An accurate detection of the radiation field is crucial to 3D conformal radiotherapy (3D-CRT). Automated techniques to detect the field edges on double exposure portal images have previously focused on thresholding techniques. In this paper, we present a new approach based on a curve propagation technique (the Fast Marching method) which proves to be more effective at detecting the radiation fi...

In this paper, we propose to use image pixels for geometry reconstruction with a shape from silhouette approach. We aim at estimating shape and normal for the surface of a single object seen through calibrated images. From the voxel-based shape obtained with the algorithm proposed by R. Szeliski in [18], our main contribution concerns the use of image pixels together with marching cubes for con...

This paper presents a new method for polygonization of implicit surfaces. Our method put emphasis on the shape of triangles of the resulting polygonal mesh. The main advantages of the triangulation presented are simplicity and the stable features that can be used for next expanding. The implementation is not complicated and only the standard data structures are used. This algorithm is based on ...

This paper presents a powerful and general purpose tool designed to extract characteristic lines from 3D images 1. The algorithm, called Marching Lines, is inspired from the Marching Cubes algorithm, which is used to extract iso-value surfaces from 3D images. The Marching Lines algorithm extracts with sub-pixel accuracy the 3D lines corresponding to the intersection of two iso-surfaces from two...

This paper describes the main principles used in the development of the VECTIS mesher. The mesher produces unstructured 3D meshes suitable for Finite Volume Methods. It is based on the Cartesian approach. In contrary to the traditional approaches which use exact shape of boundary faces of cut cells, this mesher employs Marching Cubes method for generation of majority of boundary faces. Only in ...

This paper presents a coupled level-set segmentation of the myocardium of the left ventricle of the heart using a priori information. From a fast marching initialisation, two fronts representing the endocardium and epicardium boundaries of the left ventricle are evolved as the zero level-set of a higher dimension function. We introduce a novel and robust stopping term using both gradient and re...

The existing Fast Marching methods which are used to solve the Eikonal equation use a locally continuous model to estimate the accumulated cost, but a discontinuous (discretized) model for the traveling cost around each grid point. Because the accumulated cost and the traveling (local) cost are treated differently, the estimate of the accumulated cost at any point will vary based on the directi...