If it's a well understood domain, up front design is nice. A simple drawing that fits on a sheet of paper. If it's new territory, up front design is worthless.

If it's a well understood domain, up front design is nice. A simple drawing that fits on a sheet of paper. If it's new territory, up front design is worthless. You've never attempted to create a facial recognition program before. Not too long ago, no one else had either so there wasn't a lot of useful content to study. Your best bet is to try making 1 small useful unit of work, iterate, try again. Fit the pieces you create to achieve a goal. A design is grown from the bottom up. Now you have a better understanding of the problem and may be able to do some design.