Design And Algorithm Optimization Of Visibility WebGIS System On Highway

With the rapid development of society and economy,the scale of highway construction is also gradually expanding.At present,the total mileage of expressways has reached 104 thousand kilometers,ranking first in the world.Although the expressway has solved the traffic problems,it is very easy to be affected by the weather.Therefore,the design of the highway visibility system is essential for people's safe travel.At present,many factors restrict the construction of the visibility system.Firstly,the traditional visiometer is too expensive and its range of application is limited,so it is hard to set up.Secondly,the existing video detection algorithms require too much external conditions,which are vulnerable to noise and can not guarantee the accuracy of detection.Thirdly,most of the traditional visibility display systems based on WebGIS use HTML as the information carrier,and don't have great interactivity.The design of display system is built with three layers of architecture,,which lead to service call protocol is relatively large and the development difficulty is increased.Moreover,most of the GIS applications continue to transition from the C/S architecture to the B/S architecture,The user sends a request to the server through the client,and which is returned to the client after processing of the server.All information processing is dependent on the server,which will cause the server burden,and eventually lead to collapse.In order to guarantee the detection accuracy of freeway visibility,a video visibility detection algorithm based on camera self calibration is proposed.At present,most of the highway installation monitoring cameras can realize video network transmission.In the visibility detection model,firstly,the camera's self calibration technique is used to recover the information of the image,and set up the virtual observation object;secondly,the edge of object is extracted by wavelet transform to remove noise;thirdly,the target is detected by the normalized contrast method,and the contrast information will be extracted;finally,by curve fitting we can obtain the visibility curve that shows visibility distance.Then we compare the visibility distance with normal sight distance to obtain the visibility of camera monitoring section.In order to solve some disadvantages of traditional WebGIS system,it is necessary to design the architecture of the system again.First of all,the current popular Internet rich RIA technology provides a lot of user experience,and solve the cross platform,browser and other issues.Secondly,a lightweight REST call protocol is adopted.Thirdly,the ArcGIS Server is uesd as the publishing server of map data to make the best of advantage of the server architecture.Finally,the technology of map caching need to be improved.Visibility detection algorithm and WebGIS system solve the problems existing in the traditional visibility detection system,and make the accuracy and function of visibility detection system more perfect.At the same time,this system will provide good suggestions for the safety of the people travel.Then,the problem of frequent occurrence of traffic accidents,which result from low visibility and obstruction of sight distance is avoided.