zaxis

In mathematics and computer graphics, the z-axis is the third axis in a three-dimensional Cartesian coordinate system. It consists of all points with coordinates (0, 0, z) and is perpendicular to the x–y plane. In a standard right-handed coordinate system, the positive direction of z is determined by the order of the x and y axes, with x cross y equaling z.

Conventions for the orientation of the z-axis vary by discipline. In many math and physics contexts, z is treated as the vertical or depth dimension relative to a reference plane. In computer graphics and CAD, z is often interpreted as depth from the viewer, and the sign convention for z can differ between APIs and pipelines. As a result, the same z-value can correspond to different spatial locations depending on the context.

The z-axis is central to 3D geometry and modeling. It is the axis along which vectors have their z-component and can serve as the axis of translation or rotation in various applications. In cylindrical coordinates, a point is described by (r, θ, z), where z denotes height. In robotics, the z-axis often represents vertical travel; in geoscience, it can denote elevation; in 3D printing, the printer head moves along z to build successive layers. Understanding the z-axis thus relies on the underlying coordinate system conventions used in a given field or software.