Description
Compare supplied marker-pair distance with a reference segment length.
Movement geometry depends on coordinate registration, time origins, force signs and reference axes. A moment arm must already represent perpendicular leverage, a stride percentage has an endpoint convention, and a toe-to-heel projection differs from full Euclidean separation. Scalar results do not establish a movement diagnosis or a safe activity.
Compare supplied marker-pair distance with a reference segment length.
When to use this tool
Use Motion Marker Rigid Segment Length Residual when you already have firstMarker, secondMarker, referenceLength and need to compare supplied marker-pair distance with a reference segment length.
How to use the tool and how it works
- Enter firstMarker, secondMarker, referenceLength. Follow any array-alignment requirements below. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read measuredLength, lengthResidual. Use the output convention below.
Require equal-length nonempty coordinate arrays and referenceLength>=0; calculate Euclidean distance with Math.hypot of differences and subtract referenceLength.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstMarker | Nonempty coordinate vector aligned in dimension, frame and units with secondMarker; not restricted to three dimensions. | Required. Array of finite number; maximum items 256. |
| secondMarker | Second Marker | Required. Array of finite number; maximum items 256. |
| referenceLength | Reference Length | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| measuredLength | Measured Length | Required. Finite number. |
| lengthResidual | Length Residual | Required. Finite number. |
{
"input": {
"firstMarker": [
0,
0,
0
],
"secondMarker": [
3,
4,
0
],
"referenceLength": 4
},
"output": {
"measuredLength": 5,
"lengthResidual": 1
}
}Limitations and assumptions
- Dimension and units are caller-defined, not limited to 3D. No marker tracking, rigid-body validity, calibration, anatomical segment or clinical result is verified.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated motion, force and timing records with a complete biomechanical model. Check coordinate frames, axis normalization and sampling limitations before interpreting local distances, moments or phase values as performance or clinical findings.
References
Similar or alternative tools
- Marker Segment Relative Coordinate
Subtract a supplied three-dimensional origin from a marker coordinate.
- Gait Toe Heel Distance Projection
Project supplied heel-to-toe displacement onto an almost-unit forward axis.