Feature attributes (Heat Overlay)

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.

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Heat Module

Heat Module

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Feature attributes

Building attributes

Bowen ratio • Foliage crown factor • Vegetation fraction

Terrain attributes

Vegetation fraction

Area attributes

Foliage height

Related

Calculation models and formulas • Feature attributes • Model attributes • Result types