pd_image() makes a spatial image plot of the specified prism
data (single variable and time step.). It is meant for rapid visualization,
but more detailed plots will require other methods.
prism_image() is the deprecated version of
pd_image(pd, col = "heat") prism_image(prismfile, col = "heat")
the color pattern to use. The default is heat, the other valid option is "redblue".
gg object of the image.