18-23 MSP Multi-Spectral Aerial Photography
Kui Zhongyu,
The Research Institue of Surveying and Mapping
National Bareau of Surveying and Mapping; Beitaipinglu 16,100039
Beijing, China
Niu puning
The General Aviation Co. of Chinay
Abstract
Prior to the research project, the multi-spectral photographic cameras used in the world have a small format (mostly 6cm * 6cm, so it is called 6MSP), the 6 MSP could not be used for mapping; the "harmful absorption" of spectral photometry is great so that the image quality is not up to standard; Due to the small format, the processing work is great during flying and later period. This project uses aerial photo gram metric cameras of format 18cm*18cm and 23*23cm which composed multi-spectral camera groups, and the spectral photometry which has no "harmful absorption" is constituted by "cut-off filter----special sensitive film" that enables the for-mat of the multi-spectral aerial photography to increase by 9 times and 14.7 times more than 6MSP, and it allows" one photography-multiple usage" , e.g. the photographs can be used for mapping and for resources investigation and environment monitoring . As there is no "harmful absorption" so the quality of mult-spectral image is higher, and can be used for visual interpretation and also can be input into computer in order to do the objects classification and interpretation and also can be input into computer in order to do the objects classification and interpretation accurately.18-23 MSP is an efficient aerial remote sensing techniques.
Purpose of the Research
Multi-spectral photography (MSP) had been used in aerial photography in 1959, aimed at carrying out the earth resources investigation. The practice for over twenty years was proved that it is a favorable means for the earth resources investigation, with which many problems of agricultural, forest, water conservancy, geology and environmental projection etc. can be solved. According to the incomplete statistics, there are 29 kinds of MSP photographic cameras in the world, the formats of which are about 6cm*6cm. So they are called 6 MSP photographic systems.
The civil air-photography in China can be divided into two categories: i.e. surveying and mapping; and remote sensing. At present, in the surveying and mapping photography the panchromatic and panchro-infrared photography in mainly used. In the remote sensing the color infrared and multi-spectral photography is mainly used. At the present 6 MSP cameras are used for multi-spectral photography, format is small and camera is no cartographic one; so it is not suitable for mapping. In short, the current two kind of photography are not compatible and the two kinds of photography are required to fly once for each in the same area. Therefore not only
the flying fee is increased by several times, but also the time of data delivery is postponed.
In recent years, the photographic policy of "one photography-multiple usage" was proposed by the National Bureau of Surveying and Mapping and the Civil Aviation Agency of China in accordance with the requirement of national economy reconstruction. "One photography-multiple usage" should break through the policy of "each goes its own way" e.i. The separation between the cartographic photography and the photography for remote sensing. In contrast, it should enable two kinds of photography to be compatible. To this end, the aero-photogrammetric camera must be used to take the multispectral images. This project aims at multi-spectral photography by using the aero-photogram metric camera, format 18cm*18cm and 23c*23cm, so it is called "18-23MSP".
To solve a series problem of the theory, method, equipment and material of 18-23MSP aerial photography is a central content of the subject to be developed. To establish the new aerial photographic method " one photography-multiple usage" which is compatible for mapping and remote sensing is the purpose of 18-23MSP photography.
The brief indication of 18-23MSP technologies
The method of 18-23 MSP aero-photography can be briefly described as following: to carry out simultaneous photography with three aero-photo gram metric cameras of format 18cm*18cm or 23cm*23cm,one spectral band can be recorded by each camera, and to complete spectral photometry " three filter three film method" is applied . Its band ranges are G500~600n m, R600 ~ 700 m n and IR
1 700 ~800 m n respectively, and it can also extend to B400 ~ 500m n and IR2 800~900nm. The interpretation and general analysis can be carried out band by band using the three black and white negatives or photos; otherwise hundreds of multispectral color composites can be obtained by mult-version and multi-spectral composition. All the black and white and color images obtained can be used for the earth resources investigation and environment monitoring. The acquired image can be also input into computer for classification. The original photo or duplicates of band R is applied mapping.
Airplane: An-30
Camera: 3 set AŘA-T3 20 or 3 sets RC-10;
Method of spectral photometry: Three filter three-film method;
Filter: Yellow X C-18, red KC -14, infrared HB-730 and wild C,D,E;
Photo film: (G) 1055, (R) 1065, (IR) and 1075.
Efficient spectral band: 500~600, 600~700, 700~800, can be extended to 400~500 and 800~900(nm)
Format: 18cm*18cm 23cm * 23cm;
Flying height : 4000m ~ 7000m;
Photo scale: 1:20000~1:45000;
Weather requirement: same as the normal photographic requirement;
Lateral and longitudinal overlap: same as the normal photographic requirement, or reduced overlap for resources investigation
Exposure and developing: The contrast coefficient of three films should be consistent as much as
Possible, difference among them
Dr should be not larger than ±0.15;
The print enlargement of B/W film: According to photogram metric requirement using three kinds of negative.
Color composting: According to the requirement of resources investigation, color composition can be carried out by the negatives or positives or egative -positive of three or two films.
