Photogrammetry is the technique of analyzing stabilized storm and tornado videos frame-by-frame which-- given frame rate, vortex diameter & circumference (from observed damage path and widths) - particles at various heights tracked per frame, and the observers' exact location relative to the storm-- scientists can calculate and determine important cloud features and debris velocity (speed & direction) with fair precision.

In addition, Project SWIRRL will determine individual debris mass / weight when possible with especially large intact projectiles in order to refine wind speeds and acceleration coefficients with higher precision and accuracy. Calculating actual wind field velocities across a tornado vortex requires high definition video and Force equations. Speed and Velocity isocontours (areas of equal value) can then be determined and graphically overlaid on individual video frames and photographs. 

Photogrammetry and velocimetry become especially useful and important in calculating near-ground wind speeds, debris projectile velocities and correlated damage patterns. Thorough analyses of all these factors will contribute to a greater understanding of the destructive impacts tornados have on homes and structures, whether in populated areas or open fields & farmland.