Feature attributes (Heat Overlay)

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Several geopgraphical features can have attributes which can contribute to the calculations the Heat Overlay. These attributes are stored as part of the features, and are then rasterized and used on a grid cell level.

Building attributes

Building attributes can be changed individually per Building or per Building's function. In most cases, these attributes already exist as a function value.

Icon Attribute Unit Function value Description
BOWEN_RATIO ratio Bowen ratio Describes the rate of heat transfer for a surface that has moisture as a factor.
FOLIAGE_CROWN_FACTOR ratio Foliage crown factor The ratio between the height of tree trunks and the radius of the foliage of the tree.
VEGETATION_FRACTION fraction Vegetation fraction The amount of the surface which is considered vegetation.

Terrain attributes

Terrains define standard vegitation features. If for any location no Building is present with the appropriate attributes, the attributes of the underlying terrain are used instead.

Attribute Unit Terrain type Description
VEGETATION_FRACTION fraction Surface The amount of the surface which is considered vegetation.

Area attributes

Areas may define additional or overwriting data, where better data than that extrapolated from buildings or terrains is available.

Attribute Unit Description
FOLIAGE_HEIGHT m The top height of foliage for a surface geometry described by an Area.