Projective geometry

Projective geometry is a foundational part of modern geometry dealing with properties and principles that are invariant under projection transformations. Roughly it is the study of the shadows cast by geometric figures.
 Jean-Victor Poncelet France 1822 Projective geometry

Projective geometry is a foundational part of modern geometry dealing with properties and principles that are invariant under projection transformations. Roughly it is the study of the shadows cast by geometric figures.