Purpose

The module MarkerStatistics performs simple statistical computations on a list of marker positions provided at its input.

The computed results include the Center of Gravity, Std Deviation and Variance, as well as some directional values dependent on a specified Direction vector. For the computation of these values, the input marker positions are ordered along an axis parallel to the Direction vector and order statistics is applied (minimum, maximum, median, quantiles).

Usage

Connect an ml.XMarkerList object to the input of this module.

If desired, specify a Direction vector and a Quantile value.

Details

All computations are performed on the 3D spatial components of the input markers. The t-, c, and u-components as well as the vector properties are completely ignored.

The computation of the directional order statistics (minimum, maximum, median, quantile) requires sorting the input markers along the specified direction. For large marker lists, this can be time consuming. The option Enable order statistics can be used to enable or disable the computation of these values.

Windows

Default Panel

../../../Modules/ML/MLGeometry1/mhelp/Images/Screenshots/MarkerStatistics._default.png

Input Fields

inMarkerList

name: inMarkerList, type: XMarkerList(MLBase)

Input marker list.

For accessing this object via scripting see the Scripting Reference: MLXMarkerListWrapper.

Parameter Fields

Field Index

Center of Gravity: Vector3 Projection Axis: Enum Variance (dirVariance): Double
Direction: Vector3 Quantile: Double  
Enable order statistics: Bool Std Deviation (stdDev): Double  
Maximum: Vector3 Std Deviation (dirStdDev): Double  
Median: Vector3 Up To Date: Bool  
Minimum: Vector3 Update: Trigger  
Num Markers: Integer Update Mode: Enum  
Position: Vector3 Variance (variance): Double  

Visible Fields

Num Markers

name: numMarkers, type: Integer, persistent: no

Shows the amount of markers in the input marker list.

Center of Gravity

name: centerOfGravity, type: Vector3, persistent: no

Shows the average position over all markers.

Variance (variance)

name: variance, type: Double, persistent: no

Shows the variance over all markers.

Std Deviation (stdDev)

name: stdDev, type: Double, persistent: no

Shows the standard deviation over all markers.

Direction

name: direction, type: Vector3, default: 0 0 0

Shows the direction along which the statistics are evaluated.

The vector is automatically normalized, i.e. the length of this vector is irrelevant. Specifying a value of (0 0 0) disables the computation of directional information.

Variance (dirVariance)

name: dirVariance, type: Double, persistent: no

Shows the variance of all marker positions along the specified direction.

Std Deviation (dirStdDev)

name: dirStdDev, type: Double, persistent: no

Shows the standard deviation of all marker positions along the specified direction.

Enable order statistics

name: enableOrderStats, type: Bool, default: TRUE

If checked, the computation of the order statistics (results) is based on sorting the input markers along the specified direction.

Projection Axis

name: projectionAxis, type: Enum, default: Off

Defines the axis on which the position values are projected.

Values:

Title Name Description
Off Off No projection is performed.
Mean Mean Positions are projected on the axis running through the center of gravity.
Median Median Positions are projected on the axis running through the median position.

Minimum

name: dirMinimum, type: Vector3, persistent: no

Shows the minimum marker position along the specified direction.

Maximum

name: dirMaximum, type: Vector3, persistent: no

Shows the maximum marker position along the specified direction.

Median

name: dirMedian, type: Vector3, persistent: no

Shows the median marker position along the specified direction.

Quantile

name: dirQuantile, type: Double, default: 0, minimum: 0, maximum: 1

Sets the relative quantile for which the position is computed.

This value ranges from 0 (corresponding to the minimum position) to 1 (maximum position). If the number of markers is odd, the value 0.5 corresponds to the median position.

Position

name: dirQuantilePos, type: Vector3, persistent: no

Shows the position corresponding to the specified relative quantile value.

Update Mode

name: updateMode, type: Enum, default: AutoUpdate

Defines the update mode of this module.

Values:

Title Name Description
Off Off The module does nothing on any change.
Auto Clear AutoClear The module clears all statistics on any change of the input marker list.
Auto Update AutoUpdate The module computes all statistics anew on any change of the input marker list.

Update

name: update, type: Trigger

If pressed, the module computes all statistics anew.

Up To Date

name: upToDate, type: Bool, persistent: no

Shows if the statistics shown are up-to-date.