Fig 1.
Photographing brain hemispheres.
Brain hemispheres were placed at the center of a non-refractile, transparent acrylic plate on a thin frame. A thin frame supported the acrylic plate, allowing photographs to be taken from various positions. Photographs were taken at horizontal intervals of 30 degrees on the horizontal plane (blue circle with shooting points). Photographs from above (yellow circle: -30 degrees and black circle: -60 degrees) and photographs from below (red circle: +30 degrees and green circle: +60 degrees) were taken similarly at horizontal intervals of 30 degrees. Camera directions are indicated by arrows (for the right half of the figure).
Fig 2.
3D determination of the target position relative to cameras using epipolar geometry.
a Conventional triangulation: The positions of two cameras C1(x1,y1,z1) and C2(x2,y2,z2) are known. Since the target X is projected on a X1, X2 on images P1, P2, the position X(x3,y3,z3) can be calculated as a point where a straight line connecting C1 and X1 overlaps with a straight line connecting C2 and X2. b Epipolar geometry: Because the positions of cameras were unknown in this study, the putative position of the target relative to the cameras was calculated as follows. The plane consisting of X and the positions of virtual cameras C1’ and C2’ is called an epipolar plane. The straight line connecting C1’ and C2’ is called a baseline (green line). The line where the epipolar plane intersects P1’, P2’ is called an epipolar line (red line), and the point where the baseline and the epipolar line intersect is called an epipole (E1, E2). c Positioning of X and cameras when the positions of the cameras are unknown: When there are multiple target points, the epipolar plane moves, but the baseline is fixed, so all epipolar lines go through the same epipole. This principle can be used to calculate the relative positions of the two cameras and the common targets in 3D space. C1,C2: camera positions. C1’,C2’: virtual camera positions. P1,P2: images taken by C1,C2. P1’, P2’: images taken by C1’,C2’. X: target point. X1,X2: X on P1,P2. E1,E2: epipole.
Fig 3.
Macroscopic photo of formalin-fixed human normal brain hemisphere with no neuropathological signs (right hemisphere). Scale bar = 1 cm.
Fig 4.
Macroscopic photo of formalin-fixed human PSP brain hemisphere (left hemisphere): Mild atrophy is present in the frontal lobe (arrows). Scale bar = 1 cm.
Fig 5.
Macroscopic photo of formalin-fixed human ALS brain hemisphere (left hemisphere): Subtle atrophy is seen in the superior temporal gyrus (arrows). Scale bar = 1 cm.