High-speed close-range photogrammetry for dynamic shape measurement

We describe and characterize an experimental arrangement to perform shape measurements on a deformable object through dynamic close-range photogrammetry; specifically, an insect in flight. The accuracy of shape measurements in photogrammetry is improved by increasing the number of camera views. In static close-range photogrammetry, one may increase the number of camera views by moving the camera and taking a number of images, or equivalently, by moving the object. In dynamic close-range photogrammetry of rigid objects, one may combine all the camera views from a video sequence. However, in dynamic close-range photogrammetry of a deformable object, the number of camera views is restricted to the number of physical cameras available. The technique described here is to arrange a number of cameras around a measurement volume, illuminated by a laser synchronized to the cameras. The cameras are first calibrated, and then a bundle adjustment is used to determine point positions on the object. In this paper, we first determine the capabilities of the system in static close-range photogrammetry. We then perform a static shape measurement on our dynamic target and compare this with the results of dynamic close-range photogrammetry. The results indicate that high-speed dynamic measurements of the deformation of insect wings during flight should provide adequate resolution to develop an aeroelastic model of a flapping wing.