The art-creation tools have changed a lot! The above portrait is done in Adobe Illustrator with "vector tracing" technique. In the old days, to create an artwork like this, you need different brushes, canvas, inks, colour swatches and years of training on drawing and painting.
I don't have any painting/drawing training but still like to create something impressive. Digital art tools come in handy. digital pen/drawing pad (from wacom), Adobe Illustrator serve this purpose very well. To be honest, I have to spend lots of time (weeks) to study the original photo's lines, lights, shapes and also did a lot of experiments on colours and shadings. It's not easy, but it's doable to an untrained-self-claimed "artist".
some staging works posted here as well.
Those mesh lines are to form different colour shapes and they are called "vector lines". It means that their curves and lengths are controlled by a bunch of handle points, instead of just a point A to point B definition. To draw those lines initially, I used wacom digital pen and pad, then I can adjust the lines via handles. This way I don't have to be "perfect" when I first drew those lines, because I can always adjust them to the proper angle and length later. But to warn you, these "adjustments" took lots of time, depending on creator's experience. If you are a trained and experienced illustrator yourself, maybe you don't need to adjust those lines at all.
Colouring is also very time consuming. In the old days, the painters had to touch the certain spots over and over again, wiped off the top paintings, repainted the same spot again and again, until they were satisfied. But with Adobe illustrator (or any other modern tool), you can just use image "layers" to avoid "wipe-off-again-and-again" situation. For this portrait, I have maybe 100 layers: eyeball layer, upper eyelash layer, nose highlight layer... you name it. and I can control and try different colours very precisely without damaging other parts of the painting. Fantastic!
Overall, I call this portrait a machine helped, but still a hand-made visual art and very glad to see the final result.