Isn't regular point perspective that all axis-aligned lines meet at the one of the three points, whereas here all lines whatsoever eventually converge there?
This reminds me of the mathematical trick to make a "hollow earth" work, with us living on the inside: All rays of light are bent. You can never see the curvature of the earth (or it seems that we are living on the outside). The stars that seem to be at ~infinity are at the center of the sphere, and the sun is a ball of fire orbiting around the center, and so on.
Almost: all equal ratio lines (x=z+c, x=y+c, y=z+c where c is some constant) head off in a straight line towards their respective horizons, but all other non-axis-aligned lines converge at the vanishing points.
This reminds me of the mathematical trick to make a "hollow earth" work, with us living on the inside: All rays of light are bent. You can never see the curvature of the earth (or it seems that we are living on the outside). The stars that seem to be at ~infinity are at the center of the sphere, and the sun is a ball of fire orbiting around the center, and so on.