Close Range Photogrammetry for Deformation Measurement

Measuring deformations of steel beams under stress by four cameras tracking the 3D movements of coded targets.

Modern constructional steelwork is characterized by slim structures and production-optimized designs. Plates are often so slim, that they tend to bulge and bend under stress. The Institute for Construction and Design at the University of Stuttgart conducted large-scale experiments at the Materialprüfanstalt MPA in order to determine how accurate the theoretical description of these processes are.

The examined steel beams are too large for a dense deformation tracking solely by local odometers etc. Therefore, we supported this project by implementing and operating a close range photogrammetric measurement setup and evaluation pipeline.

Four industrial IDS uEye provide the images. The cameras are mounted on individual tripods or installed into an aluminum profile frame with a fixed relative orientation, depending on the measured object. Baselines reach from 15cm to about 1.5m. Cables connect the cameras to a laptop directly via USB and indirectly via a microcontroller relay. We developed custom software for the operator to control the cameras. This configuration allowed reaching a deformation accuracy of ca. 0.1mm.

Figure 1: Frames showing the deformation of the outburst experiment. (c)
Figure 1: Frames showing the deformation of the outburst experiment.

Figure 2: Frames showing the deformation of the twist and kink experiment. (c)
Figure 2: Frames showing the deformation of the twist and kink experiment.
Dieses Bild zeigt Schmohl
M.Sc.

Stefan Schmohl

Research Associate

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