LCZ classification

WARNING: The article describing the full method of the LCZ attribution is currently under writing. You will soon find more informations on the References page.

GeoClimate computes the Local Climate Zones (LCZ) at the RSU's scale.

The LCZ, introduced by Stewart & Oke (2012, 2014), is a classification scheme used to segment the climate area's of cities( and other).

Methodology

A LCZ type is assigned to a RSU. This "assignment" is performed according to the 7 indicators used for LCZ classification (sky_view_factor, aspect_ratio, building_surface_fraction, impervious_surface_fraction, pervious_surface_fraction, height_of_roughness_elements and terrain_roughness_class). Each LCZ type has a given range for each of the 7 indicators. Then the method to find the LCZ type that is the most appropriate for a given RSU is based on the minimum distance (MIN_DISTANCE) to each LCZ (in the 7 dimensions space). In order to calculate this distance, each dimension is normalized according to the mean and the standard deviation (or median and absolute median deviation) of the interval values. Some of the indicators may be more important (or reliable) than the other for the LCZ identification. In order to manage this point, a map containing weights may be passed and will be used to multiply the distance due to a given indicator.

The distance of each RSU to each of the LCZ types is calculated in the normalized interval. The two LCZ types being the closest to the RSU indicators (LCZ_PRIMARY and LCZ_SECONDARY) are associated to this RSU. Three indicators are also used to show the degree of certainty of the allocated LCZ class:

• MIN_DISTANCE: it is the distance from a RSU point to the closest LCZ type (the lower the more certain the LCZ_PRIMARY value)
• LCZ_UNIQUENESS_VALUE: indicates how sure is the LCZ type attributed as primary value (the closest from 1 the more certain the LCZ_PRIMARY value)
• LCZ_EQUALITY_VALUE: indicates whether the LCZ type of a RSU could be any LCZ type (the closest from 0 the more certain the LCZ_PRIMARY value).

Note that this method is only valid for most of the built LCZ types. For LCZ types 8, 10 and all land-cover LCZ types, the method is slightly different and will be further described in the article available soon in the References page (the LCZ classification source code is available here for those who can not wait). For LCZ types 8, 10 and all land-cover LCZ types, LCZ_SECONDARY, MIN_DISTANCE, LCZ_UNIQUENESS_VALUE, LCZ_EQUALITY_VALUE are set to null.

Output LCZ layer

Field name	Field type	Definition
ID_RSU	integer	RSU's unique id
LCZ_PRIMARY	integer	Main LCZ type
LCZ_SECONDARY	integer	Secondary LCZ type
MIN_DISTANCE	double precision	Minimum distance to each LCZ
LCZ_UNIQUENESS_VALUE	double precision	Indicates how unique is the attributed LCZ type. Only valid for LCZ1 to LCZ7 and LCZ9. LCZ_UNIQUENESS_VALUE = (DISTANCE LCZ_PRIMARY - DISTANCE LCZ_SECONDARY) / (DISTANCE LCZ_PRIMARY - DISTANCE LCZ_SECONDARY)
LCZ_EQUALITY_VALUE	double precision	indicates whether the LCZ type of a RSU could be any LCZ type

LCZ_PRIMARY and LCZ_SECONDARY column values

Each LCZ value is encoded using the following Type code.

For each of them, we give the LCZ class name and an hexadecimal color code to build map (default .sld file format can be downloaded at this adress).

Type	Type definition	Hexa Color code
1	LCZ 1: Compact high-rise	#8b0101
2	LCZ 2: Compact mid-rise	#cc0200
3	LCZ 3: Compact low-rise	#fc0001
4	LCZ 4: Open high-rise	#be4c03
5	LCZ 5: Open mid-rise	#ff6602
6	LCZ 6: Open low-rise	#ff9856
7	LCZ 7: Lightweight low-rise	#fbed08
8	LCZ 8: Large low-rise	#bcbcba
9	LCZ 9: Sparsely built	#ffcca7
10	LCZ 10: Heavy industry	#57555a
101	LCZ A: Dense trees	#006700
102	LCZ B: Scattered trees	#05aa05
103	LCZ C: Bush,scrub	#648423
104	LCZ D: Low plants	#bbdb7a
105	LCZ E: Bare rock or paved	#010101
106	LCZ F: Bare soil or sand	#fdf6ae
107	LCZ G: Water	#6d67fd