Big data is a data group with a huge amount of data that cannot be easily captured, managed and processed in a certain time. The paper concerns the development of big data in food industry, introduces overview of big data, discusses three big data mining technologies, and outlines its potential value in food management.
To precisely calculate geometric parameters of space-borne optical imaging systems, such as object distance, projection angle, ground sampling distance(GSD), swath width, the effect of earth curvature and projection angle is researched,as nadir imaging and roll imaging. In this paper, a precise geometric model is proposed, which is based on earth curvature and projection angle. Two types of space-borne optical imaging systems are simulated by the model. They are single camera and combined camera with large field of view (FOV). They are on 644.5km orbit, with full field of view 64.44°。The analysis shows that, the GSD of combined camera changes rapidly with field angle, the maximum GSD is 2.07 times of the minimum GSD. The GSD of single camera changes less rapidly with field angle, the maximum GSD is 1.75 times of the minimum GSD. The swath widths of sub-cameras of combined camera are different. The two marginal sub-cameras have larger swath width than the two central ones. The precise calculation of geometric parameters is significative to ensure the imaging quality.
The urgent need for the precise, real-time position metrology between the optical components in a modern space camera is becoming more critical with the increased resolution, aperture, focal length, and light-weighted structure. Gravity offload, composite material humidity desorption, temperature cyclical variation with the illumination, and micro-vibration on platform would introduce unpredictable affect to decrease the imaging quality. The solution of the optical system disorders would mainly rely on the ground-based stimulation and on that basis, active optics compensation, which could not be accurate. This influence expands within the opto-mechanical structure complexity. This paper represents an implement solution for position and attitude metrology used for on-orbit real-time measurement. To deal with the contradiction of system accuracy and simplicity, we simplified the system to a measurement model equivalent to 6 degree of freedom Stewart Platform structure. The works on this paper tightly coupled to the accuracy requirement of a long focal length optical system. After carefully compare the systematic requirement and balance the implementation costs, we applied the common-path, multi-channel heterodyne interferometers to accomplish the large-scaled coarse measurement for the step disturbance and small-range fine measurement to sense the ambient vibration. The metrology accuracy analysis and error evaluation indicated an effectiveness of this metrology system, which met the requirement of our given optical system. It was indicated in this paper that the metrology method could be generalized in other optical systems and similar long focal length optical systems in the future.
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