3D Shape Measurement For Dental Restoration Based On The Color Structured Light

How to reconstruct 3D profile of the teeth quickly and accurately is the vital part of digital dental restoration.Although the silicon rubber impression technique has occurred in the last century and can retrieve the 3D model of the teeth in high precision,comparing with the non-contacting measurement,this method is time-consuming and complex.In order to satisfy the requirement of the speed and precision in application,this paper proposes a novel optical metrology based on the colorful structured light.This paper encodes the phase information in the three channels and utilizes stereo vision system to reconstruct the 3D shape of the teeth.The main techniques are illustrated as follows.(1)As patients' teeth have different colors which will disturb the color information,this paper elaborates the principle of illumination and reflection of the optical wave and why the color information will distort during the propagation.Besides,this paper establishes a mathematical model to rectify the color based on the principle colors and secondary colors.(2)When reconstructing the 3D model based on the colorfully structured light,classifying the colors and segmenting them accurately is a significant part.This paper proposes an approach to recognize the color based on the HSI color model,and establishes a hue transition model to analyze the hue component in the color edge.According to the hue component,the sub-pixel edges can be obtained and can be further applied to reconstructing the sparse 3D model.(3)In order to obtain high-quality dense 3D point cloud of the teeth,the paper encodes the phase information in three color channels in the middle of color stripes.After transforming the color pattern to the HSI color model,the wrapped phase information can be retrieved.Combing with the sequence of color stripes,the wrapped phase converts to unwrapped information,which is applied to retrieve dense 3D point cloud of the teeth.(4)In order to improve the robustness and stability of the reconstruction method,this paper proposes a two-step approach to eliminate the non-linear gamma of the projector and color crosstalk of CCD.Then,the noises caused by these distractions are alleviated significantly.In conclusion,the approach proposed in this paper can obtain the 3D model of object,which can be applied to dental restoration.