In order for a MakerBot to be able to replicate in three dimensions, it needs
to be able to move in three dimensions. It uses a Cartesian coordinate sys-
tem to define the points in space where it needs to lay down material. The
Cartesian coordinate system is made up of three perpendicular numbered
lines and can be used to describe the positioning of a point in either a one
dimensional space (think of a line), a two dimensional space (now think of a
plane) or three dimensional space (now we're talking about a cube).
If we were laying an object out using the coordinate plane in two dimensions
( Figure 5-5 ), we would be using a grid made of two numbered perpendicular
lines. The area where the lines intersect is called “the origin” and is numbered
“0”. When laying out two dimensional objects on a grid, we call the horizontal
axis “X” and the vertical axis “Y”. We can then specify points on that grid by
using distinct pairs of numbers.
Figure 5-5. 2D coordinate system
When we extend our coordinate system into a third dimension (see
Figure 5-6 ), we add a third axis or “Z”. The addition of depth now means that
when we specify a point on the coordinate system, we need to use an ordered
triplet ( x,y,z ).