Cost is a big part of the story, but the story has many other parts. Inversion, while being the only logical path to the best answer, is a path littered with pitfalls. The first pitfall is that the data is rarely able to determine a complete solution reliably. Generally there are aspects of the image that are not learnable from the data. In this chapter we study the simplest, most transparant example of data insufficiency.
Data exists at irregularly spaced positions in a plane.
We set up a cartesian mesh and we discover that some of the bins contain no data points.