Painting creatively is one thing. Recreating creative work is often even more difficult.
Dr. Bob and his 'Light Brigade" of artists were presented with the huge problem of accurately recreating the now lost images of the original bus from a few photos and drawings. When more high tech ideas didn't stand up to the challenges of the curved and cornered surfaces of the bus they opted for an ancient idea - the Grid Method.
Since ancient Egyptian times, artists have been using The Grid Method as a drawing tool to improve accuracy. The Egyptians used this method by ‘snapping’ a string soaked in red dye against their drawing surface to create their grid lines.
The Renaissance artists used The Grid Method a bit differently in their works. Using a wooden frame, they would hammer in nails spaced equally apart and tie lengths of string from one end to the other to create their rows and columns. Then the frame would be placed in front of the model or painting subject so they could look through the grid.
Throughout history many famous artists have used the Grid Method for drawing including M.C. Escher, Leonardo Da Vinci, Albrecht Durer, Van Gogh. Since the invention of the camera, the Grid Method has evolved to where artists print out a photo and draw their grid directly onto the photo or overlay it with transparent film then transfer the image block by block to the art surface.
It's all easy enough when the surface is flat like a canvas or building-side mural. But when the surface is contoured and cornered issues of perspective create huge mathematical problems so complex that they eventually have to be solved by the loving eye of the artist as much as by pencil and paper.