Sightline Analysis And Height Control

In the Urban Design, building height is an important control factor of its spatial form, which determines two spatial forms of the city:one is city's holistic external contour-the city skyline; second, internal spatial form and spatial scales of the city.Beijing and Xi'an is the main research object of this paper. As the first Chinese 24 famous historical and cultural cities promulgated since the founding of our People's Republic, they have already achieved some successes in the coincidence of city's development and protection. There are also mistakes and shortcomings among them.In the case study of this article, the method of visual science principle-visual analysis is be used. Visual analysis is almost the most scientific and rational means of city planning. It is a guideline to do the quantitative analysis of landscape propylaea, the city skyline, the city construction content around or amid the landscape node, and make the sensory cognitive of the city landscape measurable. Thereby, we can control the height, body mass, and the scale of historical architecture. Then give prominence to the historical city skyline and city's internal spatial scales which is comfortable for human actives. So we can achieve the objective of protect the historical and cultural city.But for a long time, in the historical city's protection planning and new city designing of China, the control technology was revealed simple and rough, also lack of scientific-basic quantification measure and data-base. In the basis of large amounts of data collected, through the analysis of visual propylaea, street scenic focal point, and city landscape line of Xi'an and Beijing, this article point out the method and theory shortcomings of architecture height controlling. Then in the epilogue of this paper, I give out several advices about the protection of the famous historical and cultural cities, and the methods to solve the problem of height out-controls.