Registering images or vectors requires that their geometry be altered to fit another geometry taken as a reference. The process consists of two steps. First, a transformation model is built. Second, the images or vectors are resampled through this transformation model.

Throughout this chapter, the terms base and uncorrected are used with a very specific meaning:

• The base is the system of coordinates taken as a reference and onto which the uncorrected data is registered. The base can be vectors, digital images, hard copy, a series of known points, or some other geometric source.

• The uncorrected data is a digital document targeted to fit the base after it is transformed through a mathematical model.