedial axis transformis a representation of an object which has been shown to be useful in design, interrogation, animation, finite element mesh generation, performance analysis, manufacturing simulation, path planning, and tolerance specification. In this paper, the theory of the medial axis transform for 3-D objects is developed. For objects with piecewiseC²boundaries, relationships between the curvature of the boundary and the position of the medial axis are developed. Forn-dimensional submanifolds of $\text{R}$ⁿwith boundaries which are piecewiseC²and completelyG¹, a deformation retract is set up between each object and its medial axis, which demonstrates that if the object is path connected, then so is its medial axis. Finally, it is proven that path connected polyhedral solids without cavities have path connected medial axes.

In this paper, geometric design problems for rational ruled surfaces are studied. We investigate a line geometric control structure and its connection to the standard tensor product B-spline representation, the use of the Klein model of line space, and algorithms for geometry processing. The main part of the paper is devoted to both classical and “circular” offsets of rational ruled surfaces. These surfaces arise in NC milling. Excluding developable surfaces and, for circular offsets, certain conoidal ruled surfaces, we show that both offset types of rational ruled surfaces are rational. In particular, we describe simple tool paths which are rational quartics.