PathToKeyFrame

MLModule
genre Resample
author MeVis Medical Solutions AG
package MeVisLab/Standard
dll MLResample1
definition MLResample1.def
see also MPRPath
keywords Marker, KeyFrameList, Curved, MPR

Purpose

The module PathToKeyFrame accepts a list of marker positions (an object of type ml.XMarkerList or ml.Vec3fList) and generates a keyframe list, i.e., a sequence of positions and viewing orientations.

The generated keyframe list is typically used by an MPRPath module to create curved MPR views.

Usage

Connect a marker list (e.g., from a SoView2DMarkerEditor module) to the input node and connect the output node to an MPRPath module.

Details

There are up to four different paths involved depending on the active processing steps:

  • The original input path (e.g., an XMarkerList) connected to inputKeys.
  • The smoothed path, which is different from the input path if Smoothing is non-zero. A simple convolution is applied in each step, so the result also depends on the sampling of the input path. While the number of points is the same as in the input path, the shape is smoothed and the overall length may be reduced (depending on the original curvature).
  • If Projection Mode is PathProjection, the output is a projected path, which has the same number of points as the original/smoothed path but lies within a plane.
  • The resampled path is computed from by linear resampling of the path every Resolution millimeter. The resampled path has (approximately) the same shape and overall length as the smoothed/projected path, but a different number of sampling points.

The Path Shift introduces an additional offset vector between the input path and the result.

The fields Input Path Length, Pos. Relative, and Pos. World refer to the smoothed path, not to the input path.

Indices are only changed by the resampling, not by shifting, smoothing, or projection, and the indices before/after resampling can be converted into each other via Original Index and Resampled Index.

Windows

Default Panel

../../../Modules/ML/MLResample1/mhelp/Images/Screenshots/PathToKeyFrame._default.png

Input Fields

inputKeys

name: inputKeys, type: PointList/XMarkerList/Vec3fList(MLBase)

An object of type ml.XMarkerList or ml.Vec3fList is expected at the input node. For compatibility to older modules, ml.PointList objects are also supported.

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

Output Fields

outputKeys

name: outputKeys, type: KeyFrameList(MLBase)

The output holds a ml.KeyFrameList object.

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

outputResampledPath

name: outputResampledPath, type: XMarkerList(MLBase)

Resampled, but never projected path as XMarkerList.

This is only different from the KeyFrameList points if path projection is used (Projection Mode is PathProjection), where outputResampledPath is particularly useful for displaying the original centerline on top of the stretched CPR.

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

Parameter Fields

Visible Fields

Smoothing

name: numSmoothes, type: Integer, default: 8, minimum: 0, maximum: 20

Sets the number of smoothing steps.

The smoothing is performed by iterative convolution with a 1-2-1 filter. A value of zero disables smoothing.

Resolution

name: outputResolution, type: Double, default: 0

Sets the sampling resolution of the generated keyframe list.

It is specified as the distance in millimeters between two consecutive positions. If the resolution is set to zero, resampling is disabled.

Auto path direction

name: autoPathDir, type: Bool, default: FALSE

If checked, a path primarily oriented toward the negative z-direction is automatically reversed.

Allow Reverse View

name: allowReverseView, type: Bool, default: FALSE

If checked, the selection of the viewing orientation tries to generate views as close as possible to one of the standard radiological viewing directions (axial, coronal, sagittal).

If Allow Reverse View is enabled, this may result in ‘backward’ viewing directions, i.e., views towards the reverse path direction.

Num Output Keys

name: numOutputKeys, type: Integer, persistent: no

Shows the number of keyframes in the output keyframe path.

Path Length

name: pathLength, type: Double, persistent: no

Shows the total length of the output keyframe path.

Path Shift

name: pathShift, type: Vector3, default: 0 0 0

Sets a translation vector to shift the output keyframe path.

Projection Mode

name: projectionMode, type: Enum, default: Off, deprecated name: projectUpVectors

Defines the projection mode.

Values:

Title Name Deprecated Name Description
Off Off FALSE Projection of keyframe positions and orientation is disabled.
Path Projection PathProjection  

The path is projected on a plane centered about the average path axis.

The projection takes place before the resampling step in order to achieve the desired path resolution.

The parameters Angle and Max. Distance influence the outcome if this option is chosen.
View Projection ViewProjection TRUE

The keyframe up-vectors are projected onto a common viewing direction, which can be specified either as a direction vector or by two angles.

The parameters Direction, Latitude, and Longitude influence the outcome if this option is chosen.

Direction

name: viewDir, type: Vector3, default: 0 1 0

Sets the viewing direction as a vector.

Latitude

name: viewLatitude, type: Double, default: 0, minimum: -90, maximum: 90

Sets the viewing direction as a latitude angle.

Longitude

name: viewLongitude, type: Double, default: 0, minimum: -180, maximum: 180

Sets the viewing direction as a longitude angle.

Override path direction

name: useOverridePathDir, type: Bool, default: FALSE

Sets whether to use Path Direction for the path projection.

Path Direction

name: overridePathDir, type: Vector3, default: 0 0 0

Sets a path direction to use instead of the actual mean path direction for the path projection.

This is only used if Override path direction is set and Projection Mode is PathProjection.

If the direction value is (exactly) 0 0 0, the mean path direction is used instead.

Override path center

name: useOverridePathCenter, type: Bool, default: FALSE

Path Center

name: overridePathCenter, type: Vector3, default: 0 0 0

Angle

name: projectPathAngle, type: Double, default: 0, minimum: 0, maximum: 360

Sets the rotation angle of the projection plane about the average path axis.

Max. Distance

name: maxProjectionDistance, type: Double, persistent: no

Sets the maximum distance of a path point to the average path axis.

This value is useful to specify the field of view necessary for a single-curved MPR.

Pos. World (pathPositionWorld)

name: pathPositionWorld, type: Vector3, persistent: no

Shows a position of the output path depending on the relative parameter Pos. Relative.

Pos. Relative (pathPositionRelative)

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

Sets the relative ‘index’ into the output path to display the Pos. World.

Pos. World (inputPathPositionWorld)

name: inputPathPositionWorld, type: Vector3, persistent: no

Shows a position of the input path depending on the relative parameter Pos. Relative.

Pos. Relative (inputPathPositionRelative)

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

Sets the relative ‘index’ into the input path to display the Pos. World.

Input Path Length

name: inputPathLength, type: Double, persistent: no

Shows the length of the input path.

Original Index

name: originalPathIndex, type: Double, default: 0, minimum: 0

Sets an index on the original path that corresponds to Resampled Index after resampling.

Resampled Index

name: resampledPathIndex, type: Double, default: -1, minimum: 0, maximum: -1

Sets an index on the resampled path that corresponds to Original Index before resampling.