Figure 1591.
An Object Track or trajectory (schematically shown in the picture) is a sequence of segments that connect successive object positions (P). Each object position has a time value (t) associated at which it was recorded. Distance between two consecutive Points is the length of that segment. Speed is the Segment Length divided by the amount of time elapsed between the two positions. As the segments are one less the number of points, they are by convention associated with the preceding point.
Path is the portion of a track made up of segments from the beginning to the current position. Its Length is the sum of segment distances. Speed is the Length divided by the amount of time elapsed from the beginning to the current position.
Figure 1592.
The length of Acceleration vector |a| is the measure of total force that is acting on an object. Normal Acceleration (aN) is the part of Acceleration vector (a) that is perpendicular to the Velocity vector (v) incoming to the current object position (P). It represents the deviation force. Tangential Acceleration (aT) is the part of Acceleration vector (a) that has the same direction as the Velocity vector (v) incoming to the current object position (P). It represents the accelerating or decelerating force. In 3D the the calculation is the same: Every consecutive three points define a plane in which acceleration is computed.
Since three consecutive positions are needed to calculate Acceleration, its value for the first and the last track point is not available.
Figure 1593. Size of the acceleration vector
Figure 1594.
Heading is the the angle between the direction of the Velocity vector and the X axis. Zero degrees is in the direction of X axis (to the right) and increasing counterclockwise until 360.
Figure 1595.
Elevation is the angle between the direction of the Velocity vector and the XY plane. Positive Elevation is towards positive Z coordinates. The values range from -90 to 90.
Figure 1596.
Line Length is the length of a straight line from the track origin to the current point. The Line Speed is the Line Length divided by the time elapsed. It represents the speed of progression of a given object.
