The "SITRA" : methodological approach (part 2)

The metadata

In a society in continuous evolution, what that actual, the mapping data are assuming more and more a strategic role in the decisional trials related to the management of the territory and to its planning.

The data set present in the data-banks of public administration, or produced by private structures (professionals, society of services, etc.), have a tall economic and informative value, but it’s very difficult use contemporarily them, because are miss the necessary information for their reuse. For understanding such aspect you only have to think about the times that data-set are produced ex-novo only because the existence of the same is not known or because the used formats are not compatible with those standards.

To avoid this problem the agencies proceeded to the definition of clear and repeatable procedures have compiled a proper standard for the territorial metadata.

The metadata, according to the classical definition, can be defined as ’data on the data’ ; they represent the documentation of the data (a kind of certificate) that is destined to furnish useful and immediate information to understand, compare and exchange the data described by them.

The metadata, in the optics of the interoperability (possibility to operate contemporarily and in coordinated way on the same data sets), represent a very useful tool for a rapids management (search, diffusion and acquisition) of the territorial data from authorized subjects.

The writing of the metadatum, if effected contemporary to realization of datum, asks few resources for the appointment because who has created the datum knows perfectly the structure of what he has produced.

The biggest actual problem is represented by missing of metadata for very much of the existing data ; a notable waste of additional resources to rich the historical and structural reconstruction of datum is an immediate consequence of it.

In spite of the obvious simplicity in the realization of the metadatum during creation of data sets, once the generators of data didn’t realize them holding an useless loss of time. Only afterwards they understood the importance of metadata and the necessity to create them for whatever data set (in relationship with the simple spread of the data it is a form to safeguard the developed job too).

From the point of view of the consumer, the importance of the metadata resides in the possibility to know that the datum exists, to appraise its utility for own objectives and, therefore, to decide to purchase it or less.

Within the CARTODATA subproject the utility to realize and to individualize a methodology of job for the metadatum dresses again, perhaps, a greater importance because, treating of experimental procedures in European context, the possibility of interchange of information on the data is more main of the data.

The metadatum, so that does useful, have to contain at least the following information "what thing is there ?", "when did it born ?", "where is located it ?"(geographical location), "Who is the owner of it ?", "As has it done ?" (form of the datum). The existence of these fundamental information allows, once the metadata is public, to search to know, for instance, the territorial data that own region and regarding to the territory of competence.

A metadatum can contain the information that are manifold and are tied up to the detail of the datum to which it refers. For instance with the metadata you can describe, with maximum level of detail, the most the single records of the in partnership database to the cartography or, with minimum detail, you can describe the general cartographic product (for instance the CTR - Technical Regional Map of Molise - see chart 1). The intermediary detail, that we have used in the CARTODATA subproject and that is the most diffused kind, foresees the description of the own elaboration that compose a project (for instance the single sheet of the CTR - you see chart 2).

Within the present job we have followed the standard ISO19115 regarding the criterions of creation of the metadata for the datasets. The choice of this standard, rather than of that American FGDC, has been determined by the consideration that the greatest part of the Italian and European local authorities are reporting to it.

The information that we have used for the creation of the metadatum represent the Core Metadata or the necessary least data.

The informations that are in the metadata can be divided according to the following groupings :

1. Information on the whole metadata
2. Information of identification of the data
3. Information on the ties of the data
4. Information on the spatial representation
5. Information on the management
6. Information on the quality of the data
7. Information on the system of reference
8. Information on the distribution
9. Information on the extension of the data
10. Information of responsibility

The first two groups contain the information related to the identification of the metadatum (who has created him ? when ? what standard with ?) and to the data type in partnership with it. The information on the ties contains the limitations for using for legal reasons or for intrinsic reasons for the datum (for instance an elaborate product in scale 1:250.000 won’t be fit for elaborations in scale of detail). The information on the spatial representation have to be compiled only for images and DTM. For system of reference we intend the name of the system of reference (eventually also the parameters of the Datum, etc.). The information on the quality of dataset is very important for describing the process of realization of the datum and its accuracy. The refresh rate of the datum is described in the group information on the management. If an organization proceed to the distribution of the datum exists, it has to point out in the information on the distribution. Through the indication of the maximum and least coordinates the information of extension can be individualized. That concerns the responsibilities of the datum and the metadatum associated it has be pointed out finally, in the section of the information on the responsibility.

In the table that follows, you can see a chart of dataset presents in the metadatum set within the CARTODATA subproject, according to the standard ISO19115. In bold are written the compulsory while in cursive are written the optional fields ; in normal characters are written the conditional fields or those necessary for some types of datum.

Information on the whole the metadata
1	Identifier of the file of metadata
2	Language of the metadata
3	Set of the characters of the metadata
4	Identifier metadata of superior rank
5	Hierarchical level
6	Contact	Name of the corporate body
		Role
		Information to contact the corporate body	Site web
			Telephone
7	Date of the metadata
8	Name of the Standard of the metadata
9	Version of the Standard of the metadata
10	Limitation of use of the metadata
	Ties of access of the metadata
	Ties of user of the metadata
	Other ties on the metadata
Information of identification of the data
11	Title
	Date	Date
		Type dates
	Responsible of the data	Name of the corporate body
		Role
		Information to contact the corporate body	Site web
			Telephone
	Data type
	Other details
12	Description
13	Key words	Key word
		Thesaurus
14	Point of contact	Name of the corporate body
		Role
		Information to contact the corporate body	Site web
			Telephone
15	Type of spatial representation
16	Spatial resolution of the data	It climbs equivalent
		Distance
17	Language of the data
18	Set of characters of the data
19	Theme
20	Geographical location of the data	westBoundLongitude
		eastBoundLongitude
		southBoundLatitude
		northBoundLatitude
	Vertical extension	It rates min
		It rates max
		Unity of measure
		Vertical Datum
21	Additional information
22	Graphic example
Information on the ties of the data
23	Limitation of use of the data
24	Ties of access of the data
25	Ties of fruibilità of the data
26	Other ties on the data
Information on the quality of the data
27	Level of quality
28	Quality of the data (positional accuracy)	Unity of measure
		Value
Information on the origin and on the process of production of the data
29	Genealogy of the datum Process of production
Information on the system of reference
30	System of spatial reference
Information on the distribution
31	Formed of distribution	Formed name
		Version formed
32	Distributor	Name of the corporate body
		Role
		Information to contact the corporate body	Site web
			Telephone

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