It's my educated guess and pure speculation from me, They are not done at ground level, it's frankly impossible to get that level of detail and accuracy by hand/eye and what ground based machine could achieve that accuracy and consistency? so logic leads me to satellites and X/Y plotters driving a beam of some type. input by a CGI program.

It's my educated guess and pure speculation from me, They are not done at ground level, it's frankly impossible to get that level of detail and accuracy by hand/eye and what ground based machine could achieve that accuracy and consistency? so logic leads me to satellites and X/Y plotters driving a beam of some type. driven by a CGI program.