Four equations, four
unknowns … but there are many possible answers because the equations are
not all independent
?
?
?
?
5
5
5
5
8
8
2
2
7
7
3
3
… etc but if vertical
ratio is known
to be 4:1
Problems
- incomplete data coverage
10
10
10
10
8
8
2
2
… then the solution is unique
If each of the measurements (integrated quantities)
are equal to 10, find the density in each pixel …
See for example Fremouw et al, 1992