A non-straight sensor array within a gravity field, within a surface and cyclically surrounding a medial axis. The sensor array includes rigid bodies holding gravimetric tilt sensors, the rigid bodies being connected by flexible joints. The flexibility of the joints is constrained to two degrees of freedom. The shape of the path, the surface, and the medial axis are measured in at least two dimensions, using the tilt sensor data and the geometrical constraints of the joints. The cyclical geometry permits simultaneous measurement of lateral and axial deformations in deployments varying from axially vertical to axially horizontal, as well as improved fit of the array to surrounding surfaces. The field of use includes geotechnical measurements of soil and civil structures.