  I derived a geometrical model of the penumbral magnetic field topology from
an uncombed inversion setup that aimed at reproducing the NCP of simultaneous
spectra in near-IR (1.56 mu) and VIS (630 nm) spectral lines. I inverted the
spectra of five photospheric lines with a model that mimicked vertically
interlaced magnetic fields with two components, labeled background field and
flow channels. The flow channels were modeled as a perturbation of the
background field with a Gaussian shape using the SIRGAUS code. The location and
extension of the Gaussian perturbation in the optical depth scale was then
converted to a geometrical height scale. I investigated the relative amount of
magnetic flux in the flow channels and the background field atmosphere. The
uncombed model is able to reproduce the NCP well on the limb side of the spot
and worse on the center side; the VIS lines are better reproduced than the
near-IR lines. The Evershed flow happens along nearly horizontal field lines
close to the solar surface. The magnetic flux that is related to the flow
channels makes up about 20-50% of the total magnetic flux in the penumbra. The
gradients obtainable by a Gaussian perturbation are too small for a perfect
reproduction of the NCP in the IR lines with their small formation height
range. Two peculiarities of the observed NCP, a sign change of the NCP of the
VIS lines on the center side and a ring structure around the umbra in the Ti
line at 630.37nm and the FeI line at 1565.2nm deserve closer attention. The
large fraction of magnetic flux related to the flow channel component could
allow to replenish the penumbral radiative losses in the flux tube picture.
