FAQ Foliage Heat Stress Overlay - Revision history

Frank@tygron.nl at 14:35, 14 July 2026

2026-07-14T14:35:28Z

Frank@tygron.nl at 07:09, 8 July 2026

2026-07-08T07:09:14Z

← Older revision		Revision as of 07:09, 8 July 2026
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	First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[DPRA Heat Stress Module]]. It is not the tree trunks that we are specifically interested in. ~~One of the options to determine foliage~~ height ~~is to use the~~ tree locations, ~~combined with the~~ height ~~of the tree~~ and a crown factor ~~parameter, to determined the foliage height of~~ cells ~~near the tree trunks~~. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].		First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[DPRA Heat Stress Module]]. It is not the tree trunks that we are specifically interested in. Foliage height can be determined using tree locations, tree height, and a crown factor for nearby cells. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].

	Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;		Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;
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	====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====		====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====
	~~Only for~~ foliage option 1 ~~the '~~'Tree'' functions ~~are identified that have~~ a ~~tree~~ crown factor. In order to obtain a foliage height for this ''Tree'' function, the height of this tree is multiplied with the crown factor, which leads to a foliage radius. In case a tree is 10 meters tall and their crown factor is 0.25, their foliage radius is calculated as 10 * 0.25 = 2.5 meters.		For foliage option 1, only 'Tree' functions with a crown factor are used. In order to obtain a foliage height for this ''Tree'' function, the height of this tree is multiplied with the crown factor, which leads to a foliage radius. In case a tree is 10 meters tall and their crown factor is 0.25, their foliage radius is calculated as 10 * 0.25 = 2.5 meters.

	The Heat model will apply a calculation step in which the foliage height will be set based on nearby trees and their foliage radius. The foliage height set will be the height of the tree. There is one exception: if the cell is a building which is taller than the foliage height, there will be no foliage on this cell.		The Heat model will apply a calculation step in which the foliage height will be set based on nearby trees and their foliage radius. The foliage height set will be the height of the tree. There is one exception: if the cell is a building which is taller than the foliage height, there will be no foliage on this cell.
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	====How are trees currently included in the model?====		====How are trees currently included in the model?====
	Trees are used for 2 purposes:		Trees are used for 2 purposes:
	* ~~When~~ foliage option 1 ~~is selected~~, trees ~~are used for determining~~ the foliage height or cells ~~with the tree or surrounding the tree~~. Cells within the crown diameter are given the same foliage height as the cell containing the tree and its foliage height. The foliage height is used for shade and sky view calculations.		* With foliage option 1, trees determine the foliage height for their own cell and surrounding cells. Cells within the crown diameter are given the same foliage height as the cell containing the tree and its foliage height. The foliage height is used for shade and sky view calculations.
	* Trees are ''building-functions'' and therefore have a vegetation fraction and bowen factor. Also cells that are marked having a foliage always receive a vegetation fraction of 1 and a bowen factor of 0.4;		* Trees are ''building-functions'' and therefore have a vegetation fraction and bowen factor. Also cells that are marked having a foliage always receive a vegetation fraction of 1 and a bowen factor of 0.4;

Frank@tygron.nl at 13:35, 13 April 2026

2026-04-13T13:35:33Z

← Older revision		Revision as of 13:35, 13 April 2026
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	First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[Heat ~~DPRA~~ Module]]. It is not the tree trunks that we are specifically interested in. One of the options to determine foliage height is to use the tree locations, combined with the height of the tree and a crown factor parameter, to determined the foliage height of cells near the tree trunks. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].		First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[DPRA Heat Stress Module]]. It is not the tree trunks that we are specifically interested in. One of the options to determine foliage height is to use the tree locations, combined with the height of the tree and a crown factor parameter, to determined the foliage height of cells near the tree trunks. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].

	Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;		Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;

Frank@tygron.nl at 12:12, 13 April 2026

2026-04-13T12:12:37Z

← Older revision		Revision as of 12:12, 13 April 2026
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	====Now that we have a point data set in which each tree is known as a loose point, to which the tree height and crown surface parameters are given at this time. How can I currently see the crown areas, which are calculated in m2, compared to the tree crown factor?'====		====Now that we have a point data set in which each tree is known as a loose point, to which the tree height and crown surface parameters are given at this time. How can I currently see the crown areas, which are calculated in m2, compared to the tree crown factor?'====
	As explained above, the point data set if trees as loose points is not what we look for, we only use the data describing the relative height of the foliage for each grid cell. This foliage height is acquired by any of the three selectable options.		As explained above, the point data set if trees as loose points is not what we look for, we only use the data describing the relative height of the foliage for each grid cell. This foliage height is acquired by any of the three selectable options.
	In order to see the foliage areas, select the result type: Foliage Areas in the Result Overlay step in the Heat Overlay Wizard.		In order to see the foliage areas, select the result type: Foliage Areas in the Result Overlay step in the Heat Stress Overlay Wizard.

	====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====		====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====

Frank@tygron.nl at 11:57, 13 April 2026

2026-04-13T11:57:00Z

← Older revision		Revision as of 11:57, 13 April 2026
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	==FAQ==		==FAQ==
	The following section contains questions and answers.		The following section contains questions and answers.



	====From option 1: How I can adjust functions per tree, and is it possible to include the trees in the analysis, and not to filter them from the data just like buildings.====		====From option 1: How I can adjust functions per tree, and is it possible to include the trees in the analysis, and not to filter them from the data just like buildings.====

Frank@tygron.nl at 11:56, 13 April 2026

2026-04-13T11:56:39Z

← Older revision		Revision as of 11:56, 13 April 2026
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	Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;		Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;
	* ~~Areas~~ with a foliage height parameter.		* [[Area]]s with a foliage height parameter.
	* GeoTIFF with cell specifying the height of foliage per cell, with optional no data when foliage is not present.		* [[GeoTIFF]] with cell specifying the height of foliage per cell, with optional no data when foliage is not present.

	==FAQ==		==FAQ==

Frank@tygron.nl: Frank@tygron.nl moved page FAQ Foliage Heat Overlay to FAQ Foliage Heat Stress Overlay

2026-04-13T11:56:00Z

Frank@tygron.nl moved page FAQ Foliage Heat Overlay to FAQ Foliage Heat Stress Overlay

← Older revision	Revision as of 11:56, 13 April 2026
(No difference)

Frank@tygron.nl at 12:37, 17 January 2022

2022-01-17T12:37:11Z

← Older revision		Revision as of 12:37, 17 January 2022
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	Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;		Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;
	* Areas with a foliage height parameter.		* Areas with a foliage height parameter.
	* ~~Geotiff~~ with cell specifying the height of foliage per cell, with optional no data when foliage is not present.		* GeoTIFF with cell specifying the height of foliage per cell, with optional no data when foliage is not present.

	==FAQ==		==FAQ==
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	====Does the tree then have 1 fixed height value, or does it calculate in the case of a ~~geotiff~~ with several height values to calculate a kind of sphere shape?====		====Does the tree then have 1 fixed height value, or does it calculate in the case of a GeoTIFF with several height values to calculate a kind of sphere shape?====
	Only for option one: Tree functions this question is relevant. The tree has a single height value. If you as a user want more freedom in the definition of the foliage height, you can import the foliage height directly as areas or as ~~geotiff~~ data.		Only for option one: Tree functions this question is relevant. The tree has a single height value. If you as a user want more freedom in the definition of the foliage height, you can import the foliage height directly as areas or as GeoTIFF data.

