An improved apparatus and method for creating high quality virtual reality
panoramas is disclosed that yields dramatic improvements during the
authoring and projecting cycles, with speeds up to several orders of
magnitude faster than prior systems. In a preferred embodiment, a series
of rectilinear images taken from a plurality of rows are pairwise
registered with one another, and locally optimized using a pairwise
objective function (local error function) that minimizes certain
parameters in a projective transformation, using an improved iterative
procedure. The local error function values for the pairwise registrations
are then saved and used to construct a quadratic surface to approximate a
global optimization function (global error function). The chain rule is
used to avoid the direct evaluation of the global objective function,
saving computation. In one embodiment concerning the blending aspect of
the present invention, an improved procedure is described that relies on
Laplacian and Gaussian pyramids, using a blend mask whose boundaries are
determined by the grassfire transform. An improved iterative procedure is
disclosed for the blending that also determines at what level of the
pyramid to perform blending, and results in low frequency image components
being blended over a wider region and high frequency components being
blended over a narrower region. Human interaction and input is also
provided to allow manual projective registration, initial calibration and
feedback in the selection of photos and convergence of the system.