3D rendering allows the viewing of one or more objects in a real world perspective. The crane support shown is an example  of how a structure   would look when it is built.  Colors are applied to highlight the different components.  For a true image, textures can be applied such as aluminum, brass, copper etc. and lighting added to give the appearance of a photograph of a real object.

Photo-realistic renderings are time consuming and usually reserved for use in proposals and bidding.  However these renderings are often used to display a product without the cost of producing the product.  The product can be shown long before production begins.

The 4 pictures in this page are the 3D rendering models of kerosen heater KSP-229.