	====Do you start from a surface file (I see that the few BGT trees are currently defined together as a polygon)?====		====Do you start from a surface file (I see that the few BGT trees are currently defined together as a polygon)?====
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	====I now have a point file for all trees in a test area, with a tree height (m) and a crown area (m2) for each tree. Can I also use the height and crown area from my file in the model? I have tried a few things but it seems that you assume that there is a fixed foliage crown factor for every tree, so that is the same for every tree? I would therefore like to use my own calculated crowns, because a fixed factor is out of the question. Is that possible?====		====I now have a point file for all trees in a test area, with a tree height (m) and a crown area (m2) for each tree. Can I also use the height and crown area from my file in the model? I have tried a few things but it seems that you assume that there is a fixed foliage crown factor for every tree, so that is the same for every tree? I would therefore like to use my own calculated crowns, because a fixed factor is out of the question. Is that possible?====
	Yes, you can use your own crown height when you have this data as areas or ~~geotiff~~ data. The options to these answers are explained above.		Yes, you can use your own crown height when you have this data as areas or GeoTIFF data. The options to these answers are explained above.
	However, one point to mention is that although the ''Input layer'' '''Tree Crown Factor''' can be added, it is not relevant when a user uses areas or ~~geotiffs~~ to specify the foliage heights.		However, one point to mention is that although the ''Input layer'' '''Tree Crown Factor''' can be added, it is not relevant when a user uses areas or GeoTIFFs to specify the foliage heights.

Rudolf@tygron.nl: Rudolf@tygron.nl moved page FAQ Foliage Heat (Overlay) to FAQ Foliage Heat Overlay without leaving a redirect

2019-12-20T15:25:38Z

Rudolf@tygron.nl moved page FAQ Foliage Heat (Overlay) to FAQ Foliage Heat Overlay without leaving a redirect

← Older revision	Revision as of 15:25, 20 December 2019
(No difference)

Frank@tygron.nl at 08:17, 23 September 2019

2019-09-23T08:17:35Z

← Older revision		Revision as of 08:17, 23 September 2019
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	First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[Heat ~~Model~~]]. It is not the tree trunks that we are specifically interested in. One of the options to determine foliage height is to use the tree locations, combined with the height of the tree and a crown factor parameter, to determined the foliage height of cells near the tree trunks. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].		First and foremost, the height of the foliage is required for shade, sky view and vegetation calculations in the [[Heat DPRA Module]]. It is not the tree trunks that we are specifically interested in. One of the options to determine foliage height is to use the tree locations, combined with the height of the tree and a crown factor parameter, to determined the foliage height of cells near the tree trunks. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].

	Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;		Since the foliage of a tree is often not circular and uniform, two additional options allow users to directly supply the foliage height without supplying the tree locations themselves and their crown factors;

← Older revision		Revision as of 14:35, 14 July 2026
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	~~First and foremost, the~~ height ~~of the foliage~~ is required for shade, sky view and vegetation calculations in the [[DPRA Heat Stress Module]]. It is not the tree trunks that we are specifically interested in. Foliage height can be determined using tree locations, tree height, and a crown factor for nearby cells. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].		Foliage height is required for shade, sky view, and vegetation calculations in the [[DPRA Heat Stress Module]]. It is not the tree trunks that we are specifically interested in. Foliage height can be determined using tree locations, tree height, and a crown factor for nearby cells. This leads to circular tree foliage, which is only a rough approximation. For more information on this model, we would also like to refer to [[Foliage_height_calculation_model_(Heat_Overlay)\|Foliage Height Calculation model]].

	~~Since the~~ foliage ~~of a tree~~ is often ~~not~~ circular and uniform, ~~two additional options allow~~ users ~~to directly supply the~~ foliage height ~~without supplying the tree locations themselves and their crown factors;~~		Because tree foliage is often non-circular and non-uniform, users can provide foliage height via:
	* [[Area]]s with a foliage height parameter.		* [[Area]]s with a foliage height parameter.
	* [[GeoTIFF]] with cell specifying the height of foliage per cell, with optional no data when foliage is not present.		* [[GeoTIFF]] with cell specifying the height of foliage per cell, with optional no data when foliage is not present.
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	====For option 3, I would also like to know what this data should look like. For example, is this a grid with height values, where there are only trees? So no individual trees need to be identified?====		====For option 3, I would also like to know what this data should look like. For example, is this a grid with height values, where there are only trees? So no individual trees need to be identified?====
	The grid data provided should present, per cell, the height of the foliage relative to the terrain height. A foliage height of 0 or lower is handled as ''no data'' and ~~therefor~~ ignored.		The grid data provided should present, per cell, the height of the foliage relative to the terrain height. A foliage height of 0 or lower is handled as ''no data'' and therefore ignored.


