WEMSubdivide¶

MLModule¶

genre	`WEMProcessing`
author	`MeVis Medical Solutions AG`
package	`MeVisLab/Standard`
dll	`MLWEMModules`
definition	MLWEMModules.def
see also	`WEMReducePolygons`
inherits from	`WEMProcessor`
keywords	`split`, `surface`

Purpose¶

The module WEMSubdivide can be used to subdivide a WEM in order to produce more nodes, edges, and faces without modifying the overall geometry.

Details¶

Note: This module works on triangles only!

The WEMSubdivide module searches exhaustively in a WEM for edges with lengths that exceed an adjustable length threshold. Such an edge is split by inserting a node into the middle of the corresponding edge (and additionally, two edges and two faces are inserted into the WEM). Internally, a priority queue is used; because of this, the longest edges are split first. Additionally, after each run of splitting edges, the module attempts to optimize the triangles by applying an edge-swap operation. Furthermore, the faces’ normals are smoothed before checking for a potential swap.

Tips¶

The average edge length can be determined with the WEMInfo.

Windows¶

Default Panel¶

../../../Modules/ML/MLWEMModules/mhelp/Images/Screenshots/WEMSubdivide._default.png

Input Fields¶

inWEM¶

name: inWEM, type: WEM(MLBase)¶: Any valid WEM that contains only triangles.

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

Output Fields¶

outWEM¶

name: outWEM, type: WEM(MLBase)¶: The subdivided WEM.

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

Parameter Fields¶

Field Index¶

`Apply`: `Trigger`	`listenToFinishNotifications`: `Bool`	`PVL Name`: `String`
`Auto Apply`: `Bool`	`listenToRepaintNotifications`: `Bool`	`PVL Threshold`: `Double`
`Clear`: `Trigger`	`listenToSelectionChangedNotifications`: `Bool`	`shouldComputeNormals`: `Bool`
`Description`: `String`	`Local Subdivision`: `Bool`	`Subdivision Mode`: `Enum`
`elapsedTime`: `Float`	`Max Iterations`: `Integer`	`triangulationMode`: `Enum`
`id`: `Integer`	`Max. Edge Length`: `Float`	`Update Mode`: `Enum`
`isProcessing`: `Bool`	`Overwrite label and description`: `Bool`	`workDirectlyOnInputWEMs`: `Bool`
`Label`: `String`	`progress`: `Float`

Visible Fields¶

Auto Apply¶

name: autoApply, type: Bool, default: TRUE¶: If checked, all parameter changes take immediately effect.

Update Mode¶

name: updateMode, type: Enum, default: AutoUpdate, deprecated name: autoUpdate¶: Defines how this module should react on any input field change.

Apply¶

name: apply, type: Trigger¶: When pressed, the subdividing algorithm is applied to the WEM.

Clear¶

name: clear, type: Trigger¶: When pressed, the output WEM is cleared (made empty).

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.

Label¶

name: label, type: String¶: Sets a label string in the output WEM.

Description¶

name: description, type: String¶: Sets a description string in the output WEM.

Subdivision Mode¶

name: subdivisionMode, type: Enum, default: Adaptive Subdivision¶: Defines the subdivision mode.

Values:

Title	Name	Description
Split Each Edge Once	Split Each Edge Once	Each edge is split into two edges, independent of the edge length.
Adaptive Subdivision	Adaptive Subdivision	Each edge is recursively split in half until the resulting new edges are not longer than `Max. Edge Length`. Thus, each edge results in 2ⁿ edges, with n being determined adaptively for each edge.

Max. Edge Length¶

name: maxEdgeLength, type: Float, default: 1¶: Sets the maximum length an edge can have in a WEM. If any edge exceeds this length, it will be split by inserting a node in the middle of that edge.

Local Subdivision¶

name: localSubdivision, type: Bool, default: FALSE¶: If enabled, the PVL Name Primitive Value List is used to determine if an edge should be subdivided.

PVL Name¶

name: localSubdivisionPVL, type: String, default: LUT¶: Sets the name of the Primitive Value List (PVL) to use (only node and edge PVLs are supported).

PVL Threshold¶

name: localSubdivisionPVLThreshold, type: Double, default: 1¶: Sets the threshold for the Primitive Value List (PVL) value. If the PVL value is greater than or equal to the threshold, the edge can be subdivided.

Max Iterations¶

name: maxIterations, type: Integer, default: 1000000¶

Sets the maximum number of iterations. A value of -1 indicates that no limit is imposed.

By iteration, a splitting of an edge is meant. If the algorithm stops before all edges have been split according to the length criterion, the result is a valid WEM containing edges longer than the Max. Edge Length.