Browsing by Author "Chang, YX"

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Physically-based patination for underground objects
(2000)
Chang, YX
;
Shih, ZC
;
資訊工程學系
;
Department of Computer Science
Although current photorealistic rendering techniques can produce very impressive images, the rendered objects are often too clean and shiny. Thus, the resulting images look unnatural. This paper proposes a physically-based model to simulate the appearance of patinas on ancient Chinese bronzes. Buried in the soil for thousands of years, many patinas are found on the surface of ancient bronzes as a result of the aging process and the physical and chemical conditions of the soil environment. The development of patinas is modulated herein by L-systems according to tendencies based on the environmental factors and object geometry. The tendencies are employed to represent the accumulative effect of all factors on patination. The proposed model can be extended to simulate a variety of metallic patinas including the ancient Chinese bronzes discovered at San-hsing-tui, Sichuan, China.
The synthesis of rust in seawater
(2003-03-01)
Chang, YX
;
Shih, ZC
;
資訊工程學系
;
Department of Computer Science
Computer graphics researchers have recently revealed that the presence of imperfections is an essential part of the illusion of photorealism. An improved model to simulate the rust development of ferrous metals in seawater is proposed. The tide and the current, under the gravity of the sun and the moon, affect the stability of the environment at the bottom of the ocean. A simple current model is employed to elucidate the periodic transition of currents in the ocean. L-systems, coupled with the current model, modulate the diffusion of rust according to tendencies based on the object geometry and environmental factors. Changing the underlying distributions of tendency allows images of a variety of metallic rusts to be generated.