Zhihong Mao

SUSAN structure preserving filtering for mesh denoising

Motivated by the impressive effect of the SUSAN operator for low level image processing and its usage simplicity, we extend it to denoise the 3D mesh. We use the angle between the normals on the surface to determine the SUSAN area; each point has associated itself with the SUSAN area that is has a similar continuity feature to the point. The SUSAN area avoids the feature to be taken as noise effectively, so the SUSAN operator gives the maximal number of suitable neighbors with which to take an average, whilst no neighbors from unrelated regions are involved. Thus, the entire structure can be preserved. We also extend the SUSAN operator to two-ring neighbors by a squared umbrella-operator to improve the surface smoothness with little loss of detailed features. Details of the SUSAN structure preserving noise reduction algorithm are discussed along with the test results in this paper.

Improvement construction for planar g2 transition curve between two separated circles

In this paper, we use the undetermined coefficient method to find a desirable pair of cubic Bezier spirals and a desirable pair of quintic PH spirals to generate planar G2 transition curve between two separated circles. The G2 transition curve can be gotten by the rooting formula, which simplifies the computation, and the ratio of two radii has no restriction, which extends the application area.

A modified nielson's side-vertex triangular mesh interpolation scheme

There are currently many methods for local triangular mesh interpolation that interpolates three end points and corresponding normal vectors of each input triangle to construct curved patches. With the curved patches we can eliminate the mismatch between the smoothness of the shading and the non-smoothness of the geometry that is particularly visible at silhouettes, showing as non-smooth edge junctions at the silhouettes vertices. In this paper we modify Nielsons side-vertex scheme to propose a hybrid interpolation scheme that integrates triangular mesh interpolation with subdivision technique. Using this scheme we can get curved patches with relatively good shape to improve the surface quality with little computation cost. Meanwhile we use adaptive normal vectors interpolation to achieve an efficient and qualitatively improved visible result for shading.

Curvature monotony condition for rational quadratic b-spline curves

The monotone curvature condition for rational quadratic B-spline curves is studied in this paper. At first, we present the necessary and sufficient conditions of monotone curvature for the uniform rational quadratic B-spline segment and we compare it to the curvature condition of rational quadratic Bezier curve. Then, we give the sufficient condition of monotone curvature for the nonuniform rational quadratic B-spline segment. At last, we obtain the condition of monotone curvature for general rational quadratic B-spline curves with any number of control points.

Feature sensitive hole filling with crest lines

Feature sensitive hole filling is important for many computer graphics and geometric modeling applications. In this paper, we address the problem of reconstructing the salient features when filling holes in mesh. It respects fine shape features and works well on various types of shapes, including natural mesh and mechanical parts. For representing salient surface features, we adopt crest lines. The connectivity of the hole including the lost crest lines are decided by triangulation and region growing. The geometric position of the vertices and crest points in the hole are resolved by using a least-squares problem.

G 1 continuity triangular patches interpolation based on PN triangles

There are currently many methods for triangular local interpolation: Given triangular meshes P in three dimension space, the given flat triangles are based only on the three vertices and three normal vectors, or PN triangles, construct a smooth surface that interpolates the vertices of P. In this paper a completely local interpolation scheme is presented to guarantee to join patches G1 continuously around boundary curves of each PN triangle.

Digital repair research on archeological relics

In this paper, we present a digital repair method for archeological relics with some vacant areas. We first use the simple method to find the neighboring area which influences the shape of the vacant area. Then we construct the bi-cubic Bezier spline surface to interpolate given points in the influencing area. Re-sampling points on the bi-cubic Bezier spline surface, we can use triangle meshes to repair vacant areas. The advantage of this method is that the repaired area can smoothly be patched with other parts of archeological relics and it can keep the real shape of vacant areas.

A collaborative design environment

This paper presents a collaborative virtual design environment based on the globally shared product model conforming to STEP Standard. The platform provides an integration environment and changes paradigms between I_DEAS, Smarteam (PDM software) and Conceptual Innovation Design System (CIDS). The platform is illustrated for sugarcane harvester design analysis as an example, and provides a collaborative intelligent environment for the design of products, aiming at integrating people, process and data in the product development.