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Poster Session Q
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The use of OR method and establishment of data bank in Land Resource Survey
Chen Xi
Huangyan City Land, Administration Bureau, Zhejiang, China
In 1984, Ke Zhengyi, a vice professor from zhejiang Agricultural put forward OR method, a new way dealing with geographic information of remote sensing by which he developed the Data System of land resource survey under the leadership of Chain national Land Administration Bureau. This system passed technical trusts in February, 1991. It has found out a new economy and easy way for China and other developing countries to establish land information systems on a large scale.
The Data Processing System Of Land Resource Survey, with advanced technological ways and strong data processing ability, is an advanced tool to deal with land resource survey results with computer in ways of vertical correction, area calculation, statistics and picture drawing, etc. The system needs a high quality of operating technique and equipments. When the system is put into actual use, it will happen some troubles on operator’s quality, efficiency, costs and quality of products for tacking of actual widespreading experiments.
In order to fulfill tasks of data processing in Huangyan city’s land survey and put the system into use as early as possible for the oncoming national land survey, Huangyan land Administration Bureau has set up the land survey computer center and researched into some difficulties and problems which probably happen in the course of large-sized use. After one year’s experiments we have improve and enhanced the system, and formed a complete set of management regulations including technical operating system, quality guaranteeing system and organizing measures to meet demands of use on a large scale. Meanwhile we have finished tasks of data processing. of Huangyan Land Resource Survey successfully and established data bank of Huangyan City’s land resource.
This article, based on experiments of Huangyan land survey data band, emphasizes on difficulties and problems which probably happen in the course of use of the system, technical method s and managing measures to solve these problems, and ideas of improving land information system with OR method continuously.
The current situation of use of Huangyan City’s land resource
Huangyan city is located in the coastal zone of Mid-Zhejiang. It has an area of 1, 313. 60 square kilometres including 56 percent of mountain and hill, 44 percent of plain and seashore with a favourable weather Huangyan is abundant of
fruits like oranges, loquats, red bayberries, etc. It is very difficult to survey land resources because of manifold lands and complicated current situation of use.
In August, 1989 we began surveying for current situation of land resources on the basis of new airphotos with a scale of 1: 10000. In accordance with the Technical Standard Of Survey For Current Situation Of Zhejiang Provincial Land Resources, we divide types of land resources into 3 grades, 84 kinds, with village as a basic unit.
It is the best survey for land resources in Huangyan’s history which features the richest contents, completes detailed division and highest precision. In order to finished next tasks such as hand vertical sketching, measuring area, statistics and compiling thematic maps, we decided to make full use of the System. In july, 1990 we established Huangyan Land Resources Survey Computer Center and bought a complete set of equipments. Meanwhile we employed two technicians and eight operators. After one year’s exploration and research we have solved one series of problems which arisen from large widespreadings, and completed preparation for establishing Huangyan Data Bank Of Land Resources Survey.
The use of OR method
A method so-called OR can substitute the hand vertical sketching and area measuring by Ortho-Rectifying the unit edges upon the identified airphotos and makes thematic mapping as well as area computing be implemented automatically tyby system itself. Digital rectification of identified edges of airphoto is more complicated compared with that of space picture. It can be solved by using the following collinear equation under the condition of vertical aerophotography ( till angle < 3).
where
f is focal distances of aerial camere.
F,w,k,X c,Y c, Z c, are elements of exterior orientation.
x,y are plane coordinates of image point in fiducial coordinate system.
X,Y are plane coordinates of corresponding object points in object space coordinate system.
Z is elevation of obkect point.
f is a constant and can be found out in direction of aerial camera.
The coordinates of the points of interpreted edges of space pictures will be transformed automatically into those of thematic map after interpreted unit.
edges of space pictures are digitized and a polynomial is set up by using corresponding relationship between obvious points both in space picture and standard topographic map, in the same time, thematic maps can be output by using package of CAC, and the unit area can be calculated in coordinates of the polygon’s vertexes. Procedure of OR method is as follows:
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