Optimization for reconstruction variance
Optimization for reconstruction variance

Achieved by replacing SVD-based pseudo-inverse with
an eigen solver pseudo inverse.

New function works in the same way: it decomposes
matrix to V*D*V^-1, then inverts diagonal of D
and composes matrix back.

The same way is used to deal with gauges - last
7 eigen values are getting zeroed.

In own tests gives approx 2x boost, without
visible affect on selected keyframe quality.

Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv