Coloring 3d Printed Surfaces By Projection-Based Texture Mapping Method

In recent years,with the development of 3D printing technology,the texture coloration technology of printing model has also been developed,such as water transfer technology and heat transfer technology,but the technique of attaching color ink to the visible surface of 3D printing model is not perfect.Based on the technology of projection-based augmented reality,this thesis studies the texture coloration technology of 3D printing model to realize a non-destructive dynamic texture coloring system.The traditional coloration technologies for 3D printing,such as water transfer technology and heat transfer technology,are all attaching color film on the surface of 3D printing objects to achieve the effect of coloring.The color film is not easy to fall off the surface.Compared with the industrial electroplating color method,these coloration technologies perform better,and they are more suitable for 3D printing materials.The disadvantages are also obvious that the algorithms of these coloration technologies are complex and they are invasive to the 3D printing model.In this thesis,we propose a new texture coloration method,with which the coloration is not invasive to the original 3D printing object,and the color image could be projected by the lowcost projector.This proposed method is realized by improving projection-based augmented reality technology.The traditional projection-based augmented reality technology needs to do 3D reconstruction of the room or even the objects.And in order to make the correct size of the image projected,multi projector-camera system should be labeled with complex calibration through the 3D reconstruction.The projection-based augmented reality system proposed in this thesis use 2~3 projectors and a camera model to achieve full coverage of the use of texture rendering system projection.In order to show the different texture in real time,the system also uses the programmable turntable to make the model dynamic rotation to show the dynamic effects of different textures.The system requires user to do a system calibration for multi projector-camera model in advance to get the projector reference matrix.Before projecting texture image,user of the system needs to manually select 2D feature points in image of real model taken by camera and the corresponding 3D feature points image in the virtual model.Then geometric registration algorithm of gray code would automatically calculate the transformation matrix between the real model and virtual model.After that,the texture image could be correctly mapped onto the 3D model through geometric transformation of the texture coordinates by the projector.The experimental results show that the texture coloration technology proposed in this paper can effectively and correctly map the texture onto the 3D printing object.