  I discuss the use of cross correlations between galaxies with distance
information and projected weak lensing dark matter maps to obtain a fully three
dimensional dark matter map and power spectrum. On large scales l<100 one
expects the galaxies to be biased, but not stochastic. I show that this allows
a simultaneous solution of the full 3-D evolving galaxy bias and the dark
matter power spectrum simultaneously. Within the photo-z information of the CFH
lensing legacy survey, this allows a threefold reduction of statistical error,
while a cross correlation with CLAR or other deep spectroscopic surveys allows
a tenfold improvement in dark matter power accuracy on linear scales. This
makes lensing surveys more sensitive to the cosmic equation of state and the
neutrino masses.
