Computer-aided design is the use of computer software to create drawings. Today the vast majority of technical drawings of all kinds are made using CAD. Instead of drawing lines on paper, the computer records similar information electronically. There are many advantages to this system: repetition is reduced because complex elements can be copied, duplicated and stored for re-use. Errors can be deleted, and the speed of draughting allows many permutations to be tried before the design is finalised. On the other hand, CAD drawing encourages a proliferation of detail and increased expectations of accuracy, aspects which reduce the efficiency originally expected from the move to computerisation.
CAD programmes, for example the worldwide market leader AutoCAD, are complex and require both training and experience before the operator becomes fully productive. Consequently skilled CAD operators are often divorced from the design process. There are other more basic programmes such as SketchUp that allow for more intuitive drawing and are intended as a design tool.
CAD is used to create all kinds of drawings, from working drawings to photorealistic perspective views.Architectural renderings (also called visualisations) are made by creating a three-dimensional model using CAD. The model can be viewed from any direction to find the most useful viewpoints. Different software (for example Autodesk 3ds Max) is then used to apply colour and texture to surfaces, and to represent shadows and reflections. The result can be accurately combined with photographic elements: people, cars, background landscape.
An architectural animation is a short film showing how a proposed building will look: the moving image makes three-dimensional forms much easier to understand. An animation is generated from a series of hundreds or even thousands of still images, each made in the same way as an architectural visualisation. A computer-generated building is created using a CAD programme, and that is used to create more or less realistic views from a sequence of viewpoints. The simplest animations use a moving viewpoint, while more complex animations can include moving objects: people, vehicles and so on.