Non-Invasive Model Attitude and Deformation Measurement

A system for high-resolution, real-time (40Hz), non-invasive wind tunnel attitude and deformation measurement is proposed. The system combines projection of structured laser light with photography of the illuminated surface. Photogrammetric techniques are used to obtain the three dimensional shape of the surface. Whereas most structured light systems employ a repeating pattern of lines, the proposed system uses a robust true 2D pattern that is maximally distinct in any small region. This approach captures all the data necessary to determine the relative 3D positions of separated objects or portions of an object with a single pattern and eliminates the need for alignment of multiple patterns projected in sequence, allowing rapid high resolution profile capture. It also facilitates capture of relative positions of separated objects by avoiding the position ambiguities introduced with repeating patterns. Shapes of rapidly moving or deforming objects are captured in a single laser flash, allowing direct measurement of transient structure strain, vibration, or motion. 3D snapshots of wind tunnel models can be acquired in either single-camera or multi-camera mode, with short exposure times, fast frame rates, and high accuracy.