Figure 2 shows a segment of a circular pipe with r as its radius and (0,0,0) and (0,0,1) as the two ends of its center-line segment. A point cloud (white dots) is captured along the pipe surface with their coordinates represented as (x, y, z), i=1,2....n. What is the error of measurement for the entire point cloud on the pipe surface?
Figure 2: A segment of a circular pipe