We have not implemented the specific suggestions of section
4.2 for the recovery of Euclidean structure from a
projective reconstruction by observing known scene angles,
circles,...However we have developed a more brute force approach,
finding a projective transformation *H* in equation
(5.4) that maps the projective reconstruction to
one that satisfies a set of redundant Euclidean constraints. This
simultaneously minimizes the error in the projection equations and the
violation of the constraints. The equations are highly nonlinear and
a good initial guess for the structure is needed. In our experiments
this was obtained by assuming parallel projection, which is linear and
allows easy reconstruction using SVD decomposition ([26]).

Figures 5.3 and 5.4 show an example of this
process.