Projections

Projection is related to mapping. The different parameters to be taken care of while projecting an object are spatial relationship among the projectors that project the points on the object and the spatial relationship between the projectors and the view plane. There exist two methods of projection- perspective method and parallel method. In perspective projection method, idea is very much similar to that of an artist who prepares perspective drawings of three dimensional objects. Here eye of the artist is the center of projection and the plane containing canvas is the view plane. Image point is determined by a projector that goes from an object point to the center of projection. Two important terms in perspective drawings are vanishing points and perspective foreshortening. When the distance between object and center of projection increases, objects appear smaller. This illusion is called perspective foreshortening. Vanishing points are points where certain sets of parallel lines appear to meet. Parallel projection method is a common method usually employed by engineers. Here drafters are used to create drawings of an object with optimum scaling and shaping.