An outline of The Science And
Technology on Remote Sensing of the People’s Republic of China
Chen Weijiang The State Scientific and, Technological Commission, P.R.C. China is a country of vast territory, diversified relief and rich resources. In order to check up on and manage the regenerated and unregenerated resources and monitor the environment in our country, all departments of our government have paid great attention to the development of the remote sensing science and technology which is a modern science and technology with brilliant prospects. As early as 50’s a specialized flying unit was organized to conduct aerophotography with a coverage of the major part of our territory. The initial use was made of aerial photos in draughting maps, conducting the experiments of regional geological survey and the investigation into the forest resources prospecting for petroleum, and selecting railway routes and the sites of large projects and so on. Since 70’s a sa result of the rapid dev elopment of remote sensing technology at the intenational level and the initial application of electronic optical and computer techniques to remote sensing in our country a gratifiying progress has been made in the remote sensing technology of our country, i.e. from the general visible black-white photography to modern remote sensing technology thus greatly changing remote sensing features of our country. Now our country has carried out the experimental application of colour photography black-white and false-colour infrared remote3 sensing photography and multiple-spectrum remote sensing. It is the same with image interpretation and processing techniques i.e. from the general developing and enlargement to color composite and image enhancement; gradually from visulal interpretation and simple optical processing to computer processing. A first step has been taken to use air-borne remote sensing and satellite remote sensing images in national economic departments for experimental purposes. The relevant scientific institutions and productive units in our country have paid attention to the development of aerial sensors and have got some results. In recent years, we have successively developed multiple-spectrum cameras and scanners and infrared scanners all of which have acquired vivid single spectrum black-white images and multiple-specrum color composite images in test flights. It is true of the development of microwave remote sensing such as several microwave radiators of different bands which have acquired data and images in test flights. The initial success in developing these sensors and their further perfect will make possible the establishment of sensor system in the field of aerial remote sensing of our country and the provision of basic means for aerial remote sensing carried out in all departments concerned. As for interpretation instruments we have developed density slicing units colour compositers optical processing equipments optical mechanical scanning devices for image output and input. We have conducted researches on geometric correction for margin and ratio enhancement of image processing and other techniques and have done preliminary experiments on home-made minicomputers and have attained some experiences. Presently we are setting about developing a complete image processing system. The scientific and higher-learning institutions is our country also pay much attention to researches on the fundamental remote sensing theories and the spectral characteristics of objecsts on the ground and therefore can provide scientific basic for selecting optimum bands of sensors and doing quantitative and qualitative analyses of image processing in the future. We have successively developed several types of geospectral radiators of single and dodudbdle optical channel with the measurement scope extending to near infrared bands. Now we are drawing up unified specificatio0n of measurement, setting up ground test bases and carrying out the measurement of recorded radiation characteristics of objects on the ground from which we have got an amount of data. Meanwhile our scientific institutions have done some initial researches on the characteristics of atmospheric propagation and radiation. In the filed of remote sensing application the relevant departments in our country have started to use satellite and aerial phots combined with ground investigation of typical regions in the following aspects such as regional geological survey petroleum exploration mineral reconnaissance hydrographic and forest resources survey seismics meteorology oceanography and environmental control. In recent years the relevant departments in our country have successively conducted comprehensive and specialized remote sensing experiments in some regions. The practice has proved that remote sensing is one of the approaches to prospect for and manage the natural resources of our country. The application of remote sensing in our country covers the following aspects: 1. Regional geological survey The industrial departments in our country have made use of satellite images in medium and small-scale geological mapping. This method has yielded good results in areas where so far a serious study on relief has not been made saving manpower and raising the precision of the maps. Compared with ground survey the compilation of geological maps by means of satellite photos together with serial phots has the advantage of greatly shortensing the mapping period raising productive efficiency reducing the cost and the intensity of labour and representing the hollow relief better. Along with trhe raising of interpretation level remote sensing techniques still have a fair potential in this field. 