基于球坐标的植物果实重建

Plant fruit reconstruction based on spherical coordinates

针对植物果实形状特点,提出基于坐标变换的点云快速重建方法。对于生长在茎干上的果实,首先计算茎干方向即果实的中心轴方向,将点云直角坐标转为球坐标,利用中值滤波沿半径方向对点云数据去噪,判断果实的长扁特征,计算果实中心轴的经纬度;然后以果实的中心轴作为球坐标的中心轴再次对原始点云进行坐标变换,进行去噪和填空点处理,最后采用B样条曲面对果实进行重建。本文方法的计算效率高于传统方法的2.5倍以上,随着点云数据量的增加,计算速度可加快几十倍,而且重建结果与实际点云误差小于2.2%。

Aiming at the shape characteristics of plant fruits,a fast method of point cloud reconstruction for plant fruit base on coordinate transformation was proposed.For the fruit growing on the stem,the first step was that the direction of the stem or central axis of the fruit was calculated.First,the point cloud was converted for the space rectangular coordinates to the spherical coordinates and was denoised along the radial direction using median filter.Then,the long flat feature of the fruit need to be judged.Finally,the latitude and longitude of the central axis of the fruit were calculated.The second step was that the original point cloud was converted again for the space rectangular coordinates to the spherical coordinates and the central axis of the fruit was used as the central axis of the spherical coordinate.Then the point clouds were denoised and filled empty points.Finally,the B-spline surface was used to reconstruct the fruit.The calculation efficiency of this method was more than 2.5 times higher than that of the traditional method.With the increase of point cloud data,the calculation speed could be accelerated by dozens of times,and the error between the reconstruction result and the actual point cloud was less than 2.2%.