3rd Dimention Triangulation (Quadrulation)

Normal triangulation of a location is taken from 3 points of measurement determining a specific location from the distance measure from the 3 point on a 2D plain.

Quadrulation (Pyramidulation) of a location is to determine a 3D locations by adding an extra point higher up on the Z axis.

The forth point of measurement can be used just like triangulation between all points to find the central location on the X, Y and Z plain.

In normal triangulation three distances from three location can be mapped easily on pen and paper, because it is 2D plain. When you add a forth dimention in a higher axis on the Z plain, you are able to measure in a 3D area based on the distance of 4 locations.