SensoTech is a leading supplier of process analyzers for the in-line measurement of concentration and density in liquid processes. Typical further applications are the phase interface detection or the monitoring of complete chemical reactions like polymerisation or crystallization.
To make a density map from a 2D set of data, the first step is to compute values for the third dimension. (Gnuplot has no facilities for computing these values automatically.) The simplest way is to make a 2D histogram; the plot is divided in small 2D regions, and the z-values are proportional to the number of points inside these regions. The following Python script will make an histogram from a time series of two dihedral angles.
R. Bommakanti, G. Bokoch, J. Tolley, R. Schreiber, D. Siemsen, K. Klotz, and A. Jesaitis. J Biol Chem, 267 (11):
7576-81(April 1992)Bommakanti, R K Bokoch, G M Tolley, J O Schreiber, R E Siemsen, D
W Klotz, K N Jesaitis, A J R01-AI22735/AI/NIAID NIH HHS/United States
R01-GM39434/GM/NIGMS NIH HHS/United States Research Support, Non-U.S.
Gov't Research Support, U.S. Gov't, P.H.S. United states The Journal
of biological chemistry J Biol Chem. 1992 Apr 15;267(11):7576-81..