In oblique projection, object is assumed to be placed with one face parallel to plane of projection and receding lines are drawn from faces parallel to projection plane and or parallel face.

The distance points are equidistant from center of vision distance of each from centre of vision being equal to distance of station point from picture plane perspectives of all horizontal lines inclined at 45 degrees to picture plane converge to a distance points on horizon line.

In a visual-ray method, points on perspective are obtained by projecting top view and eir front view or side view of visual rays. In addition to top view of visual rays, use of vanishing points of straight lines is made in Vanishing point method.

In perspective projection, point where eye of observer is located while viewing object is called station point and distance of station point from picture plane, when taken equal to about twice greatest dimension of object gives good view in perspective.

For large objects such as buildings, station point is usually taken at eye level of a person of about 1.8 meters. For small objects, station point should be fixed at such a height which gives good view of top faces and side faces.

When receding lines are drawn to half size scale n oblique projection is cabinet projection. When receding lines are drawn to full size scale n oblique projection is cavalier projection.

The station point in anywhere from picture plane if a circle is placed in any angle with ground plane in maximum possible critical position perspective of circle will always be an ellipse.

In perspective projection, line in which horizon plane intersects picture plane is called horizon line. It is parallel to ground line. And point in which perpendicular axis pierces picture plane and lies on horizon line is called center of vision.

Curve of any shape can be drawn in perspective by enclosing it in a rectangle and n drawing horizontal and vertical lines through a number of points on curve similar to a circle which is enclosed in square.

Oblique projection is a specified projection which is used for making an assembly of an object and provides directly a production drawing of object for manufacturing purpose.