View source for ISO 19144-2:2012 Geographic information - Classification systems - Part 2: Land cover meta language

==Overview==
{| class="wikitable"
| Full name
| [http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=44342 ISO 19144-2:2012, Geographic information - Classification systems - Part 2: Land cover meta language]
|-
| Version
| Edition 1
|-
| Amendments
| None
|-
| Corrigenda
| None
|-
| Published by
| ISO/TC 211
|-
| Languages
| English
|-
| Online overview
| https://www.iso.org/obp/ui/#iso:std:iso:19144-2:ed-1:v1:en
|-
| Derived ontologies
| https://github.com/ISO-TC211/GOM/tree/master/isotc211_GOM_harmonizedOntology/19144-2/2012
|-
| Type of standard
| ISO International Standard <br/> Application level
|-
| Application
| For describing different land cover classification systems consistently according to physiognomy, so that they can be compared and data classified according to different land cover classification systems can be combined.
|-
| Conformance classes
| Conformance of a land cover classification system <br/> Conformance of a register for the extension of the metalanguage <br/> Test case for uniqueness of registered metaclass names <br/> Test case for backward compatibility <br/> Conformance of a comparison process of two Land Cover Classification Systems
|-
| Fundamental geospatial dataset
| Category: Environmental information <br/> Data Theme: Natural environment (Land cover)
|}

==Scope==
This part of ISO 19144 specifies a Land Cover Meta Language (LCML) expressed as a UML metamodel that allows different land cover classification systems to be described based on the physiognomic aspects. This part of ISO 19144 also specifies the detailed structure of a register for the extension of LCML but does not specify the maintenance of the register. This International Standard recognizes that there exist a number of land cover classification systems. It provides a common reference structure for the comparison and integration of data for any generic land cover classification system, but does not intend to replace those classification systems.

==Implementation benefits==
There are many different land cover classification systems used around the world, which makes it very difficult to obtain land cover data at a global scale. This is particularly important for assessing environmental changes, such as fluctuations in the biomass in forests. A land cover metalanguage allows one to define the various land cover classification systems on a consistent basis, so that one can combine and compare data in the different classification systems.

[[ISO 19144-1:2009 Geographic information - Classification systems - Part 1: Classification system structure]], specifies the structure for a classification system and the mechanism for defining and registering classifiers, with the result of applying a classification system to an area represented as a discrete coverage (i.e. continuous coverage by non-overlapping polygons). ISO 19144-2:2012 is then an implementation of ISO 19144-1:2009, for land cover. However, it does not specify a directly implementable classification system (or a legend or nomenclature), but rather a metalanguage for describing classification systems for land cover, based on the physiognomic aspects of the land cover. There are obviously other ways for determining land cover, such as the spectral radiation of the land cover.

Once the different land cover classification systems (such as [https://www.eea.europa.eu/publications/COR0-landcover CORINE], Anderson or [http://www.glcn.org/activities/africover_en.jsp Africover]) have been described using LCML (which has already been done for some systems), one can immediately get a better understanding of them and their similarities and differences. This should enable one to combine data from the different land cover classification systems meaningfully – though unfortunately, it might show why it cannot be done. ISO 19144-2:2012 should also help those creating or selecting a new land cover classification system for an application to understand the implications of the options for their classification.

The development of ISO 19144-2:2012 was motivated by the Africover project of the [http://www.fao.org/home/en/ Food and Agriculture Organization] of the United Nations (FAO), which evolved into the FAO’s Land Cover Classification System (LCCS). Hence, the concepts of ISO 19144-2 should be familiar to many experts across Africa who are involved in land cover mapping and analysis.

==Implementation guidelines==
Firstly, ISO 19144-2:2012 should only be used by those with a good understanding of land cover and the principles of classifying on the basis of physiognomy. While Annex C of ISO 19144- 2:2012 does contain extensive examples of types of land cover with illustrations, it is not a tutorial or textbook on land cover classification. The standard uses UML class diagrams extensively (as do most standards from ISO/TC 211), but these should be reasonably easy to understand with a crib sheet on UML conventions.

A class in any land cover classification system can be described by a set of independent elements from LCML, which together form a land cover metalanguage object. In ISO 19144-2:2012, the LCML elements are represented by the class LC_Element and its subtypes. The LCML elements are identified by their appearance or physiognomic aspect and layering or strata. Annex D provides an extensive glossary of land cover meta-elements that may be used to describe the classes in one’s land cover classification system. However, one does not have to use this glossary, which is why the annex is informative and not normative. Clause 9 of ISO 19144-2:2012 explains how to extend the LCML, if required, and how to establish a registry, in conformance with [[ISO 19135:2005 Geographic information - Procedures for item registration]].

LC_Element has two subtypes, LC_VegetationElement (for all surfaces covered by vegetation) and LC_AbioticElement (for all surfaces without vegetation, such as bare soil or artificial structures). The subtypes of LC_VegetationElement are:

:*LC_GrowthForm: woody, herbaceous, lichen and moss, and floating and submerged algae; and
:*LC_GrowthFormCharacteristic: floristic aspect (dominant or most frequent species), allometric measurement (trunk and crown diameters), growth form age, tree area management practices (evenly aged management, clearcutting, seed tree harvesting and unevenly aged management), grazing (intensity and animal type), mowing, vegetation artificiality (natural or semi-natural, vs. cultivated and managed vegetation), and as percentages of vegetation so affected, burnt status, dead status, water stress, vegetation damage (and the type of damage), and growth form illness (and the type of illness).

The subtypes of LC_AbioticElement are:

:*LC_ArtificialSurfaceElement: built-up surfaces (linear, being road, railway and communications and other; and non-linear, being building, other construction and other artificial surface) and non-built-up surfaces (dump site and extraction), and for both, the artificial surface characteristics;
:*LC_NaturalSurfaceElement: rocks (bare rocks and hard pan), and soils and deposits (coarse mineral fragments, bare soil, loose and shifting sand and deposits); and
:*LC_WaterBodyAndAssociatedSurfaceElement: water body (flowing or standing), snow, ice (moving or standing) and permafrost, and for all four, whether above or below surface, the water and associated surface characteristics and periodic variation (atmospheric, daily, tidal and seasonal, duration of persistence, and a description).

As can be expected, ISO 19144-2:2012 caters for more detailed subtypes of these elements and further characteristics of them, but it is beyond the scope of this document to describe them all. Characteristics that can refine all the elements are climate, landform, geographic aspects (beach, bay, estuary and shore), topographical aspects (altitude, slope and aspect), rock type, rock age, soil type, erosion type and sedimentation type. Some of the code lists provided in ISO 19144-2:2012 for the characteristics are empty, but the code lists can be expanded or populated through registration.

What makes LCML very powerful for describing land cover classification systems is that basic LCML elements can be combined into layers or strata in any combination required of vegetated and/or abiotic elements, with the proportions of the elements specified as percentages. Further, there is no limit to the number of strata (ordered, from the surface upwards), which caters for complex three-dimensional land cover classes.

==See also==
* [[ISO 19103:2015 Geographic information - Conceptual schema language]]
* [[ISO 19109:2015 Geographic information - Rules for application schema]]
* [[ISO 19144-1:2009 Geographic information - Classification systems - Part 1: Classification system structure]]
* [[ISO 19135:2005 Geographic information - Procedures for item registration]]