Data and Data Management


      Content

      Data management
      Quicklooks of NOAA/AVHRR  images
      The 10 Minutes pan-European Land Use Database

    Data management
     
    1. Introduction
      The development of a consistent methodology to derive a land cover database from remotely sensed information involves a considerable amount of data sets and information. The data consists of satellite as well as ancillary data, collected from numerous sources in various formats. In order to manage and share the data in an efficient manner, an overview of the available data is needed as well as access to the data. Metadata (information about data) will provide the necessary information on the data and an Internet site provides the means to access the data.

      Information on important aspects of the project has been facilitated by the PELCOM homepages. Chapter 9.3 will describe the various components of the PELCOM homepage (Central Project Information Exchange System or CPIES)
       

    1. Metadata

      2. As explained, metadata is used to describe the available project data. For the selection of relevant metadata elements, several initiatives undertaken to arrive at standards in meta information, such as the CEN/TC287 European Standard, the Dutch National Clearinghouse and the standard used by the Federal Geographic Data Committee (FGDC), were compared. From these standards a selection of elements has been made. Table 5.1 lists the elements of the metadata used to describe a geographic dataset.
      This list of elements should however no longer be used as common new so-called metadata cores have been developed. The DUBLIN CORE set of metadata elements has been established as an interdisciplenairy set of metadata elements for electronic discovery. The ESMI project has defined a core set of metadata elements specifically for geographic data based on a common set of metadata elements from the new CEN98 model, the FGDC model and the most recent draft of the ISO metadata standard.

      For the record, the metadata elements selected for the PELCOM project are listed below.
       

      Table 1, elements of metadata
       
      Metadata 
      Description
      Constraint

      M = mandatory

      O = optional
      Dataset identification Identity of this entry (for future update) M
      Dataset title The unique name of the dataset within the owning organisation(s) M
      Alternative title Dataset name as known by Distributor O
      Dataset overview    
      Abstract A brief summary of the content of the dataset  M
      Purpose of production A summary of the intentions with which the dataset was developed M
      Online Linkage The name of an online computer resource that contains the data set. Entries should follow the Uniform Resource Locator (URL) convention of the Internet. O
      Sample An example taken from the dataset being representative for the whole dataset. Reference to a browse graphic URL or a browse graphic caption. O
      Presentation Form The form used to present the data, for example map, model, diagram, remote sensing image O
      Supplemental Information Supplemental O
      Extent    
      Currency of extent data and completeness of dataset    
      Extent date The date of creation of the dataset M
      Extent status The degree to which the dataset meets its proposed final extent. M
      Edition Edition of the dataset M
      Maintenance Inteded dataset maintenance and update frequency O
      Reference    
      Currentness reference The basis on which the time period of content information is determined. For example ground condition or publication date.  
      Planar extent    
      Bounding XY    
      Minlat Minimum latitude decimal degrees M
      Minlon Minimum longitude decimaal degrees M
      Maxlat Maximum latitude decimal degrees M
      Maxlon Maximum longitude decimal degrees M
      Geographic area    
      Name of areal unit Name of the areal unit which is covered in the dataset M
      Id code of areal unit Identifier of the areal unit which is covered in the dataset O
      Temporal extent    
      From date The earliest date to which the dataset corresponds M
      To date The latest date to which the dataset corresponds M
      Data definition    
      Spatial characteristics    
      Geometric primitive types Description of the geometric primitives used in the dataset. Definded as point, vector, raster. M
      Administrative Metadata    
      Distribution Organization    
      Organization name Distributor The name of the organisation that distributes the data M
      Organization address Distributor The postal address, telephone, telefax number, e-mail address of the organisation M
      Point of contact     
      Point of contact name Distributor The name of the person acting as the point of contact M
      Distribution    
      Restrictions on use Constraints regulating the access and usage of the dataset, other than copyright M
      Publisher    
      Organization The name of the organization that published the data O
      Publication Place Place where the data were published O
      Metadata reference    
      Orginator Orginator Metadata entry O
      Last update date Date when the metadata was created or last updated M

       
       

      1. The Interface
      During the project, the possibilities for developing a user interface, which can be addressed from an Internet site, have been investigated. After comparing several options, such as Borland and Access, it was decided to start with the development of a Metadata "Lite" Entry Form. After customisation, this form produces a set of metadata elements whose output meets the minimum data collection requirements for the PELCOM project. The used Metadata "Lite" Entry Form is based on a form developed by the Federal Geographic Data Committee (http://www.fgdc.gov/Clearinghouse/Clearinghouse.html).

      Figure 5 shows the interface for gaining access to the metadata system. A username password combination provides access for each user to the datasets entered by this person. Only the project partners are allowed to enter and change metadata. The user is prompted for a username and password in the first screen. The form offers the possibility to submit a new dataset or to update an existing dataset. In the first screen the user has to pick one of these options. If an existing entry has to be updated the user is asked to select an entry from a list of available entries.

      Figure 5, metadata user access form

      Figure 6 shows the first fields of the actual Metadata "Lite" Entry form. All metadata elements are combined in one single form.

      Figure 6, metadata dataset maintenance/entry form