Abstract
While several mosaicking algorithms have been developed to compose endoscopic images of the internal urinary
bladder wall into panoramic images, the quantitative evaluation of these output images in terms of
geometrical distortions have often not been discussed. However, the visualization of the distortion level is
highly desired for an objective image-based medical diagnosis. Thus, we present in this paper a method to
create quality maps from the characteristics of transformation parameters, which were applied to the endoscopic
images during the registration process of the mosaicking algorithm. For a global first view impression,
the quality maps are laid over the panoramic image and highlight image regions in pseudo-colors according
to their local distortions. This illustration supports then surgeons to identify geometrically distorted structures
easily in the panoramic image, which allow more objective medical interpretations of tumor tissue in
shape and size. Aside from introducing quality maps in 2-D, we also discuss a visualization method to map
panoramic images onto a 3-D spherical bladder model. Reference points are manually selected by the surgeon
in the panoramic image and the 3-D model. Then the panoramic image is mapped by the Hammer-Aitoff
equal-area projection onto the 3-D surface using texture mapping. Finally the textured bladder model can
be freely moved in a virtual environment for inspection. Using a two-hemisphere bladder representation,
references between panoramic image regions and their corresponding space coordinates within the bladder
model are reconstructed. This additional spatial 3-D information thus assists the surgeon in navigation,
documentation, as well as surgical planning.
