  A new model for the luminosity distribution in the inner Milky Way is found,
using a non-parametric penalized maximum-likelihood algorithm to deproject a
dereddened COBE/DIRBE L-band map of the inner Galaxy. The model is also
constrained by the apparent magnitude (line-of-sight) distributions of clump
giant stars in certain bulge fields. An important new feature is the inclusion
of a spiral arm model in the disk. Spiral arms make the model appear broader on
the sky, thus our bar is more elongated than in previous eight-fold symmetric
models. They also lead to a smoother disk model interior to the Sun. The bar
length is approx. 3.5kpc and its axis ratios are 1:(0.3-0.4):0.3, independent
of whether the spiral arm model is 4-armed or 2-armed. The larger elongation in
the plane makes it possible to reproduce the observed clump giant distributions
as well. For the bar angle we estimate 15^o <= phi <= 30^o, with the best
models obtained for 20^o <= phi <= 25^o. We use our reference model to predict
a microlensing optical depth map towards the bulge, normalising its mass by the
observed terminal velocity curve. For clump giant sources at (l,b)=(3.9,-3.8)
we find tau_{-6}:=tau/10^{-6}=1.27, within 1.8*sigma of the new MACHO
measurement given by Popowski et al. The value for all sources at
(l,b)=(2.68,-3.35) is tau_{-6}=1.1, still >3*sigma away from the published
MACHO DIA value. The dispersion of these tau_{-6} values within our models is
10%. Because the distribution of sources is well-fit by the NIR model,
increasing the predicted optical depths by >20% will be difficult. Thus the
high value of the measured clump giant optical depth argues for a near-maximal
disk in the Milky Way. (abridged)
