Video Analysis

• Video should be in line with the correct plane of movement
• Multiple cameras are required to view all planes of movement
• Camera positioning minimises perspective error
• Calibration allows video to be scales to real-world coordinates
• Manual Digitising: process used for 3D motion capture using multiple cameras and fixed markers on the body for calibration
• Perspective Error: error caused when viewing angle is not perpendicular to the object
• Perspective error can be reduced by placing the camera as far away as possible to reduce angles
• Pan: movement from left to right
• Tilt: movement up and down
• Roll: rotational movement
• Sampling rate: number of frames sampled in a second (Hz)
• Shutter speed: how long the sensor is open and exposed to light
• Low shutter speed: risk of blur if movement is fast
• High shutter speed: risk of dark images as not enough light let in
• Aperture: amount of light let in and depth of field
• Large aperture = more light = small F number
• Small aperture = less light = large F number = better depth of field
• Gen-locking allows multiple cameras to take synchronised images