Folding-free global conformal mapping for genus-0 surfaces by harmonic energy minimization

Surface conformal maps between genus-0 surfaces play important roles in applied mathematics and engineering, with applications in medical image analysis and computer graphics. Previous work (Gu and Yau in Commun Inf Syst 2(2):121-146, 2002) introduces a variational approach, where global conformal parameterization of genus-0 surfaces was addressed through minimizingtheharmonic energy,with twoweaknesses: its gradientdescent iteration is slow, and its solutions contain undesired parameterization foldings when the underlying surface has long sharp features. In this paper, we propose an algorithm that significantly accelerates the harmonic energy minimization and a method that iteratively removes foldings by taking advantages of the weighted Laplace-Beltrami eigen-projection. Experimental results show that the proposed approaches compute genus-0 surface harmonic maps much faster than the existing algorithm in Guand Yau (Commun Inf Syst 2(2):121-146, 2002) and the new results contain no foldings.