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The comprehensive analytical mapping on the Chinese territory satelite

Fu Suxing
Institute of Geography, Chinese Academy of Sciences
Beijing,China


Abstract
The article mainly expounded the Territory Satellite images mapping characteristics and the technical standards for the applications. Because the images got with the scanning angles of + 42 degrees, which can generally be used for thematic series mapping and can accord well with the precises demanded. The article has analyzed the comprehensive applications of multiple information, such as the thematic series mapping on the hydrology utilization of land resources, agricultural fields with middle-low yields , forest resources ,tourist resources , changes of natural environmental elements, regionalization of pre-Cambrian metamorphic rock, and evaluation of regional engineering stability. The practical investigations show, that the Territory satellite images combined with other remote sensing data is a new technical method for us to draw the analytical thematic maps at high level.

The Territory Survey Satellites (Territory satellite) were lunched in October 1985 and October 1986 respectively, and the territory images covering all-over the country have been acquired. The thematically application studies have been conducted by selecting more than ten typical regions including the Beijing-Tianjin-Tangshan region, the Huanghe River delts, etc. The various achievements have been gained by the studies on these regions. This marks that the aeronautical and remote sensing technology of China has reached a new level and has the capabilities to serve the nation in land reclamation and national economic construction. Starting out of practical use, the application studies of the territory images of resources and environment in the Beijing-Tianjin-Tangshan region have overcome the restrictions of specific thematical investigation, have studied the various thematics and conducted the series mapping at scales of 1:250,000 and 1:500,000. Meanwhile, the related databases have been set up.

Researches on the territory images and their mapping charateritics
The panoramic images acquired by the low-orbit Territory Satellites of China have the merit features such as the high resolution, identified layers, etc. In the central part of the image the scale ranges between 1:200,000 and 1:230,000; around the central part outwards the scale gradually becomes smaller with the increasing satellite heights and scanning angles. The applicable technical standards have been proposed through the analysis of scanning angles, theoretical calculation and practical approval of sample tests.

Taking ±20 degrees as its scanning angle, they are the two zones on the two sides of the central part with a width of 45cm respectively. With small distortion and clear layers, they can be used for the thematic interpretation and, mapping at scales of large of medium. When the scanning angles are ±42 degrees, they are the images between ±21 ---±42 degrees. With relatively great distortion, decreased resolution and smaller scale, the images can only be used for the analytical mapping at a scale of 1:250,000. When the scanning angles fall between ±42--±60 degrees, it will be difficult the precise of thematic mapping, we have developed the geometric rectification software package that this combined the light beam method, the finite element method and with auxiliary parometers; we have researched the Territory satellite orthographic images of an extended region. Their rectification accuracy (with a mean error of about 55m for a point area) is more than one times than employing the multinomial method only.

Analytical thematic interpretation and series mapping
The Beijing-Tianjin-Tangshan region is a developmental and constructional area with a high research level. Provided with a great deal of scientific data, to carry out the regional comprehensive thematic mapping by using multi-data of the Territory Satellites remote sensing is an important method for the analytical remote sensing mapping.
  1. Analysis and mapping on the Hydrological Ground
    The hydrological ground is a geographical-geological element which influences and controls the formation, migration, storage and quality of water resources. According to the factors exerting influences on the quantity of water resources, the hydrological ground map was synthetically compiled on the basis of the remote sensing data of the Territory Satellites and other aerial photographic methods, such as the maps of morphological elements, litho logical types, vegetation covers, etc. The classification of these elements maps was mainly based on the leading factors which directly or indirectly influence the yields of water resources. The classified types are named as, for example, moderate vegetation cover-crystalline rock-middle mountain, and the like . Such, on the basis of the hydrological ground, the plenty of data acquired by the normal experiments can be organically combined with the types of hydrological ground, furthermore, the calculation parameters of different hydrological ground can be given regularly, and the quantity of water resources in a peculiar region can be calculated out through the concerned mathematical models. The experimental results by this method are very appropriative to those by the normal calculation. This makes us believe that the method has the broad future for application with the progresses of identical techniques for numerical images and the computer-assisted mapping, and with the supportes provided by the GIS

  2. Analytical Mapping for land Utilizations
    The concentrated large and medium-sized cities, dense population, developed industries and minings, vigorous tourism, all of these have rendered new relationships between the structures and proportions or urban and rural land uses. In view of this practical issue, the interpretation mapping can be accomplished by full use of the clear identities of non-agricultural land elements, such as settlements, water bodies , transports , industrial and mining sites. Taken as an example, the urban residential area can be marked by the authentic shapes in the images, this can not only reflect the distribution density of urban residential areas in the region, but also be helpful to calculate their areas occupied . Through the analysis on the non -agricultural land in the images, and the implementation of the measurement technology of bi-reducing parometers, the various data of land uses can be obtained on the unit of county. Then the data were input into a computer and the second data was analyzed for mapping . The maps accomplished are the index map of land background -development level, the map of building area per capita.

