Land Use Mapping by Remote Sensing
Zhou Bomin
Since 1960’s being not satisfied with his with his perceptual knowledge on the physical elements of the Earth, man has progressed to learn the relationship between man and his environment, to know and control the dynamic laws governing the environmental changes and the changes of natural resources. China is vest in territory and rich inland resources, but the land shared by each person is rather less because of its large population and therefore the land resources are very precious. The further research and mapping of land resources series of the whole country are fundamental work of land management of China.
The paper will discuss and summarize some procedures and methods on land use map compilation by using remote sensing information.
I. Map-liked Processing of Remote Sensing Information
I. Mathematical Basis
A map should be a conformal projection, this is the say that all points within the map sheet are equally scaled, while an uncorrected remote sensing image is a multi-centered projection , all points with the picture are differently scaled. However it must be pointed out that an unrefined multi-characteristic demonstrated by the conformal projection, i.e. it has an approximate map projection. When wanted map materials lack and the same named object points can not be obtained for photograph rectification, the unrefined image can be expediently used as a map. A refined picture is generally controlled by the same-named object points can not be obtained for photograph rectification, the unrefined image can be expediently used as a map. A refined picture is generally controlled by the same-named object points and at least four such control points are selected for the purpose. The pixel plane needs to be displaced in order that the accuracy requirement set by the same kind of maps is to be meted. The projection difference caused by altitude difference of an object can be computed according to the equation dh=h/H.r.n., As a rule, the maximum projection deference of a pixel should be.
SSmaller than 0.5mm. Ordinarily, projection difference can be neglected in land use man compilation. After its geometric correction by pixel plane displacement, a remote sensing image can have the same mathematical basis and geometric accuracy as a map.
2. Symbol and Annotation System
Transmitting information by coordinate combination of symbols and annotions, a map is readable without any difficulty. Although remote sensing imagery is abundant in panoramic perpendicular images, it lacks relevant symbols and annotions and therefore it is necessary to introduce some special symbol and annotion system into the remote sensing imagery. For example, river images matched with their annotion, mountains and their peaks matched with their names and altitude annotation as well as unpicturable administrative boundaries or other linear symbols drawn complementarily etc. can make the remote sensing imagery to be integrated with both map characteristics and contents simultaneously.
