Set Logarithmic Axis for TH3 plot (glbox, glcol)

Is there a mechanism for setting the “4th axis” (w?) in a TH3 plot to a logarithmic value? SetLogz does not seem to work.

No … Sorry. The log option can be set only on X Y and Z dimensions … But in any case you will never see an Axis on the 4th dimension … what you ask for is to get the log on the bin contents. On way would be to make a new histogram this way.