The use of perspective and tonal scales, to create the illusion of a 3 Dimensional object on a 2 Dimensional plane. 3D Ship Painting is working with certain visual angles, and moving up and down the tonal scale (Light to dark) of a select colour to trick the human mind into thinking that what you've drawn or painted is actually a physical, tangible object.
3D painting can be very breathtaking, realistic and at the same time captivating if you get the angle correct of vision. Creating such kind of 3D image is really challenging as you are creating a realistic 3 dimensional view out of a 2 dimensional painting