2. Hydrographic geological survey By the use of infrared aerial remote sensing we can get clear pictures of ground water ancient river courses spring sports subterrainean streams in karst regions and geothermal sports. Some departments in our country have started to use this method to find water. By means of satellite images we have revised the number and dimension of the lakes formerly surveyed and mapped not up to the specified standard precision and have found out the source of Changjiang river the longest one in our country so that we know it is 580 kilometers longer than know before. 3. Seismic geology The use has been made of satellite and aerial photos in doing researches on the geological structure background causing earthquakes. The seismic research institutions in our country have compiled the maps of nationwide geologica structure and activities and have done experiments on infrared remote sensing of the conditions after earthquakes in seismic areas and have got useful materials. 4. Engineering geology Using satellite and aerial photos we have analyzed geological structure and bad geological phomomenon thus providing data for the selection of the sites or routes of large projects. 5. Forest sources survey The main work we are doing now in this field is to use aerial photos to survey the forest sources and compile forest maps. We have found the aerial photos are an effective means to keep surveillance on forest fires. Recently we have also got gratifying results in the experiments of using satellite photos to prospect for forest resources in some areas. 6. Soil resources check-up It is very difficult to use conventional approaches to check up on the area of soil resources in our country. Now we are using satellite and aerial photos to measure the area of our soil resources which will provide data for dividing agricultural regions of our country. 7. Meteorological remote sensing We have acquired useful information of cloud charts in receiving data from meteorological satellites with receiving devices of synchronous and polar-orbit satellites thus we can announce weather forecasts and hurricane alarming in time. 8. Marine remote sensing Experiments are made on using satellite photos multiple-band infared and microwave remote sensing to keep surveillance on sea current offshore terrain coastal geomorphological characteristics allocation of estuary deposit and soil pollution of harbours. 9. Satellite photo maps The surveying institutions in our country have used satellite images to compile single colour maps at the scale of 1: 1000,000 an d satellite colour photo maps at the scale of 1: 500, 00 to be used by various departments. The above-mentioned examples of remote sensing applications show clearly that our applications are experimental in a certain extent even though some results have been got in this filed. As a rule they are limited to static analyses mainly through visual interkpretation. In order to apply remote sensing to all mational economic departments and make it a practical means we should make greater efforts than before. We plan to set up a Landsat ground receiving station in Beijing whose coverage is nearly nationwide. This station can acquire a staggering amount of information every day after completed. How to use these data to serve national economy is an arduous task facing all applied departments. With a view to promoting the development of remote sensing technology in our country and training personnel for all applied department the relevant institutions of higher learning and scientific research in our country havwe organized several kinds of remote sensing training courses which fostered more than 2000 scientific and technical people of different levels compiled several teaching materials and shot a scientific and educational film about remote sensing. These institutions are cultivating research students of remote sensing. In China many departments are engaged in remote sensing technology among which are the Academy of Sciences of China the Ministries of Geology Education Agriculture, Forestry, Metallurgy, Oil National Bureau of Surveying and Cartography. State Marine Bureau and so on. Throughout the country 100 institution or so engage in the research education and application of remote sensing. The Academy of sciences of China is mainly responsible for sensors fundamental theories on remote sensing and the development of remote sensing research; the Ministry of Geology is one of the early leaders in researches on remote sensing and equipped with a certain number of planes and sensors in its Geological Remote Sensing Center and has the capability of providing service to other departments; the Ministry of Education is mainly responsible for training personnel of remote sensing and in the meantime engages in the researches on the fundamental theories and applications; the National Bureau of Surveying and Cartography is in charge of the nationwide aerophotography and the reproduction of satellite photos of the whole country for all departments. The State Scientific and Technological Commission is responsible for the organizational management and coordination of remote sensing technology throughout our country. The above is only an outline of China’s remote sensing technology. Compared with the international advanced countries we still have a long way to go in remote sensing. The scientific level of our specialized personnel is not so high. Educational training information service and the processing means of image data are correlatively backward. The applying departments have not mastered advanced interpretation techniques. We should learn from other countries all advanced techniques at the international level. We are very pleased to attend the first Asian Conference on remote sensing in Bangkok. We hold that the exchanges of situation and techniques among the Asian countries will help strenghthen the friendship of all countries in Asian and Pacific region make up each other’s deficiency and raise our scientific level together. We hope that the Asian countries shall enhance mutual cooperation and promote the continuous development of remote sensing in Asia. |