A volume pixel or voxel is a point in three-dimensional space. A voxel defines a position with three coordinates in x, y, and z directions. A voxel is a fundamental unit for representing 3D images. They are mostly used in CAT scans, X-rays, and MRIs to create an accurate 3D model of the human body and other 3D objects. To work with 3D images, it is very important to understand voxels as these are what 3D images are made of. The following diagram is included to give you an understanding of what a voxel in a 3D image looks like:
A series of voxels in a 3D image. The shaded region is a single voxel.
The preceding image is a stacked representation of voxels. The gray-colored cuboid represents one voxel. Now you understand what a voxel is, let's load and visualize 3D images in the next section.