Improved mirror ball projection for more accurate merging of multiple
  camera outputs and process monitoring
Wladislav Artsimovich Yoko Hirono
Using spherical mirrors in place of wide-angle cameras allows for
cost-effective monitoring of manufacturing processes in hazardous environment,
where a camera would normally not operate. This includes environments of high
heat, vacuum and strong electromagnetic fields. Moreover, it allows the
layering of multiple camera types (e.g., color image, near-infrared,
long-wavelength infrared, ultraviolet) into a single wide-angle output, whilst
accounting for the different camera placements and lenses used. Normally, the
different camera positions introduce a parallax shift between the images, but
with a spherical projection as produced by a spherical mirror, this parallax
shift is reduced, depending on mirror size and distance to the monitoring
target.
  This paper introduces a variation of the 'mirror ball projection', that
accounts for distortion produced by a perspective camera at the pole of the
projection. Finally, the efficacy of process monitoring via a mirror ball is
evaluated.