When loading any object (volume, mesh, ROI graph...), the real world is sampled. That is to say, the view is sampled according to the image's matrice and the voxels' resolution. So coordinates can be expressed in mm (real world) and in voxels (after sampling).
When you click on an object in a window, the position of the cursor appears in the console. This position is given in mm and in voxel if the object is a volume. After the position, you find the value of the voxel.
If the window contains several objects, the coordinates of each objects are displayed.
There are several coordinates systems (referentials) managed by Anatomist more or less automatically. That is to say some transformations can be loaded automatically either via BrainVISA, or by Anatomist. For example, if a volume is identified as a normalized volume (SPM), then the transformation toward SPM referential is loaded.
Object's referential : this is the real world sampled like explained before.
Talairach-AC/PC-Anatomist referential : In BrainVISA anatomical pipeline, an affine transformation is computed : it is based on AC and PC points indicated by the user on the anatomy.
Talairach-MNI template-SPM referential : Transformation applicated if the volume is normalized.
Note
Anatomist always loads a transformation from Talairach-AC/PC-Anatomist referential to Talairach-MNI template-SPM referential.The linked cursor position is defined from the origin of the object. You can move the cursor to an exact position by fixing x, y, and z via the window menu : Scene => Manually specify linked cursor position. . You can also use the shortcut Ctrl + P. You specify the coordinates in mm like this : x y z.