Based on the detailed analysis of MC(Marching Cubes)algorithm which is widely used for extracting Iso surface from volume data filed

this paper presents a new method for 3D reconstruction and visualization: directional smooothing and polygonal merging on the extracted iso surface. The directional smoothing method decomposes the Iso surface into a 3D coordinate field and a vector field

and then performs a smoothing process in this vector field. By vector field smoothing

the reconstructed results and the rendred anatomical details are greatly improved. The method of Iso surface merging is analyzed in this paper. According to correct merging principles and threshold value

this method transforms the triangle composed iso surface into polygon composed iso surface

and it can greatly speed up the 3D rendering process without impairing reconstruction fidelity and anatomical details. A modified approach of 3D reconstruction and rendering is presented in this pqper

which can improve the results of 3D reconstruction

and at the same time

speed up the 3D rendering process.