as such is used together with other tools, which are either integrated modules or stand-alone products, such as: Computer-aided engineering (CAE) and finite element analysis (FEA, FEM) Computer-aided manufacturing (CAM) including instructions to computer numerical control (CNC) machines Photorealistic rendering and motion simulation. Document management and revision control using product data management (PDM) CAD is also used for the accurate creation of photo simulations that are often required in the preparation of environmental impact reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like, where the proposed facilities are allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD. Using four properties which are history, features, parameterization, and high-level constraints are helpful in everyday engineering. The construction history can be used to look back into the model's personal features and work on the single area rather than the whole model. Parameters and constraints can be used to determine the size, shape, and other properties of the different modeling elements. The features in the CAD system can be used for the variety of tools for measurement such as tensile strength, yield strength, electrical, or electromagnetic properties. Also its stress, strain, timing, or how the element gets affected in certain temperatures, etc. Types There are several different types of CAD, each requiring the operator to think differently about how to use them and design their virtual components in a different manner for each. 2D CAD There are many producers of the lower-end 2D systems, including a number of free and open-source programs. These provide an approach to the drawing process without all the fuss over scale and placement on the drawing sheet that accompanied hand drafting since these can be adjusted as required during the creation of the final draft. 3D CAD 3D wireframe is basically an extension of 2D drafting (not often used today) into a three-dimensional space. Each line has to be manually inserted into the drawing. The final product has no mass properties associated with it and cannot have features directly add to it, such as holes. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow using the wireframe model to make the final engineering drawing views. 3D "dumb" solids are created in a way analogous to