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This specialized control allows to manually cut a sulci graph node into several parts. It can be done by selecting a single point (by clicking on a sulcus node at the desired position), or by selected several points which will be linked to form a cut line: Ctrl + left click sets points (the order is important), then the S key proposes a split line joining the selected points. When a split line (purple voxels line) is proposed, the user can validate and actually split by hitting (or re-hitting) the S key. Actions can be aborted before the split is actually done, by hitting the ESC key.
A more automatic mode allows to automatically subdivize large nodes: clicking on a node with Ctrl + right click will subdivize a single node.
Shift + right click on any node of a graph will apply the automatic subdivizion of all large nodes of a graph.
Note that after splitting, nodes are not automatically remeshed, graph relations have been altered, and all morphometric measurements on altered nodes are out of date. To be usable for sulci recognition and morphometry, the graph should go through an update process, which is available in BrainVISA.