Inspect3D's main purpose is to help users explore their data in a way that is both intuitive and meaningful. That being the case, it's helpful to understand the types of data that are stored in .c3d files, .cmz files, and that Inspect3D is able to handle.

Parameters are individual metadata items from a .c3d file. These define the data collection process (e.g., the number of analog channels or the sampling rate) and specify the location and type of data within the file. Parameters may be as simple as a single number or as complex as a list of names.

An example of many time-normalized traces plotted for the AnkleAngleX signal.

Signals are data items recorded over time by your motion-capture or data-acquisition system. Mathematically, signals are discretely sampled functions whose independent variable is time. Signals may be scalar-valued (e.g., a single voltage output by a strain gauge) or vector-valued (e.g., the x,y,z coordinates of a target marker).

A trace can be thought of as the actual data (such as the time series {1.1, 1.7, 1.3, 0.9, 1.2,…}) associated with a particular signal (e.g., LAnkleMoment_X) at a particular time (e.g., frames 341-1518 of a recording). Traces are generally taken from the time period defined by an event sequence, such as RON (Right Foot On) followed by ROFF (Right Foot Off), and then time-normalized to allow for comparison between traces.

Events indicate specific moments in a .c3d file with semantic meaning, such as Right Heel Strike for walking or Arm Cock Start for throwing. Visual3D can automatically create gait events if the .c3d file includes force platform assignments, otherwise it is necessary to reconstruct these events from the file's kinematic data.

An example of many maximum ground reaction force metrics plotted.

It is sometimes useful to compute quantities which in some way collapse the time dimension of traces (e.g., the mean value of a trace over a duration) or the spatial dimension of models (e.g., the center of mass of entire model). These quantities are called metrics and they do not vary as a function of time or any other variable. A number of pipeline commands exist to calculate common metrics from signals.