  Based on a new estimation of their thickness, the global properties of
relativistic slim accretion disks are investigated in this work. The resulting
emergent spectra are calculated using the relativistic ray-tracing method, in
which we neglect the self-irradiation of the accretion disk. The angular
dependence of the disk luminosity, the effects of the heat advection and the
disk thickness on the estimation of the black hole spin are discussed. Compare
to the previous works, our improvements are that we use the self-consistent
disk equations and we consider the disk self-shadowing effect. We find that at
the moderate accretion rate, the radiation trapped in the outer region of the
accretion disks will escape in the inner region of the accretion disk and
contribute to the emergent spectra. At the high accretion rate, for the large
inclination and large black hole spin, both the disk thickness and the heat
advection have significant influence on the emergent spectra. Consequently,
these effects will influence the measurement of the black hole spin based on
the spectra fitting and influence the angular dependence of the luminosity. For
the disks around Kerr black holes with $a=0.98$, if the disk inclination is
greater than $60^\circ$, and their luminosity is beyond 0.2 Eddington
luminosity, the spectral model which is based on the relativistic standard
accretion disk is no longer applicable for the spectra fitting. We also confirm
that the effect of the self-shadowing is significantly enhanced by the
light-bending, which implies that the non-relativistic treatment of the
self-shadowing is inaccurate. According to our results, the observed luminosity
dependence of the measured spin suggests that the disk self-shadowing
significantly shapes the spectra of GRS 1915+105, which might lead to the
underestimation of the black hole spin for the high luminosity states.
