The above title will probably not be unfamiliar to the readers of The Mathematica Book 5, the former being the topic of the Section 7, Chapter 9, Part 1 of the latter, where three functions are provided:
It was shown there that, e.g., the output of
Plot3D can be transformed into one like the output of
ContourGraphics. But the problem is that I only found the above three functions deprecated when I tried to figure out how to use them. And
GraphicsComplex is claimed to be the new version function to do the job, the documentation of which, however, seems not covering the topic.
So, how to realize the conversions among the three kinds of graphics (outputs from
Plot3D) in newer verions of Mathematica, say after V. 11?