KoG, Vol. 6. No. 6., 2002.
Izvorni znanstveni članak
Shade Lines of Curved Surfaces - Rotational and Helical Circular Surfaces
Daniel Lordick
; Institut für Geometrie Technische Universität Dresden, Dresden, Germany
Sažetak
Typically a tangent t to the shade line e of a curved surface Φ is constructed by making use of the fact that t and the light ray l form a pair of conjugate diameters of the so-called DUPIN-indicatix of Φ at an investigated point P. This article describes a very different approach to developing such a tangent: The shade line e is defined as the intersection of Φ and a special ruled surface Ψ, which depends both on Φ and on the bundle of light rays. Ψ is introduced as accompanying ruled surface along e. This approach allows a simple, linear and globally applicable construction of t for rotational and helical surfaces by means of descriptive geometry. The method is also suitable for translation surfaces as well as for central illumination [4]. In a few cases Ψ is a ruled quartic.
Ključne riječi
curved surface; Dupin-indicatrix; ruled surface; shades and shadows
Hrčak ID:
3924
URI
Datum izdavanja:
17.2.2003.
Posjeta: 1.720 *