A Means of Drawing for Perspective Ellipse and its Applications
There is no fixed form for circles not parallel to drawing, with the lens ellipse, and perspective ellipse changes with the size of circle, distance from the screen angle and the relative location of sites location. It is a hardful thing both for manual and for computer graphics. A mathematical model procedure is developed according to the perspective transformation, as long as inputting size of circle, distance from the drawing (coordinates) to the relative angle, as well as site location (coordinates), other parameters to determine the size, and the direction and position of perspective ellipse is determined.
Guozhong Chai, Congda Lu and Donghui Wen
X. F. Yu et al., "A Means of Drawing for Perspective Ellipse and its Applications ", Advanced Materials Research, Vols. 102-104, pp. 79-82, 2010