$[$Projection$].$

Consider a camera located at $(1,2,3),$ and a $3$D point located at $(9,7,12).$ Coordinate is represented as $(x,y,z).$

a$)$ What is the projection of this point on $2D$ image plane, if we are using perspective projection with focal length $=5?$

b$)$ What is the projection when the focal length $=10?$

c$)$ What is the projection when we use orthographic $($parallel projection$)?$