A general function model of spatial straight line is established according to its linear parametric equation. And a
structured total least squares algorithm for spatial straight line fitting is investigated in this paper, not only taking into
account the errors caused by X, Y, Z three directions and the results impacted by constant columns in the coefficient
matrix, but also considering the repeating elements of the coefficient matrix get the same corrections in different
locations. The example given in this contribution illustrates that the efficiency and feasibility of this algorithm.
Sphere target is an important toolbox in terrestrial laser scanning. With the sphere target, multiple point clouds data
obtained from different views can be transformed into the same coordinate frame. Determination of the sphere target
center is key to complete the task mentioned above. A usual approach to determine the coordinates of the center of the
sphere is the Less Squares (LS) method. In this paper, a new method using Total Least Squares (TLS) to determine the
center of the sphere target is investigated. For the new method, a special model is assumed that the design matrix
contains the linearization, and errors in both the residuals vector and the design matrix can be minimized simultaneously.
Various experiments are conducted using the real point clouds data, and it is shown that the proposed TLS approach
works effectively and achieves better results than the usual LS method.