FIGURE 6.

Determination of the anatomical axes. (A) The location of the brain B and eyes E _1,2, as indicated by the red and blue crosses, respectively, is combined with (B) geometric properties of the brain mask to derive the orientation of the brain in space. (C) The correct orientation of the inferior–superior axis IS and left–right axis LR is inferred by fitting an ellipsoid to the brain mask. This allows the construction of the plane H that contains the major ellipsoid axis a and is parallel to LR. The ellipsoid section lying within the half space which includes the eyes represents the inferior portion of the brain