• Rigid-body, or Euclidean transformations
  
  
• Preserve the shape of the objects that they act on
  
  
• Includes rotations and trnaslations (just as in two dimensions)

First we begin with a representation for 3-D points. We will consider points as column vectors. Thus, a typical point with coordinates (x, y, z) is represented as:



This is not the only possible representation. You may encounter textbooks that consider points as row vectors. What is most important is that you use a consistent representation.