The people who prepare maps are called cartographers. A cartographer is someone who creates, designs, and revises maps, charts, plans, three-dimensional models, and spatial information databases, often using computer-based techniques, and applying principles of science, artistry, and technology. They determine map content and layout, as well as production specifications such as scale, size, projection, and colors, and direct production to ensure that specifications are followed. They also inspect final compositions to ensure completeness and accuracy, revise existing maps and charts, make all necessary corrections and adjustments, and compile data required for map preparation, including aerial photographs, survey notes, records, reports, and original maps.