	====Now that we have a point data set in which each tree is known as a loose point, to which the tree height and crown surface parameters are given at this time. How can I currently see the crown areas, which are calculated in m2, compared to the tree crown factor?'====		====Now that we have a point data set in which each tree is known as a loose point, to which the tree height and crown surface parameters are given at this time. How can I currently see the crown areas, which are calculated in m2, compared to the tree crown factor?'====
	As explained above, ~~the~~ point data set if trees as loose points is not ~~what we look for~~, we ~~only~~ use ~~the~~ data describing the relative height ~~of the foliage~~ for each grid cell. This foliage height is acquired by any of the three selectable options.		As explained above, a point data set of trees as loose points is not used; instead, we use data describing the relative foliage height for each grid cell. This foliage height is acquired by any of the three selectable options.
	In order to see the foliage areas, select the result type: Foliage Areas in the Result Overlay step in the Heat Stress Overlay Wizard.		In order to see the foliage areas, select the result type: Foliage Areas in the Result Overlay step in the Heat Stress Overlay Wizard.

	====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====		====From the sentence "Tree height multiplied by" tree crown factor "judge whether the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?====
	For foliage option 1, only 'Tree' functions with a crown factor are used. In order to obtain a foliage height for this ''Tree'' function, the height of this tree is multiplied with the crown factor, which leads to a foliage radius. ~~In case~~ a tree is 10 meters tall and ~~their~~ crown factor is 0.25, ~~their~~ foliage radius is ~~calculated as~~ 10 * 0.25 = 2.5 meters.		For foliage option 1, only 'Tree' functions with a crown factor are used. In order to obtain a foliage height for this ''Tree'' function, the height of this tree is multiplied with the crown factor, which leads to a foliage radius. For example, if a tree is 10 meters tall and its crown factor is 0.25, the foliage radius is 10 * 0.25 = 2.5 meters.

	The Heat model will apply a calculation step in which the foliage height will be set based on nearby trees and their foliage radius. The foliage height set will be the height of the tree. There is one exception: if the cell is a building which is taller than the foliage height, there will be no foliage on this cell.		The Heat model will apply a calculation step in which the foliage height will be set based on nearby trees and their foliage radius. The foliage height set will be the height of the tree. There is one exception: if the cell is a building which is taller than the foliage height, there will be no foliage on this cell.
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	====What exactly do you mean by foliage? Is that the height of the trees relative to the ground level?====		====What exactly do you mean by foliage? Is that the height of the trees relative to the ground level?====
	Yes, the height of the tree 's foliage relative to the terrain height ~~a.k.a.~~ ground level.		Yes, the height of the tree's foliage relative to the terrain height (ground level).

	====What exactly does the foliage crown factor mean? What is calculated with that? I assume the crown diameter?====		====What exactly does the foliage crown factor mean? What is calculated with that? I assume the crown diameter?====
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	====How are trees currently included in the model?====		====How are trees currently included in the model?====
	Trees are used for 2 purposes:		Trees are used for 2 purposes:
	* With foliage option 1, trees determine the foliage height for their own cell and surrounding cells. Cells within the crown diameter are ~~given~~ the same foliage height as the cell containing the tree ~~and its foliage height~~. The foliage height is used for shade and sky view calculations.		* With foliage option 1, trees determine the foliage height for their own cell and surrounding cells. Cells within the crown diameter are assigned the same foliage height as the cell containing the tree. The foliage height is used for shade and sky view calculations.
	* Trees are ''building-functions'' and therefore have a vegetation fraction and bowen factor. Also cells that are marked having a foliage always receive a vegetation fraction of 1 and a bowen factor of 0.4;		* Trees are ''building-functions'' and therefore have a vegetation fraction and bowen factor. Also cells that are marked having a foliage always receive a vegetation fraction of 1 and a bowen factor of 0.4;