Videometrics Measurement for Dynamic Topography of Large Flexible Cable Net Based on Tiny Light Spot Markers

Background:: Traditional videometric method can not be used in the measurement of large flexible cable-net structure for its large overall size and small partial size. Objective: A videometrics technique was proposed in this work to measure the topography and deformation of a large cable net structure. Methods: Tiny spots with high brightness (and large gray gradient) are used to mark the cable net nodes. By arranging the imaging light path properly, the light spot markers can be enlarged and accurately identified in the captured images. Results: The relationship between the imaging parameters and the gray distribution of the light spot markers were derived and verified. And a topographical measurement experiment of a cable net structure was carried out with the proposed videometrics technique. Conclusions: The topography/deformation of the cable net can be measured with tiny-light spot markers, and the effectiveness and robustness of the technique on topography and deformation measurement of large cable-net structures are demonstrated.