THEORY:

Isometric projections enable an object to be viewed in three dimensions in a single view, from which the actual sizes can be measured.

When the projectors (ex: line of sight of humans) from the source are parallel to each other and perpendicular to the plane of the object, for example a person looking at building, then the projection is called as an Orthographic Projection.

Orthographic projection is used to represent three-dimensional objects into two dimension as shown in Fig 1. It is a form of parallel projection, in which all the projection lines are orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface. The obverse of an orthographic projection is an oblique projection, which is a parallel projection in which the projection lines are not orthogonal to the projection plane.