CONSTRUCTION OF SMART COMMUNITY BASED ON GIS AND TILT PHOTOGRAMMETRY

As a component of smart city, smart community is the community form in the information age. With people's higher pursuit of living environment, safety, convenience and other intelligent aspects, the construction of smart community continues to accelerate. However, there are still some problems such as uneven community safety management level, data island, insufficient quality service projects and lack of participation of residents. This paper studies and practices the construction of smart community based on GIS and tilt photogrammetry. The smart community uses tilt photogrammetry technology to restore the real scene of the community as the data source. The core work of field data acquisition, 3D model construction and monomer modelling of the real scene is carried out. Then, the smart community web terminal is built based on Cesium.js and Vue.js framework, and the mobile terminal is developed by using WeChat applet. The experiment shows that this system can build a communication bridge between managers and users, and it is convenient for property management personnel to carry out accurate positioning verification, inspection, maintenance and timely feedback of community events on the information reported by users in real time. The whole smart community system can provide intelligent and convenient conditions for residents of the community, It can improve the existing management level of the community and provide the valuable technical reference for the current construction of smart communities.


INTRODUCTION
As a component of smart city, smart community is the community form in the information age. With people's higher pursuit of living environment, safety, convenience and other intelligent aspects, the construction of smart community continues to accelerate. Based on cloud technology, big data and other modern technologies, Smart community is equipped with relevant sensors [1] , and it takes population, legal person, spatial geography, economy and buildings as the basic data resources of smart community platform [2][3][4] . Smart community uses GIS technology, Internet and Internet of things to further improve the level of community public services [5] .
The research on smart communities in China has reached an international level. WU Shengwu proposed to integrate the Internet, medical care, property management, energy and other fields to build a convenient, efficient, environmentally friendly and sustainable smart community development model in 2003 [6] . Starting from the process of community informatization, XIE Hua and GU Ying expounded several major elements of the transformation from the traditional community to the smart community [7] .
The state and local governments have also issued various programmatic documents on the construction of "smart communities". Smart community pilot projects are also underway across the country. For example, Shanghai attaches great importance to the construction of data service platform, focuses on the living needs of residents, and develops smart applications with community characteristics. Haishu wisdom community is committed to the comprehensive integration of regional government administration and public resources to provide efficient services for community residents in Ningbo, Zhejiang province [8] . However, due to the limitation of funds, scientific research and technology and actual residents' needs, the smart community system has the disadvantages of 'looking at the outside but not applying'. Community events cannot be quickly identified and solved in time, and residents' satisfaction with smart communities is insufficient [9] .
Harbin city "Shimao Firenze" residential district is taken as a pilot, this paper explores the establishment of intelligent community based on GIS and tilt photogrammetry, and studies the approach of building a web side of smart community based on Cesium. Js and Vue. Js frameworks. It aims to build a wisdom of integrated residents and management services platform. community residents can enjoy convenient service, which can report by mobile phone, computer landing platform event information, and property managers can receive information on the incident point real-time monitoring and feedback to the community residents event handling process. (1-1) In this formula, the height of photography flight is H; The ground resolution is GSD; The pixel size is a; The focal length of the objective lens is f. In this paper, GSD was selected as 2cm, and the height was selected as 180m according to the experience. 2)The image control points are mainly arranged at the corner points of the region. In practice, the control points will be offset and rearranged due to special situations such as water surface. The real scene 3D model is completed by using the modelling software (ContextCapture). Compared with traditional 3DMax modeling, this method has fast efficiency, high precision and low working intensity [10] .

Model format conversion
Cesiun is an open source Javascript library for map rendering using Web GL. Cesium library supports the 3D tile import of 3D models in GLTF, GLB and dae formats [11] . We need to convert the OSGB format single model file into OBJ format, and then use GLTF conversion tool to make the model into GLTF format.
By importing the monomer model into Cesium, you can conduct web side development by connecting node. The attribute information of the model is stored in MongoDB in the form of text, which is mainly in Grid FS format.

THE DESIGN OF THE INTELLIGENT
COMMUNITY SYSTEM

The overall design
Intelligent community system adopts the Browser/Server structure, by merchants, property management, residents as a major player. With the real 3D model as the underlying data, the system is designed for the participants, the presentation layer, support layer, data layer, network layer, five levels by the web front end development technology and database, and the support layer is the core of the system. The logical structure of the system platform is shown in fig.4. Internet and the Internet of things [12] .
The data layer consists of two parts: 3D model data and attribute data. which is convenient to increase and improve functions over time.

Database design
The intelligent community system adopts MongoDB database. All of Mongo DB's data is stored in the cache, which is much faster to query than a relational database stored on the hard disk [13][14][15] . The model properties file is entered into the database in the canonical form of GridFS file. Each file will store a metadata object in the file collection object, and the large file will be split into several smaller documents through JSON format, it can increase the query speed.

Functional design
The support layer designs corresponding functions according to the needs of users, which are divided into   advice and suggestion window (as shown in fig.8). In order to enhance the accuracy of event reporting, users can obtain the specific spatial information of the event location through the measurement function and report it to the administrator, so that the administrator can accurately locate the event location. It is a meaningful exploration of the theory of smart city construction, and has certain theoretical and practical significance for the construction of smart communities.