  3. The Map of Agricultural Middle -Low Yield Land Types
    The characteristics of land quality can not conspicuously show in the present land use map, but quality characteristics of badland and degenerated land can be demonstrated to some extent in the remote sensing imageries. By means of the regional differentiate laws among various eco-environmental relations. Hence, the analytical mapping on the saline-alkali soil, depression waterlogged field, shifting-sand area, polluted land, are the very important measures for middle low yield lands improvement. Those types of land, can generally be analyzed according to their images colors and the related marks. For instance, the erosion land can be divided into different erosion grades by geo-related analysis on the densities of water systems and gullies, the coverage of vegetation, human producting activities, etc. While, the erosional land's distribution is closely related with the shifting-sand land.

  4. The Investigation Mapping on the Forest Land and the Land Suitable for Forestry
    The major forests distributed in the region are natural secondary forests and artificial forests. It is of great significance to survey the forest resources, especially the distribution of the land suitable for forestry applying the geoscientific and biological principles of remote sensing. The division and interpretation of the land suitable for forestry are mainly made on the basis of its eco-environmental conditions, indicator plant communities, as well as imageries features. For example, mountain deciduous shrubberies are an important indicator community of the land suitable for forestry, they reflect the different eco-environmental conditions: mountain meadows are also an indicator community of the mountain land suitable for forestry, particularly for temperate forest; besides , lowland meadows, halo-vegetation, sandy vegetation are all the indicator communities of the plain land suitable for forestry. The total area of the land suitable for forestry was calculated about 860,000ha accounting for over 15% of the total land area. There for, great emphasis must put on to construct the land suitable for forestry for the forestry for the purposes of developing forestry and improving eco-environment of the region.

  5. Analytical Mapping on the Scenic Tourist Resources
    With the help of the particular information provided by the remote sensing on natural landscapes, such as grotisque peaks and fantastic stones out of granite, mountain landscape of magma tic rock, meanders and gullies in carbonate rocket. the scenic tourist resources, concentrated in Beijing, have been divided into 13 tourist areas . The remote sensing analysis shows the master of the scenic differentiation laws in a particular region is the important theory and method for the researching on the mapping of natural scenic tourist resources.

  6. Analysis and Mapping on the Changes of Natural Environmental Elements .
    The natural elements of the continent-sea distribution, river and lake systems, forest vegetation, etc. in the region have changes dramatically during the last near 10,000 years. While the structural arrangemental superpositon and mosaic relation between these elements are all reflected in the images to certein extent, so, we can analyze their space-time distribution patterns, evolution characteristics, furthermore can analyze their evolution sequence and development level. One example is the four changes of the Luanhe River system are respectively demonstrated in the images ; another is the zonally extended plains in the region for the earth crust's uplift-depression movements and accumulative mechanism plain and coastal plain from the northwest to the southeast to the southeast. During the last decades, the circular structure concentrated at large cities has developed persistently with the rapid urbanization and the spreading of city proper. Using the high resolution images, the analytical mapping on them can be conducted through dynamic analysis, studies on the changes of functional structures of cities.

  7. The Regionalization and Mapping of the Metamorphic and Structural Lithofacies
    The construction of the regional structural frame and the definitions and mapping of the structural lithofacies through the analysis of the linear structures in the imageries and the identification of the image indicators of metamorphic iron ores' controlling structures through the investigations on the circular structures are the new approaches are the new approaches to survey the metamorphic mineral resources of the pre-Cambrian.

  8. The Evaluation and mapping on the Regional Crustal Stability
    According to the maximum streets direction and the maximum dangerous slipping angle, and the liquiferous degree of sandy soil, the Beijing-Tianjin-Tangshan region can be divided into the stable, relatively stable and less stable areas. The maximum dangerous slipping angle were determined through the investigations on the linear structures and their jointing relations in the images, taking the references to other geological and geophysical data, and supported by survey data of strain-stress in the region.
Conclusions
  • The investigations on the Territory Satellite images of the Beijing-Tianjin-Tangshan region have first proposed their applicable technical standards. Generally speaking, the images with their scanning angles within ±42 degrees are suitable for the thematic series mapping at scale of 1:250,000.
  • To apply the data of the Territory satellite and other remote sensing data with the assistance of the multi-information supplied by geophysical and other geoscientific data, to employ the analytical theories of remote sensing-geosciences, are the important technical methods for us to analytically conduct the high level thematically series mapping.
  • To make advantages of the mapping achievements of remote sensing analysis and the calculated data of resources quality, through setting up the database , is the technical guarantee for us to renovate the data and make second development of them, as well as to draw maps at a high level.
  • To develop the application of satellites, make us to carry out the investigations on the applied systems and their intelligence of China's resources satellites. Which are the key to develop the geosciences, environmental science and information science as united high technology. This will show that China'sd remote sensing researches in the fields of resources and environment have stepped up to a new application level.