含孤立物体场景的高速、高密度三维面形采集

High-speed and Dense 3D Shape Capture of Scene Consisting of Spatially Isolated Objects

提出了一种用于采集含空间孤立物体场景的高速、高密度三维面形采集方法。该方法将三幅图案高速投影到被测物体上并同步采集图像,从而实现场景三维形貌及纹理的高速记录。其中两幅图案是互相具有π相移的正弦条纹,采用傅里叶变换法求解变形条纹相位。将拍摄到的两幅变形条纹图相加可得到物体表面纹理。另一幅图案用来确定条纹级次,实现绝对相位测量,解决高速形貌采集中孤立物体相位展开难题。它由一系列宽度与正弦条纹周期相同的竖条构成,采用三种灰度对竖条编码。每个竖条由单一灰度或两种在竖直方向上周期性分布的灰度构成,这样可编6个码。将竖条按由这些码构成的伪随机序列排列,得到编码图案。测量时,对拍摄的编码图案解码,通过子序列匹配来确定对应正弦条纹的级次。设计了采用DLP投影仪及高速摄像机的高速测量系统。采用提出的方法实现了640×480分辨率下每秒60帧和320×240分辨率下每秒120帧的三维形貌及纹理采集。

A method for capturing dense 3D shape of scene consists of spatially isolated objects with high-speed is proposed.In this method,three patterns are projected onto objects and the deformed patterns are captured at the same time to obtain their 3D shape and texture.The two patterns are phase shifting sinusoidal fringe pattern.The phase distribution of deformed fringe pattern is obtained with Fourier transform.The texture of objects is obtained by adding these two deformed fringe patterns.Another pattern is used for identifying the order of fringe.Then,absolute phase is obtained and phase of isolated objects can be unwrapped as well.The pattern consists of several vertical slits with width the same as the period of sinusoidal fringe pattern.The slits are coded with three gray levels.A slit consists of one gray level or two gray level distributed periodically.So,six codes are obtained.The slits are arranged according to a pseudorandom sequence consisting of these codes.The order of fringe pattern is determined through subsequence matching.A high-speed capture system was constructed with a modified DLP projector,which can project patterns at 360 fps,and a high-speed camera.The 3D shape and texture capture speed of 60 fps with resolution of 640×480 points and that of 120 fps with resolution of 320×240 points was archived in experiment.