This paper describes an algorithm for deriving line features generated by roads in forests from L-band synthetic aperture radar (SAR) images. The algorithm traces connected dark pixels successively, while avoiding meaning-less linear features generated by speckle and connecting interruptions in dark line features due to bright back-scattering from trees. The algorithm has been applied to L-band SAR images of the northern Yucatan Peninsula where a substantial amount of roads of the Maya Age are known to exist, and has operated satisfactorily.

抄録全体を表示

1) All of the ancient civilizations in the Old World were developed in the arid and temperate climates and their margins rather than the humid tropics. In as much as the establishment and maintenance of irrigation canals necessarily involve cooperation, and therefore a rather high degree of social organization, the conditions of the arid regions were exceptionally conducive to the establishment of the highly complex policies. While the ancient civilizations in the New World were developed under fairly similar arid condition. The “Hochebenentheori”, high plateau theory, that the ancient civilizations on the New World were originated from high plateaus of the tropics, has a strong resemblance to the origin theory of civilizations in the temperate climate of the Old World, as far as temperature is concerned. Thus the Hochebenentheorie should be recognized from the view of the milieu theory, as well as recognized through the organism of production developed on this environment. Then, how comes the fact that Mayan civilization was developed in the humid low land of the tropics?
2) When we examine the great achievements of Mayan civilization and natural environment in which they still remain, we can understand why some historian regards the causes of development of this civilization in this region as a mystery. It is doubtful that the ability of any race can establish it at present.
3) Therefore, if the physical conditions of Maya land were the same in the past as in the present, the ancient Mayas must have possessed a degree of energy and a power of resistance to the debilitating effects of a tropical climate far in excess of that of any other race now existing.
While Dr. Huntington's “Climatic Pulsation Theory”, which asserts the lessening of rainfall, means the diminishing of agricultural possibility that is contradictory to the possibility of support of great population in the Mayan Empire.
The “Extraordinary Capacity Theory” was only an unproved assumption, until, maintaining the “Hochebenentheorie”, Dr. Sapper explained by acclimatization the reason why extraordinary capacity of the ancient Mayas was constituted.
4) We would supplment Dr. Sapper's theory with the “Forced Labor Theory”. The Mayan community was under religious government. Religious forced labor promoted the aritificial selection of the ancient Mayas and provided them with the labor capacity in tropical low land. When the fall of the empire released the forced laborers, they could migrate to other places, seeking after the environments which they prefer and they lost their extraordinary capacity.

抄録全体を表示