This paper examines the problem of geometric constraints
acquisition of a planar motion through a line-geometric ap-
proach. In previous work, we have investigated the problem
of identifying point-geometric constraints associated with a
motion task which is given in a parametric or discrete form.
In this paper, we seek to extend the point-centric approach
to the line-centric approach. The extracted geometric con-
straints can be used directly for determining the type and di-
mensions of a physical device such as mechanical linkage
that generates this constrained motion task.