The points on the spherical grid are transferred to the cylinder which is then unfolded into a flat plane. When projected from the center of the globe with the normal aspect, the typical grid appearance for cylindrical projections shows parallels and meridians forming straight perpendicular lines. The spacing varies depending on the type of cylindrical projection. The projection process involves the transformation of the spherical surface onto a flat plane through tearing, shearing and compression of the sphere to make it lie flat. All map projections, thus, produce some forms of distortion of shape, area, distance, direction, or scale.
Distortions vary per map projection.
Various reference ellipsoids have been developed and used in different parts of the world for large scale mapping purposes. That is, at a given scale, for every part, as well as the whole, map area is proportional to the corresponding area on the Earth. Deformation occurs in elliptical fashion away from tangency thus shapes are distorted. The name arises from the fact that in the normal aspect of Cylindrical, Conic and Azimuthal projections the principal scale is preserved along the meridians and therefore all parallels on the map are equidistantly spaced. The science of earth measurement.