三维激光扫描系统中目标点云的颜色复原

Color restoration of object surface point cloud in three-dimensional laser scanning system

为建立目标表面的真实彩色三维点云数据模型,以编码标志点作为定位介质,利用目标的无色点云和彩色图像,提出一种三维点云颜色复原方法。在目标附近放置多组编码标志点,用基于激光线的三维扫描设备获取目标无色的三维点云和编码标志点信息;用彩色相机从多视角采集目标及编码标志点的彩色图像,通过Canny边缘检测及亚像素定位算法得到编码标志点的图像坐标;再利用改进的直接线性变换法由编码标志点的世界坐标值及像素坐标值求解出相机相对世界坐标系的位姿矩阵,通过相机成像模型建立点云与彩色图像像元的映射关系;最后,利用插值法计算局部点云的颜色并完成整个点云颜色的融合。采用该方法对多个模型进行了颜色复原实验,彩色三维点云的颜色空间位置偏差小于0.6 mm,重建效率为7.3×104 point/s,彩色三维点云与目标相似度高。该方法可以实现目标彩色三维点云重建,计算精度和效率均能够满足使用需求。

To obtain the real colorful three-dimensional(3-D)point cloud data model of a target surface,a 3-D point cloud color restoration method is proposed.The method uses code points,based on the colorless 3-D point cloud and colorful images of an object,as the location medium.First,multiple code points were placed near the object and thecolorless 3-D point cloud of the object;thereafter,the information of code points was captured by a 3-D scanning device based on a structure laser line.A color camera was then used to capture color images of the target from different perspectives,and then,using canny edge detection and a subpixel localization algorithm,coding point coordinate values in the images were calculated.Later,an improved method of direct linear transformation was used to solve the camera pose matrix in the world coordinate system by coding point world coordinates and pixel coordinates.The corresponding relation between the point cloud and color image pixels was then set up by the camera imaging model.Finally,interpolation was used to calculate the color of the local point cloud,and thus,complete color fusion of the entire point cloud was achieved.In the experiments,the proposed method was adopted to restore the color of multiple point cloud models.The color space position deviation of the color 3-D point cloud is less than 0.6 mm,and the reconstruction efficiency is approximately 73000 point/s.The color 3-D point cloud exhibits high similarity with the targets.Therefore,the method can achieve the goal of color 3-D point cloud reconstruction,and the achieved calculation accuracy and efficiency can satisfy user demands.