An Implement Of 3D Face Reconstruction Based On 3DMM

Due to the increasing requirement in commercial and legal fields,3D face reconstruction has become one of the most popular research area in computer vision.Face modeling is widely used in face recognition,3D animated films and games, physics and judicature. However, with the development of 3D face recognition, advanced face reconstruction technology is required, two specific development is to increase efficiency and automation level. It is also a fast-developing area. The currently popular technologies include laser scanning, structure light,3DMM.Technology such as laser scanning has high accuracy for detail description but processing equipments are too expensive for dissemination, no mention the difficult operation and large volume. As a result it can not be used in research and daily life. A new method called 3DMM was proposed by Blanz and Vetter recently. Its advantages include high automation and reality level.This method is based on the fact human face can be modeled by linear space, so constructing a group of basis-faces, solving it by optimization thus rebuilding the model of other people's face is possible.In this paper, the BJUT 3D face database of Beijing University is utilized to construct the three-dimensional basis-faces. The 3D face database data were accumulated by cyberware laser scanner. Because of size differences among hu-man faces, even the feature points(such as eyes, mouth,profile) are difficult to coordinate not to mention the three-dimensional vertex, so pre-processing is necessary in order to achieve well corresponding dense faces models ini- tially. Since the three-dimensional structure of people faces are very complex, Firstly, the three-dimensional data were projected onto two-dimensional plane through cylindrical coordinates parameter to simplify calculation. According to the following formula, the 3D coordinates(X, Y, Z)can be transformed into cylindrical(h, r,φ):then 2D faces were divided based on facial features points(such as eyes, mouth, ears, etc). In this paper it was divided into 36 areas. After that faces had reached regional correspondence but the points within each area are not. Therefore, they can be interpolated: vj,kâ†'(new)=vj,Preâ†'(temp)* (1-Δr)+vfolâ†'(ori)*Δrthen the 3D data can be obtained from the formulae above and the faces are densely corresponding. Followed the mentioned instruction all the faces in the BJUT 3D Face Database were processed then basis-faces were constructed.Next step is defining the cost equation:Shape Prior:A minimum problem was established through the shape information:the database stored information of 500 faces,so n=500.Landmark:Landmark(li,pi)contains 3D coordinate li and 2D coordinate pi, and the goal is to diminish the distance between the projected point from 3D faces and 2D points. Color Difference Cost:color difference cost means the color difference between two correspond-ing points of two-dimensional images. Several points are selected from the three-dimensional model and projected to two-dimensional image according to demarcation of camera. Based on these color information, cost function can be obtained.Thus the cost function is:Which can be solved by Levenberg-Marquardt method.