Research On The Key Technologies Of Building Digital Orthophoto Map Database

Digital Orthophoto Map (DOM) is a product of fundamental geographic information, which has geometric features and imaging characteristics. It plays an important role in the social economic development. With the increase of DOM data, it is important to build the DOM database to integrate data storage and to manage data safely. The establishment of the DOM database is significant for the construction of digital city.In the process of building DOM database, there are two key technical problems. The first is to establish the spatial index to improve the efficiency of data query and management. The second is to establish the mechanism of data updating and historical retrospect in order to use the DOM data maximum. This paper is concerned with these problems. The main contents are as follows:(1) After analyzing the characteristics of DOM data, this paper proposes a management model of the DOM database based on the current situation of actual data and its management.(2) With the DOM database management model, the paper studies the method of building the multi-level spatial index of images data. And with this method the user can query data efficiently.(3) A temporal DOM database is designed, based on the relational spatio-temporal data model. Also, an effective management method is introduced for the current and historical data by using this database.(4) With the temporal characteristics of three spatio-temporal databases, the mechanism of DOM data updating is established based on the metadata management. With this mechanism, the DOM data and its metadata can be updated simultaneously. The paper also introduces the method of historic data query. In this method, the historical retrospect is implemented by the spatial and temporal conditions.