Fig 3. Distribution of elevation difference between successive corneal topographies before and after elimination of misalignment using ICP algorithm: Case 1.

The first row shows contour maps of elevation difference in the common region of two successive anterior corneal topographies before (left) and after (right) elimination of misalignment using ICP algorithm, while the second row shows corresponding contour maps for posterior topographies. The four contour maps share the same colour scale (upright in μm). In this particular case, before ICP correction of misalignment, the RMS of fit error is 13.53 μm for both anterior and posterior surfaces, considered simultaneously, reduced to 7.24 μm (46.49% reduction) following the ICP correction.