Definition: Mixed objects

Category: Land Use/Land Cover

Three types of mixtures exist on land:

- Spatial mixtures "by juxtaposition" that are highly dependent of scale and observation units. Statisticians apply the prorata rule (case of associated crops and natural biotopes). Many "nomenclatures" attempt to solve the problem by creating mixed classes, resulting in legends since they do not comply with the principle of absence of overlap ); 

- Spatial mixtures in the third dimension are created by "superposition" of different covers or uses. Whatever the resolution of observation, decisions for discriminating the different covers or uses in the third dimension need a rule. A better resolution for observing superpositions does not have any impact: mixtures in the third dimension are therefore scale independent. Statisticians again apply the prorata rule (case of crops associated with tree covered areas). Sometimes specific rules such as dominance are adopted: example of dominant uses for urban.

- Temporal mixtures of covers or uses are highly dependent on the period dt of observation. Agriculture statisticians apply the main crop rule, main being defined through the main commercial value. If this rule is not applicable it is replaced by the crop remaining the longest time on the parcel). http://ec.europa.eu/eurostat/ramon/statmanuals/files/KS-34-00-407-__-I-EN.pdf#page=9