The CAD drawing which is displayed on the screen has been changed and the correctional transformation, based on the work in the academic article on the previous page (page D11), has been applied to the internal architecture of the building. The trial passage has also been duplicated on the drawing and you can see the second set of trial passages at the northern (right) end of the pyramid's base.
If you zoom in on the lower chamber you can see that the vertical axis of the geometry now passes through the vertical axis of the wall carving, known as the 'niche', which is located on the east wall of the lower chamber. The manner of formation of the niche can be seen if you start the clock. The two vertical lines that you can see on the screen are vertical projection lines which start at the lower and upper turning points of the principal ellipse. The lower turning point is, by definition, fixed to the base center of the building and so the projection line coming from it is static and stays in the center of the niche. The upper turning point, as was shown on the earlier page (page C3) moves from side to side in harmony with the rotation of the Earth, and the vertical projection line also moves from side to side and carves out the upper portion of the niche.
This shows that the transformation that has been applied to the drawing of the internal architecture is correct and that the niche that is located on the central vertical axis of the building is designed from the turning point projections.