  Recent work has shown that the correlation between SDSS colors and optical
albedo can be used to estimate asteroid sizes from optical data alone. We
revisit a correlation between SDSS colors and optical albedo for asteroids,
with the albedo derived using WISE-based size estimates. Moeyens, Myhrvold \&
Ivezi\'{c} (2020) showed that this correlation can be used to estimate asteroid
sizes with optical data alone, with a precision of about 17\% relative to
WISE-based size estimates. We present here several more sophisticated
data-driven models for the variation of optical albedo with colors and estimate
the contribution of SDSS photometric errors to the albedo and size estimate
uncertainties. We use the results of our analysis to predict that LSST data
will enable asteroid size precision of about 15\% relative to WISE-based size
estimates. Compared to the accuracy of WISE-based size estimates of 15-20\%,
the implied accuracy of optical size estimates, in the range 21-25\%, is thus
only a factor of 1.3 to 1.4 worse. This size estimation accuracy is
significantly better than commonly assumed for optical data and is due to
accurate and homogeneous multi-band photometry delivered by modern digital sky
surveys.
