BundleAdjustment::rodrigues_to_matrix bug

[stanleylijilin]

In function : rodrigues_to_matrix，
the ct 's formula should be : double ct = (a == 0.0) ? 0.5f : (1.0f - std::cos(a)) / (a * a);

[simonfuhrmann]

https://github.com/simonfuhrmann/mve/blob/master/libs/sfm/bundle_adjustment.cc#L292

[flanggut]

You are correct! Thanks for spotting this. I pushed a fix.

[simonfuhrmann]

Did you confirm this doesn't cause a regression in the BA code? :)

[flanggut]

I did run two scenes to confirm it, yes :)