IMAGING OF A HYPERBOLIC PARABOLOID WITH TOUCHING LINE WITH THE PARABOLAL WRAPPING CONE

Abstract

The paper is dedicated to architectural structures modeling by means of computer-graphics. Images on the monitor represent perspective. That’s why the images could be assessed from the most convenient points as viewer’s position is considered to be the perspective center. Non-rectilinear profile makes the structure the most impressive. The hyperbolic paraboloid surface is researched. Parabolas and hyperbolas are the only forms of its sections except for tangent planes cases. Parabolas as contact lines are reviewed. Hyperbolic paraboloid is an infinite surface that’s why only a portion of it could be modeled. Four link space zigzag ({4l} indicator) is its best representation. In such case the non-rectilinear profile should be represented as a curve of second order semicircular arc. Modeling of a limited section does not affect the final modeling because the {4l} representation makes the depiction of all surface in that frame of axis that have the identified hyperbolic paraboloid looks like a cone. The paper’s objective is development of imaging technique using parabolic contact lines to design hyperbolic paraboloid surface and applicable to several surfaces of the same construction. To do so, parameter analysis of the task is conducted, the applicable theory is identified, and the hyperbolic paraboloid imaging technique using the set profile line in the form of any curve of second order is conducted, namely the imaging technique for contact parabola and the set of hyperbolic paraboloids which it set forth. The set of plans that may contain the parabolic contact line set is two-parameter. However, in general, the position of those planes is remains unknown. Thus, the task is as follows: find the third point of the plane that intersects the given wrapping cone along the parabola when the two points are given. These two points must belong to the same forming line on the cone. The imaging requires 7 parameters whereas the hyperbolic paraboloid has 8 parameters. That’s why with one parabolic contact line and given wrapping cone of the second order one-parameter set of hyperbolic paraboloids could be imaged. The paper shows how to image the contact line if the profile line is given as a parabola, ellipse, or hyperbola. The portion of one hyperbolic paraboloid may imaged when the parameters are aligned and any other bisecant of same perspective line of shape. Two portions of parabola conjugated due to the joint wrapping cone hyperbolic paraboloid imaging is demonstrated.