General description
We consider a volume, as a 3D image based on known size voxels, which is determined by the spacing between sections and their resolution; these values depend on the configuration and model of the medical imaging device used. The voxel grid is structured so that three-dimensional reconstructions are created from 2D images.
Volume types
- Scalar: Voxels with their spatial location and intensity/color value of the same (e. g. image)
- Label map: Voxels with associated information (e. g. text)
In Slicer a set of volumes makes up a scene. A volume can be a 3D representation of an individual element or a set of elements, along with their annotations.
Annotations
Annotations are extra information regarding certain parts of the volume. There are three types of notes:
- ROI: Acronym for Region Of Interest. It defines a three-dimensional prism and is usually used to select portions of the volume (as a pre-step to segmentations, for example)
- Fiducial: a marker that defines a position in 3D space, a marker.
- Rule: to measure the distance (linear) between two points.
Nodes
Nodes are created each time information is imported into Slicer, and node types are based on the information they store.
A MRML scene is a set of nodes, and all of them can be queried from the Data module.
