tailieunhanh - Lecture Autodesk inventor: Perspective projection

Lecture Autodesk inventor: Perspective projection. The main contents of the chapter consist of the following: perspective projection characteristics, perspective sketch, classes of perspective projection, vanishing points, one-point perspective, two-point perspective, three-point perspective,. | Perspective Projection Perspective Projection Characteristics Center of Projection (CP) is a finite distance from object Projectors are rays (., non-parallel) Vanishing points Objects appear smaller as distance from CP (eye of observer) increases Difficult to determine exact size and shape of object Most realistic, difficult to execute Not used so much for engineering documentation Important in Computer Graphics Perspective Sketch Horizon – observer’s eye level Ground Line – plane on which object rests Vanishing point – position on horizon where depth projectors converge Projection plane – plane upon which object is projected Classes of Perspective Projection One-Point Perspective Two-Point Perspective Three-Point Perspective View from Above Vanishing Points Object edges parallel to projection plane remain parallel in a perspective projection Object edges not parallel to projection plane converge to a single point in a perspective projection vanishing point (vp) Vanishing point of a principal axis principal vanishing point (pvp) One-Point Perspective One principal axis cuts projection plane one principal vanishing point Projection plane parallel to one principal plane object image Two-Point Perspective Two principal axes cut projection plane two principal vanishing points Projection plane parallel to one principal axis object image Three-Point Perspective Three principal axes cut projection plane three principal vanishing points Lateral Movement of CP Varying Distance from CP Projection Plane Location Size of projected image depends upon location of projection plane with respect to object Vanishing Points Revisited A vanishing point is found by passing a line through the center of projection, parallel to a set of parallel object edges. The point where the line pierces the projection plane is the vanishing point. object image Perspective Projection The . | Perspective Projection Perspective Projection Characteristics Center of Projection (CP) is a finite distance from object Projectors are rays (., non-parallel) Vanishing points Objects appear smaller as distance from CP (eye of observer) increases Difficult to determine exact size and shape of object Most realistic, difficult to execute Not used so much for engineering documentation Important in Computer Graphics Perspective Sketch Horizon – observer’s eye level Ground Line – plane on which object rests Vanishing point – position on horizon where depth projectors converge Projection plane – plane upon which object is projected Classes of Perspective Projection One-Point Perspective Two-Point Perspective Three-Point Perspective View from Above Vanishing Points Object edges parallel to projection plane remain parallel in a perspective projection Object edges not parallel to projection plane converge to a single point in a perspective projection vanishing point (vp) Vanishing point .