Blast Physics: Photogrammetry

Photogrammetry means 'making measurements using photography'. JASCO uses numerous high-speed photogrammetric techniques to measure the properties of blast waves in air. In-house software is used to calculate three-dimensional positions from measurements made on two-dimensional film images of moving smoke trails and shock fronts, and solid objects such as target fragments.

JASCO's collection of in-house software for photogrammetric transformations can be applied to any photographic record, not only to films of explosions. If you have any photogrammetric needs, please contact us.

JASCO uses cinematic photogrammetry to determine three-dimensional trajectories for analysis. Velocities and accelerations are calculated, for example. Particle trajectory analysis of smoke tracer motions is used to determine the physical properties of blast waves. The motions of solid objects in blast waves are also measured.

Cinematic photogrammetry is used to measure the distortions of structures in blast waves. For example, the shape of the tall cantilever shown above was examined in a sequences of film frames and the elastic and plastic modes of bending studied. After the explosion the section of cantilever above ground remained straight and appeared to have bent only at its base, but during the blast it was seen to bend in an oscillating whip-like manner.

JASCO uses cinematic photogrammetry to measure motions other than those in blast waves. For example, the splattering of blood after being impacted by a fast-moving object has been studied for forensic purposes.