Bề mặt Trái Đất được chia thành các mảng kiến tạo, chúng di chuyển từ từ trên bề mặt Trái Đất trong hàng triệu năm qua. Khoảng 71% bề mặt Trái Đất được bao phủ bởi các đại dương nước mặn, phần còn lại là các lục địa và các đảo; nước là thành phần rất cần thiết cho sự sống, chưa từng phát hiện sự tồn tại của nó trên bề mặt của bất kì hành tinh nào khác. | Geospatial Image Metadata Catalog Services 1. Introduct Ion As earth observation continues worldwide large volumes of remotely sensed data on the Earth s climate and environment have been collected and archived. In order to maintain the data archives efficiently and to facilitate discovery by users of desired data in the holdings each data provider normally maintains a digital metadata catalog. Some online catalogs provide services to users for searching the catalog and discovering the data they need through a well-established Application Programming Interface API . Such services are called Catalog Services. The information in the catalog is the searchable metadata that describe individual data entries in the archives. Currently most Catalog Services are provided through Webbased interfaces. This chapter analyses three open catalog service systems. It reviews the metadata standards catalog service conceptual schemas and protocols and the components of catalog service specifications. 2. rev lew of geosp AtlAL IMAge cAtALog ser vIces Pilot Catalog Service Systems The Federal Geographic Data Committee FGDC Clearinghouse is a virtual collection of digital spatial data distributed over many servers in the United States and abroad. The primary intention of the Clearinghouse is to provide discovery services for digital data allowing users to evaluate its quality through metadata. Most metadata provide information on how to acquire the data in many cases links to the data or an order form are available online. The NASA Earth Observing System ClearingHOuse ECHO is a clearinghouse of spatial and temporal metadata that enables the science community to exchange data and information. ECHO technology can provide metadata discovery services and serve as an order broker for clients and data partners. All the NASA Distributed Active Archive Centers DAACs as data providers generate and ingest metadata information into ECHO. The Open Geospatial Consortium OGC has promoted .
