thought, for trying different ideas quickly. Choice becomes sharply reduced once the design is committed to a scale drawing, and the sketch stage is almost always essential. Diagrams are mainly used to resolve practical matters. In the early phases of the design architects use diagrams to develop, explore, and communicate ideas and solutions. They are essential tools for thinking, problem solving, and communication in the design disciplines. Diagrams can be used to resolve spatial relationships, but they can also represent forces and flows, e.g. the forces of sun and wind, or the flows of people and materials through a building. An exploded view diagram shows component parts dis-assembled in some way, so that each can be seen on its own. These views are common in technical manuals, but are also used in architecture, either in conceptual diagrams or to illustrate technical details. In a cutaway view parts of the exterior are omitted to show the interior, or details of internal construction. Although common in technical illustration, including many building products and systems, the cutaway is in fact little-used in architectural drawing. Types Architectural drawings are produced for a specific purpose, and can be classified accordingly. Several elements are often included on the same sheet, for example a sheet showing a plan together with the principal façade. Presentation drawings Drawings intended to explain a scheme and to promote its merits. Working drawings may include tones or hatches to emphasize different materials, but they are diagrams, not intended to appear realistic. Basic presentation drawings typically include people, vehicles and trees, taken from a library of such images, and are otherwise very similar in style to working drawings. Rendering is the art of adding surface textures and shadows to show the visual qualities of a building more realistically. An architectural illustrator or graphic designer may be employed to prepare specialist presentation images, usually perspectives or highly finished site plans, floor plans and elevations etc. Survey drawings Measured drawings of existing land, structures and buildings. Architects need an accurate set of survey drawings as a basis for their working drawings, to establish exact dimensions for the construction work. Surveys are usually measured and drawn up by specialist land surveyors. Record drawings Historically, architects have made record drawings in order to understand and emulate the great architecture known to them. In the Renaissance, architects from all over Europe studied and recorded the remains of the