Hello Hao, and welcome back! Le 09/03/2018 à 03:44, phuong hao nguyen thi a écrit :
> Each time the system operates the system will have to repeat the reading of > different image formats and mapping to ISO19115 , it is very time consuming . > So Can I convert image sattelite (Landsat 7,8,9 ,modis... ) to a general > data format for storage (ex: netCDF) without loss of data ? We could convert the metadata information from Landsat format to netCDF-CF, but I would not expect a lot of performance improvement. Furthermore there would be lost of data, unless we define non-standard netCDF attributes in addition to the one defined by the CF convention. A more scalable solution is to use a database. We read Landsat, MODIS or netCDF files only once and store relevant metadata in a PostgreSQL or Derby database. This database would be used by the CSW engine for performing the search. The definition of a database schemas for ISO 19115 metadata is part of the work that need to be done in the proposed Google Summer of Code project. Note that SIS already has a package doing part of the work: http://sis.apache.org/apidocs/org/apache/sis/metadata/sql/package-summary.html This package applies a one-to-one relationship between ISO 19115 class names and database tables. For example it creates a CI_Citation table for the CI_Citation object defined by ISO. Those tables are created and expanded dynamically when new data are inserted. However this mechanism has limitations. How to resolve them is an open question. Martin
