A little history about the design process.
How we design today has very much changed from 40 years ago when we first started. In those days a survey was carried out with tapes, pencil and a survey book. These measurements were transposed onto graph paper, on a large drawing table then, 'inked' in with a classic 'rotring' pen. Of course the handy electric eraser was nearby to correct any errors. Once a layout had been produced a new sheet was laid over so that a design could be sketched out, then finally a finished drawing would be produced, and either a dyeline made or if small enough a photocopy, which was then hand coloured to create a presentation drawing.
This isometric drawing of a vegetable garden is a typical hand drawn example.
Today we have any number of CAD programs, with designers using combinations of hand finishing, photo-realistic renditions, 3D imaging and videos. All have a place, however apart from basic landscaping the final design is still very much the preserve of the creative designer, all that's changed is the method to present his creations, the time it takes to reach this point and most importantly the material quantities required, this makes pricing much much easier.
Here we have a computer draw, hand finished example.