Research On Large-scene Multi-spectral Image Acquisition Technology

With the development of multimedia information technology and image processing technology,image acquisition systems with high performance,low cost,stable operation,and convenient application are often required in the military field and measurement and control fields.The image acquisition system based on the image acquisition card has the disadvantages of high cost,large size and inappropriate image acquisition in the outdoors.Therefore,this thesis proposes a new solution,which drives the image acquisition device by using the Min Now Board development board,and it controls the image acquisition device by using the remote client to display for image acquisition.This solution has the advantages of small size and low cost,and it is suitable for outdoor acquisition.Large scene multi-spectral image acquisition has three subsystems: image acquisition system,image processing system,and pan-tilt-zoom(PTZ)control system.This thesis mainly studies and implements the image acquisition system.The system is divided into three sub-modules: external device control module,real-time video monitoring module and USB data transmission module.The main works are summarized as follows:1.In the process of outdoor image acquisition,the client needs to remotely control the server to drive the external device to perform image acquisition.Therefore,this thesis designs and develops the external device control module hierarchically.The server side is divided into a device abstraction layer,a device proxy layer,a message distribution layer,a network communication layer,and correspondingly implements an external device abstraction control module,an external device proxy module,a message distribution module,and a network communication module in turn.The client is divided into an interface presentation layer,a data access layer,and a network communication layer,and correspondingly implements a user interface module,a data access module,and a network communication module in turn.The design of modules and hierarchical structures improves the independence and scalability between layer and layer in system.2.Before the image acquisition,it is necessary to observe the capture scene of the camera to determine whether it is a target scene in real time,so a real-time video monitoring module needs to be implemented.In video monitoring module,the functions of video capture,video encoding,video sending,video receiving,video decoding,and video display are realized.The H.264 encoding standard is selected as the video encoding and decoding scheme during the implementation of the video encoding and decoding function.In the process of video sending and receiving functions,a real-time transmission protocol is selected as the video transmission protocol.In the server-side and client-side implementations,multi-threaded control technology is used to improve the efficiency of real-time video capture,transmission,and display.3.For the lack of direct data transmission between the server and the FPGA development board,this thesis designs and implements the USB data transmission module.According to the requirements of this module,the CY7C68013 A interface chip is selected,and the firmware program is designed,and then it is tested by FPGA-based Verilog.Drivers and applications based on Windows platform are implemented on the chip.This thesis finally introduces the testing of the entire image acquisition system.Experiments show that this system is fulfilled the functional requirements and verified the correctness of the system.