WEMSurfaceDistance

MLModule

genre	WEMProcessing
author	MeVis Medical Solutions AG
package	MeVisLab/Standard
dll	MLWEMModules
definition	MLWEMModules.def
see also	WEMImageData, SoWEMRenderer
inherits from	WEMProcessor
keywords	measure, minimal

Purpose

The module WEMSurfaceDistance calculates the minimal distances of the nodes of one WEM to the nodes of another WEM.

These distances are stored in the nodes’ WEMPrimitiveValueList entries of the output WEM for a later LUT coloring or for further analysis.

Usage

Connect to WEM surfaces into the module’s inputs and connect the output to a renderer. Use the Min. Dist. and Max. Dist. values of the statistics section for LUT range adjustment.

Details

The nodes’ positions of the first input WEM are stored internally in a spherical space tree, which is build in O(n*log(n)), with n being the number of nodes. Then, this space tree is used to find the minimum distances to all node of the second input WEM. These obtained distances are stored in the according WEMPrimitiveValueList of the nodes of the output WEM.

Note that distances may be negative; if so, the second surface is under the first one, regarding the surface normal direction.

The module also outputs the positions of the nodes with the overall minimal distance.

The module produces three WEMPrimitiveValueLists: LUT, LUT Perpendicular and LUT Tangential.

• In LUT the closest distance of a node to another node of the other WEM is stored.
• In LUT Perpendicular the distance vector is projected onto the node’s normal; this gives a measure of how close the node of the other WEM is in that node’s normal direction.
• In LUT Tangential the distance is biased by a sideway shift; the distance value is larger if the corresponding closest node lies closer to the tangential plane of a node.

In the image above, all other nodes that lie on the sphere d have the same (unsigned) distance to the node N; this distance is stored in LUT. The node A lies in normal direction, thus the value in LUT Perpendicular is the same as the LUT value; the LUT Perpendicular value for node B is 0. For LUT Tangential, the distance to A is zero distance while the distance to node B is the actual distance.

Windows

Default Panel

Input Fields

inWEM

name: inWEM, type: WEM(MLBase)

A WEM surface for measuring the minimal distances to another WEM surface. This input WEM will be the copied to the output and the LUT values will be filled with the minimal distances.

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

inWEM2

name: inWEM2, type: WEM(MLBase)

A WEM surface for measuring the minimal distances to another WEM surface.

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

Output Fields

outWEM

name: outWEM, type: WEM(MLBase)

The output is the first of the input WEMs, of which the lutValue variable are modified to reflect the according node’s minimal distance to the surface of the second WEM.

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

Parameter Fields

Field Index

addEdgesToNearestNodes: Bool	isProcessing: Bool	numEntries: Integer
Apply: Trigger	Label: String	Overwrite label and description: Bool
Auto Apply: Bool	listenToFinishNotifications: Bool	progress: Float
Clear: Trigger	listenToRepaintNotifications: Bool	relativeError: Float
Compute signed distances: Bool	listenToSelectionChangedNotifications: Bool	shouldComputeNormals: Bool
Custom Value List: String	Max. Dist.: Float	Start Pos.: Vector3
Description: String	Max. Norm.: Float	triangulationMode: Enum
elapsedTime: Float	Min. Dist.: Float	Update Mode: Enum
End Pos.: Vector3	Min. Norm.: Float	Use default value list: Bool
id: Integer	Normalize distances: Bool	workDirectlyOnInputWEMs: Bool

Visible Fields

Auto Apply

name: autoApply, type: Bool, default: TRUE

If checked, the output WEM is computed anew on any parameter field change.

see also WEMGenerator.autoApply

Update Mode

name: updateMode, type: Enum, default: AutoUpdate, deprecated name: autoUpdate

Defines how this module should react on any input field change.

see also WEMGenerator.updateMode

Apply

name: apply, type: Trigger

If pressed, the output WEM is computed anew.

see also WEMGenerator.apply

Clear

name: clear, type: Trigger

If pressed, the output WEM is cleared (made empty).

see also WEMGenerator.clear

Overwrite label and description

name: overwriteLabelDescription, type: Bool, default: FALSE

If checked, label and description strings are set in the output WEM to Label and Description.

see also WEMGenerator.overwriteLabelDescription

Label

name: label, type: String

Sets a label string in the output WEM.

see also WEMGenerator.label

Description

name: description, type: String

Sets a description string in the output WEM.

see also WEMGenerator.description

Compute signed distances

name: shouldComputeSignedDistances, type: Bool, default: FALSE

If checked, the distances are signed, reflecting the spacial configuration of the surfaces (below / over). If unchecked, only the distances’ magnitudes are stored in the nodes’ WEMPrimitiveValueList.

Min. Dist.

name: minimumDistance, type: Float, persistent: no

Shows the minimum minimal distances of nodes of the two input WEMs.

Max. Dist.

name: maximumDistance, type: Float, persistent: no

Shows the maximum minimal distances of nodes of the two input WEMs.

Min. Norm.

name: minNormDist, type: Float, persistent: no

Shows the normalized minimum minimal distances of nodes of the two input WEMs.

Max. Norm.

name: maxNormDist, type: Float, persistent: no

Shows the normalized maximum minimal distances of nodes of the two input WEMs.

Normalize distances

name: shouldNormalizeDist, type: Bool, default: FALSE

If checked, all distances range in [0..1] or in [-1..1] (if signed distances are used), where 1 denotes the largest minimal distance. This option is useful if always the same (relative) LUT should be used.

Start Pos.

name: startPosition, type: Vector3, persistent: no

Shows the position of the node of the first WEM with the overall minimum distance.

End Pos.

name: endPosition, type: Vector3, persistent: no

Shows the position of the node of the second WEM with the overall minimum distance.

Use default value list

name: useLUTPrimitiveValueList, type: Bool, default: TRUE

If checked, the default WEMPrimitiveValueList named LUT is used to store the minmial distances.

Custom Value List

name: customPrimitiveValueList, type: String, default: Surface Distance

Sets a name for a WEMPrimitiveValueList the values should be written into. If the named list does not exist yet, it is generated.

Hidden Fields

isProcessing

name: isProcessing, type: Bool, persistent: no

see WEMGenerator.isProcessing

elapsedTime

name: elapsedTime, type: Float, persistent: no

see WEMGenerator.elapsedTime

id

name: id, type: Integer, default: 0

see WEMGenerator.id

shouldComputeNormals

name: shouldComputeNormals, type: Bool, default: TRUE

see WEMGenerator.shouldComputeNormals

workDirectlyOnInputWEMs

name: workDirectlyOnInputWEMs, type: Bool, default: FALSE

see WEMProcessor.workDirectlyOnInputWEMs

listenToFinishNotifications

name: listenToFinishNotifications, type: Bool, default: TRUE

see WEMProcessor.listenToFinishNotifications

listenToRepaintNotifications

name: listenToRepaintNotifications, type: Bool, default: TRUE

see WEMProcessor.listenToRepaintNotifications

listenToSelectionChangedNotifications

name: listenToSelectionChangedNotifications, type: Bool, default: TRUE

see WEMProcessor.listenToSelectionChangedNotifications

progress

name: progress, type: Float, persistent: no

see WEMProcessor.progress

triangulationMode

name: triangulationMode, type: Enum, default: Strip

see WEMProcessor.triangulationMode

relativeError

name: relativeError, type: Float, default: 0

numEntries

name: numEntries, type: Integer, default: 200

addEdgesToNearestNodes

name: addEdgesToNearestNodes, type: Bool, default: FALSE