Final answer:
In a multi-view orthographic projection, a surface shown as a true shape and size in one view and lines in other views is called a principal surface. Orthographic projections are utilized in engineering and technical drawing to provide accurate representations of objects from multiple perspectives without perspective distortion.
Step-by-step explanation:
In a multi-view orthographic projection, a surface that is seen as a true shape and size in one view and lines in other views is called a principal surface. Orthographic projection is a method where different views of an object are projected onto planes that are perpendicular to each other.
Typically, there are three planes known as the top, front, and side views. Since these projections are on planes that are orthogonal to the directions of sight, they don't exhibit the distortions found in perspective drawings, where objects become smaller as they recede into the distance. However, linear perspective uses orthogonal, which are lines that converge at the vanishing point to create an illusion of depth on a 2D surface. On the other hand, atmospheric perspective depicts objects farther away as blurrier and less distinct. Nonetheless, in orthographic projections, principal surfaces are depicted as they are in reality but only from the view where they are most perpendicular to the viewing plane, presenting a true shape that is not distorted by angling or perspective.
Within the practices of technical drawing and engineering, the ability to create and interpret orthographic projections is a foundational skill. These projections are critical when it comes to turning ideas into detailed plans for manufacturing or construction. The depiction of the real image, as referenced in the question, is something that artistically can be somewhat replicated in perspective drawings, even though the term 'real image' is more technically used within optical systems, like lenses and mirrors in optics.
A real image in optics is the image that can be projected onto a screen because the rays physically meet at the image's location. Although in orthogonal projections, surfaces are depicted in a way that represents true shape and size without the need for rays to converge for this to happen, understanding how a real image is formed, as in the eye or a camera, can give insight into the principles of accurate representation in technical drawings.