While each camera view individually suggests that interaction affected the two animals, taken separately they provide conflicting information. 3 shows the paths of the sergestid and fish calculated by the EV3D program for each view. Because of the camera angles, the sergestid appears to dart upward vertically along 2 different diagonals , and the fish actually appears to swim in opposite directions. Any behavioral measurements based on either one of these 2-dimensional views alone would be wrong. 3-D sampling tools are absolutely essential.
Correct lighting is important for subsequent digitization of recorded images.
If lighting is uneven, the threshold level will change from frame to frame because contrast between the target and the background changes and the computer is unable to digitize the target throughout the sequence. Broad-beam lights are essential because the light field must be as even as possible. Cameras on the submersible should be spaced as far apart as possible. Increased separation improves the accuracy of measuring coordinates along the axis perpendicular to the plane of the cameras. When possible, additional cameras should be used to increase the probability of the target remaining in more than one view.