Wind calculation model (Heat Stress Overlay) - Revision history

Maxim@tygron.com: /* Improved wind model */

2026-07-16T13:21:36Z

Improved wind model

← Older revision		Revision as of 13:21, 16 July 2026
Line 149:		Line 149:
	[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]		[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]
	<br clear=all>		<br clear=all>
	Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them. This has been verified by comparison in the Benchmark project showing average 0.05 °C difference ~~(within round off margin)~~.		Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them. This has been verified by comparison in the Benchmark project showing average of only 0.05 °C difference.

	{{article end		{{article end

Maxim@tygron.com: /* Improved wind model */

2026-07-16T13:20:24Z

Improved wind model

← Older revision		Revision as of 13:20, 16 July 2026
Line 149:		Line 149:
	[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]		[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]
	<br clear=all>		<br clear=all>
	Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them. This has been verified by comparison in the Benchmark project showing average 0.05 ~~degrees~~ difference (within round off margin).		Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them. This has been verified by comparison in the Benchmark project showing average 0.05 °C difference (within round off margin).

	{{article end		{{article end

Maxim@tygron.com: /* Improved wind model */

2026-07-16T13:18:15Z

Improved wind model

← Older revision		Revision as of 13:18, 16 July 2026
Line 149:		Line 149:
	[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]		[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]
	<br clear=all>		<br clear=all>
	Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them.		Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them. This has been verified by comparison in the Benchmark project showing average 0.05 degrees difference (within round off margin).

	{{article end		{{article end

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:10:29Z

Improved wind model

← Older revision		Revision as of 12:10, 16 July 2026
Line 141:		Line 141:
	File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons		File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons
	</gallery>		</gallery>
	However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of the report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:		However, the model was not designed for, and cannot always be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of the report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:
	<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>		<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:08:32Z

Improved wind model

← Older revision		Revision as of 12:08, 16 July 2026
Line 141:		Line 141:
	File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons		File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons
	</gallery>		</gallery>
	However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of ~~{{Heat DPRA Report\|~~report}}), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:		However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of the report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:
	<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>		<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:08:16Z

Improved wind model

← Older revision		Revision as of 12:08, 16 July 2026
Line 135:		Line 135:

	==Improved wind model==		==Improved wind model==
	The roughness of the frontal surface influences wind speed, which in turn affects Heat. In the original [[Heat DPRA Report]], the frontal surface is estimated using simplified tree shapes that are aggregated into large woodland/forest [[polygon]]s.		The roughness of the frontal surface influences wind speed, which in turn affects Heat. In the original {{Heat DPRA Report}}, the frontal surface is estimated using simplified tree shapes that are aggregated into large woodland/forest [[polygon]]s.

	<gallery>		<gallery>
Line 141:		Line 141:
	File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons		File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons
	</gallery>		</gallery>
	However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of [[Heat DPRA Report\|report]]), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:		However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of {{Heat DPRA Report\|report}}), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:
	<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>		<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:07:55Z

Improved wind model

← Older revision		Revision as of 12:07, 16 July 2026
Line 135:		Line 135:

	==Improved wind model==		==Improved wind model==
	The roughness of the frontal surface influences wind speed, which in turn affects Heat. In the original {{Heat DPRA Report}}, the frontal surface is estimated using simplified tree shapes that are aggregated into large woodland/forest [[polygon]]s.		The roughness of the frontal surface influences wind speed, which in turn affects Heat. In the original [[Heat DPRA Report]], the frontal surface is estimated using simplified tree shapes that are aggregated into large woodland/forest [[polygon]]s.

	<gallery>		<gallery>
Line 141:		Line 141:
	File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons		File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons
	</gallery>		</gallery>
	However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:		However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of [[Heat DPRA Report\|report]]), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:
	<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>		<math>S_{frontal} = (H_{curr} - H_{prev}) \cdot w_{cell}</math>

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:03:16Z

Improved wind model

← Older revision		Revision as of 12:03, 16 July 2026
Line 139:		Line 139:
	<gallery>		<gallery>
	File:Wind_forest.png\|350px\|thumb\|left\|Trees combined in single forest polygon		File:Wind_forest.png\|350px\|thumb\|left\|Trees combined in single forest polygon
	File:Wind_trees.png\|350px\|thumb\|right\|Same ~~Trees~~ as individual polygons		File:Wind_trees.png\|350px\|thumb\|right\|Same trees as individual spaced polygons
	</gallery>		</gallery>
	However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:		However, the model was not designed for, and cannot be applied to, situations that use very detailed foliage data. For example when using [[Inference Overlay\|AI-detected]] polygons for individual trees the estimated frontal surface can become excessively large (when there is a small single cell gap between tree foliage). Although the original model acknowledges this issue and compensates with a 0.3 surface density λ (see page 95 of report), this can still lead to unrealistic outcomes: wind speed is reduced too much and Heat increases around wooded areas, due to the impact of frontal surface area in the formula:

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:02:29Z

Improved wind model

← Older revision		Revision as of 12:02, 16 July 2026
Line 149:		Line 149:
	[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]		[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]
	<br clear=all>		<br clear=all>
	Note that this value has a minimal impact on large woodland/forest polygons because all trees then become a single ~~polygon~~ without space between them.		Note that this value has a minimal impact on large woodland/forest polygons or connecting tree foliage because all trees then become a single entity without space between them.

	{{article end		{{article end

Maxim@tygron.com: /* Improved wind model */

2026-07-16T12:00:25Z

Improved wind model

← Older revision		Revision as of 12:00, 16 July 2026
Line 146:		Line 146:
	To address this issue, a [[Wind decline angle (Heat Stress Overlay)\|WIND_DECLINE_ANGLE]] of e.g. 45 degrees can be applied to smooth the wind flow, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks with individual tree polygons.		To address this issue, a [[Wind decline angle (Heat Stress Overlay)\|WIND_DECLINE_ANGLE]] of e.g. 45 degrees can be applied to smooth the wind flow, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks with individual tree polygons.

	[[File:Wind_dpra.png\|350px\|thumb\|left\|DPRA: Wind has full impact (<math>S_{frontal}</math>) on next tree even when distance between them is ~~1 meter~~.]]		[[File:Wind_dpra.png\|350px\|thumb\|left\|DPRA: Wind has full impact (<math>S_{frontal}</math>) on next tree even when distance between them is a single cell.]]
	[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]		[[File:Wind_improved.png\|350px\|thumb\|right\|DPRA Improved: Wind impact (<math>S_{frontal}</math>) on next tree is reduced producing more realistic results.]]
	<br clear=all>		<br clear=all>