The Korn-Lichtenstein partial differential equations subject to an int
egrability condition of Laplace-Beltrami type which govern conformal m
apping are reviewed. They are completed by an extensive review of defo
rmation measures (Cauchy-Green deformation tenser, Euler-Lagrange defo
rmation tenser, simultaneous diagonalization of a pair of symmetric ma
trices) extending the Tissot deformation portrait. W.r.t. one system o
f isometric parameters which cover a surface (oriented two-dimensional
Riemann manifold) the d'Alembert-Euler equations (Cauchy-Riemann equa
tions) subject to an integrability condition of Laplace-Beltrami type
are solved in real analysis by various systems of functions (fundament
al solution: ad-polynomial, separation of variables) plus a properly c
hosen boundary value problem, namely the equidistant mapping of one pa
rameter line. Finally the optimal universal transverse Mercator projec
tion is outlined by solving a boundary value problem of the d'Alembert
-Euler equations (Cauchy-Riemann equations) of a biaxial ellipsoid (el
lipsoid of revolution) where a dilatation factor of a central meridian
is to be determined. It is proven that for a non-symmetric and a symm
etric UTM strip the total areal distortion approaches zero once the to
tal departure from an isometry is minimized. According to the ''Geodet
ic Reference System 1980' for a strip [I-(E), + I-E] x [B-s, B-N] = [-
3.5, + 3.5 degrees] x [80 degrees S, 84 degrees N]- the standard UTM s
trip - an optimal dilatation factor is rho = 0.999, 578, while for a s
trip [-2 degrees, + 2 degrees] x [80 degrees S, 84 degrees N] - the st
andard Gauss-Kruger strip - an optimal dilatation factor is rho = 0.99
9, 864.