  Disk scale length and central surface brightness for a sample of about 29955
bright disk galaxies from the Sloan Digital Sky Survey have been analysed.
Cross correlation of the SDSS sample with the LEDA catalogue allowed us to
investigate the variation of the scale lengths for different types of
disk/spiral galaxies and present distributions and typical trends of scale
lengths all the SDSS bands with linear relations that indicate the relation
that connect scale lengths in one passband to another. We use the volume
corrected results in the r-band and revisit the relation between these
parameters and the galaxy morphology. The derived scale lengths presented here
are representative for a typical galaxy mass of 10^10.8 solarmasses, and the
RMS dispersion is larger for more massive galaxies. We analyse the
scale-length-central disk brightness plane and further investigate the Freeman
Law and confirm that it indeed defines an upper limit for disk central surface
brightness in bright disks (r<17.0), and that disks in late type spirals (T >
6) have fainter central surface brightness. Our results are based on a sample
of galaxies in the local universe (z< 0.3) that is two orders of magnitudes
larger than any sample previously studied, and deliver statistically
significant results that provide a comprehensive test bed for future
theoretical studies and numerical simulations of galaxy formation and
evolution.
