  We present a detailed surface density analysis of a large sample of simulated
collisionless mergers of disc galaxies with bulges (mass ratios 1:1, 2:1, 3:1,
4:1, and 6:1) and without bulges (mass ratios 1:1 and 3:1). They were
classified, according to their bulge--to--total ($B/T$) ratio, either as a
one-component system or as a two-component systems. In general projection
effects change the classification of a remnant. Only merger remnants of discs
with bulges show properties similar to observed early--type galaxies. Their B/T
ratios are in the range $0.2<B/T<1$. Surprisingly, the initial mass ratio has a
weak influence on the distributions of $B/T$, effective radius and S\'ersic
index $n$. For all one-component projections ($\approx 60%$ of all projections)
the S\'ersic index distribution peaks at $3<n<4$. However, the mass ratio is
tightly linked to the properties of the outer exponential components which
resemble pressure supported, spheroidal halos for 1:1 and 2:1 remnants and
elongated heated discs for 6:1 remnants. We found distinct correlations between
the fitting parameters which are very similar to observed relations (e.g.
larger bulges have lower effective surface densities). No indications for a
correlation between the surface density profiles and other global parameters
are found. The remnants have properties similar to giant elliptical galaxies in
the intermediate mass regime. A binary disc merger origin for all early-type
galaxies, especially the most massive ones, is unlikely. Observed nearby merger
remnants have properties similar to the simulated remnants. They can have
formed from binary disc mergers and might evolve into early--type galaxies
within a few Gyrs (abbreviated).
