There are functions available in MATLAB which can perform 1-D, 2-D, or 3-D data interpolation. The function names are 'interp1', 'interp2' and 'interp3'. Depending on how many variables you have, you can try using the corresponding function to interpolate your data before using 'pcolor' to create the pseudocolor plot.
It may be a good idea to check out the section titled 'Interpolation' in the doc page below:
