|地物 : 土地表面|
現在、 landcover のタグ付けはふつう他のタグに含まれています。例えば、公園は草でおおわれていると想定されます。しかし、場所によっては木や砂や他のものに覆われていることもあります。以下のキーは landcover 属性を暗黙に仮定したり定義したりします。
- landuse=* - many types of Landuse imply a certain type of landcover (like landuse=meadow) but some do not (like landuse=military) and others can be ambiguous in this regard, like in case of landuse=greenfield, which can imply any type of vegetation or bare ground. Same applies for other keys indicating Landuse like amenity=*, leisure=* and tourism=*.
- surface=* - which specifies the surface material and properties in a similar way as landcover but this tag was originally created to describe the surface of linear features within a routable network and as such had values which are relevant to this purpose rather than broader landcover descriptions. It is meanwhile also used to indicate the surface type of larger areas, like for a Landuse but is generally used as a secondary tag.
- natural=* - many tags of this key meant for tagging areas refer to Natural features with a clearly implied landcover. Some tags are however not very specific regarding landcover like natural=beach or natural=fell and require additional tags like surface=* to clarify the landcover.
- landcover=* - this has been proposed in Proposed features/landcover to directly tag landcover types.
One of the most difficult cases for landcover mapping is woodland/forests. See JA:森林 for more details. There is not currently a good tag to describe a landcover of trees as opposed to a landuse of timber production for which landuse=forest is appropriate or natural=wood for primary unmanaged woodland. The tag landcover=trees has been proposed for this purpose. In addition, landuse and landcover are often confused. For example landuse=grass actually describes a landcover, not a use. This causes problems as one can not describe an area of railway land as being primarily covered with grass as the landuse tag is used for both purposes.
以下の表はかなり不完全です。追加をお願いします。 The following list is very incomplete. Please add to to. The table is sortable by clicking on the relevant column heading:
|泥炭地（湿原）||Natural||natural=wetland and wetland=bog|
|草原||Natural||Currently landcover is implied by the use of landuse=grass, leisure=park, surface=grass, landuse=meadow, natural=grassland, etc. It is typical that landuse=grass is misused and should be changed to landcover=grass (for example: patches of grass between tracks in railway corridor - area that should be tagged with landuse=railway).|
|Marsh||Natural||natural=wetland and wetland=marsh|
|マングローブ||Natural||natural=wetland and wetland=mangrove|
|Reedbed||Natural||natural=wetland and wetland=reedbed|
|Saltmarsh||Natural||natural=wetland and wetland=saltmarsh|
|海||Natural||The natural=coastline tag is used to define the boundary between land and the sea (at the high water mark). The boundary between the land and the sea is rich in different landuses, see 'gravel', 'mangrove', 'saltmarsh', 'sand', 'swamp' and 'tidal flat'.|
|Swamp||Natural||natural=wetland and wetland=swamp|
|Tidal flat||Natural||natural=wetland and wetland=tidalflat|
|Trees||Natural||Currently the landuse=forest or natural=wood are used but neither of these work well for planted and managed trees in a park for example.|
|水辺||Natural||waterway=riverbank,natural=water,man_made=reservoir. See also: 'sea'.|
Systems of Landcover classification
The landcover classification systems mentioned in the following are all based on the notion that all land surface can be classified into a limited set of landcover classes, either a fixed a priori classification or a dynamic set of a certain number of classes. Since OpenStreetMap uses a globally uniform but open tagging system - see 何でも好きなタグを - neither of these can be directly translated into OSM tag combinations.
A priori and a posteriori systems
In an a priori classification system the classes are abstractions of the types actually occurring. The approach is based upon definition of classes before any data collection actually takes place. This means that all possible combinations of diagnostic criteria must be dealt with beforehand in the classification. The main advantage is that classes are standardized independent of the area and the means used. The disadvantage, however, is that this method is rigid, as some of the field samples may not be easily assignable to one of the pre-defined classes.
A posteriori classification differs fundamentally by its direct approach and its freedom from preconceived notions. The approach is based upon definition of classes after clustering similarity or dissimilarity of the field samples collected. The advantage of this type of classification is its flexibility and adaptability compared to the implicit rigidity of the a priori classification. The a posteriori approach implies a minimum of generalization. This type of classification better fits the collected field observations in a specific area. At the same time, however, because an a posteriori classification depends on the specific area described and is adapted to local conditions, it is unable to define standardized classes. Clustering of samples to define the classes can only be done after data collection, and the relevance of certain criteria in a certain area may be limited when used elsewhere or in ecologically quite different regions.
NLCD92 - National Land Cover Database
National Land Cover Database (NLCD) is a land cover classification scheme that has been applied consistently across all 50 United States and Puerto Rico. NLCD is based primarily on Landsat satellite data.
|Water|| 11 Open Water
12 Perennial Ice/Snow
|Developed|| 21 Low Intensity Residential
22 High Intensity Residential
|Barren Land|| 31 Bare Rock/Sand/Clay
32 Quarries/Strip Mines/Gravel Pits
|Forested Upland|| 41 Deciduous Forest
42 Evergreen Forest
43 Mixed Forest
|Non-Natural Woody||61 Orchards/Vineyards/Other|
|Herbaceous Upland Natural/Semi-natural Vegetation||71 Grasslands/Herbaceous|
|Herbaceous Planted/Cultivated|| 81 Pasture/Hay
82 Row Crops
83 Small Grains
85 Urban/Recreational grasses
|Wetlands|| 91 Woody Wetlands
92 Emergent Herbaceous Wetlands
|See USGS landcover classes.|
LCCS - Land Cover Classification System
The Land Cover Classification System (LCCS) is the result of an initiative to take a first step towards an internationally agreed reference base for land cover. The objectives of the Africover Programme of the Environment and Natural Resources Service (SDRN), FAO, are to develop an approach for conceptualizing, defining and classifying land cover.
Definition: Land cover is the observed (bio)physical cover on the earth's surface.
One of the basic principles adopted in the new approach is that a given land cover class is defined by the combination of a set of independent diagnostic attributes, the so-called classifiers. There are 83 main classifiers (Type A), 13 Type B, 19 Type C, 3 Type D, 7 Type E, 10 Type F, 2 Type G (numbers are not approved).
The creation of the land cover class is given by the combination of a set of pre-defined pure land cover classifiers. This set of classifiers is different for each of the eight main land cover types. E.g. trees can have classifier A1 or A3; shrubs can have A2 or A4; B1 stands for large to medium sized fields or height 7-2m or Dunes.
The main criteria is the uppermost canopy layer. This means that the dominant layer goes from Tree canopy to Shrub to Herbaceous/Forbs/Graminoids.
The user can describe up to three layers of stratification (including the main layer) for Terrestrial Vegetation (A12) and up to two layers in Aquatic or Regularly Flooded Vegetation (A24). "Tree Savannah" is clearly defined by two main elements: a Herbaceous vegetation layer and a Sparse Trees layer. Thus, the Stratification of the two elements Herbaceous and Tree layer is crucial for the definition of this class. "Closed Forest" is clearly defined by the element of a Closed Trees layer. Limitations have been introduced for this class in the use of Stratification. All limitations in use of Stratification are built into the software application.
It is crucial where the classifier (e.g. trees) appears, in the main layer or second or third layer.
Examples for results of LCCS-Code in main type A12. Natural and Semi-Natural Vegetation:
- A3.A10 - Closed forest
- A3.A10.B2.C1.D1.E2 - Broadleaved dedicious forest
- A3.A10.B2.C1.D1.E2.F2.F5.F7.G2 - Multi-layered broadleaved dedicious forest
- this combinations have a completely different meaning in other main types
|Main types||Classifier||Classifier||Classifier||Picture||Some possible results after classification|
|A11. Cultivated and Managed Terrestrial Areas||A1. Trees||A7. Broadleaved||Leaf Phenology|| Tree Crops|
|A8. Needleleaved||Leaf Phenology|
|A2. Shrubs||A7. Broadleaved||Leaf Phenology|
|A8. Needleleaved||Leaf Phenology|
|A3. Herbaceous||A4. Graminoids|
|A5. Non Graminoids|
|A6. Urban vegetated areas||A11. Parks|
|A12. Natural and Semi-Natural Vegetation||A1. Woody||A3. Trees|| Cover
|A4. Shrubs|| Cover
|A2. Herbaceous||A5. Forbs|
|A7. Lichens/Mosses||A8. Lichens|
|A23. Cultivated aquatic or regulary flooded areas||A1. Graminoids|| Aquatic Or Regularly Flooded Graminoid Crops|
Aquatic Or Regularly Flooded Non-Graminoid Crops
|A2. Non graminoids|
|A24. Natural and Semi-Natural Aquatic or Regularly Flooded Vegetation||A1. Woody||A3. Trees|| Forest|
|A2. Herbaceous||A5. Forbs|
|A7. Lichens/Mosses||A10. Lichens|
|B15. Artificial Surfaces and Associated Areas:||A1. Built-up||A3. Linear||A7. Roads|| Built-Up Areas|
Non Built-Up Areas
|A4. Non Linear||A12. Industrial Areas|
|A11. Urban Areas|
|A2. Non built-up||A5. Waste dump deposits|
|A6. Extraction sites|
|B16. Bare Areas||A1. Consolidated||A3. Bare Rock a/o Coarse Fragments||A7. Bare Rock|| Consolidated Areas|
|A4. Hardpans|| A9 Ironpan
|A2. Unconsolidated||A5. Bare Soil||Not stony|
|A13. Very stony|
|A6. Loose and shifting sand||Not stony|
|A13. Very stony|
|B27. Artificial Waterbodies, Snow and Ice:||A1. Artificial Waterbodies||A4. Flowing|| Artificial Waterbodies|
|A2. Artificial Snow|
|A3. Artificial Ice|
|B28. Natural Waterbodies, Snow and Ice:||A1. Natural Waterbodies||A4. Flowing|| Natural Waterbodies|
|A2. Natural Snow|
|A3. Natural Ice|
|See Land Cover Classification System (LCCS).|