【摘要】 运用计算机图形图像技术,开发了基于CT图像的集料尺寸三维虚拟测量方法,获得了沥青混合料的精准级配参数。方法分为3个步骤:首先,基于灰度差异阈值检测CT图像中的集料轮廓,完成轮廓的二维图形建模,再基于隶属同一集料的轮廓模型进行图形学蒙皮操作,获得集料的三维模型并计算其体积。其次,开发最小包围盒搜索算法确定集料模型的最小包围盒,并以包围盒的长边方向为集料主轴方向。最后,结合集料在主轴方向上的形状变化特点和过筛振动效应,开发控制平面搜索算法,确定集料过筛的控制平面,从而获得集料的最小过筛尺寸。为了验证该方法测量振动过筛条件下不规则集料尺寸的效果,随机选择了6个集料进行CT扫描,基于此完成了集料的三维实体重构与虚拟测量。结果表明:与试验测量法的结果相比,采用虚拟测量法获得的集料体积与过筛尺寸的最大误差分别为2%和3.44%。基于此方法完成了混合料试件中粗集料的三维重构、过筛尺寸及体积的测量,最终获取了混合料的级配参数。更多还原

【Abstract】 A method for the 3 D virtual measurement of aggregate size is developed based on computed tomography(CT) images using computer graphics and image processing techniques to obtain the highly accurate gradation parameters of asphalt mixture. The methodology consists of 3 steps as follows: First, identify the 2 D outlines of aggregates in CT images based on the threshold of grayscale difference for the 2 D graphical modeling of the outlines, and conduct skinning operations in computer graphics based on the mapping between aggregates and outlines to obtain the 3 D models of aggregates and calculate aggregate volumes. Then, develop an algorithm for searching the minimum bounding box to determine the minimum bounding box of the aggregate model, and identify the long side of the box as the principal axis of the aggregate. Finally, develop the searching algorithm for the control plane to determine and obtain the aggregate sieve size according to the aggregate shape characteristics in the direction of principal axis and sieve shaking effect. Six kinds of aggregates are randomly selected and scanned with CT equipment, 3 D reconstructed and virtually measured to verify the effect of the proposed method on the aggregates of irregular shapes under sieve shaking effect. The result shows that the maximum differences of aggregate volume and sieve size between experimental measurement and virtual measurement are 2% and 3.44% respectively. The coarse aggregates in mixture specimen are reconstructed, their sieve sizes and volumes are measured, thus the gradation of the mixture is obtained.更多还原