Elevation model (Water Overlay) - Revision history

Maxim@tygron.com at 04:39, 8 July 2026

2026-07-08T04:39:39Z

← Older revision		Revision as of 04:39, 8 July 2026
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	# Calculate a new center point based on the 4 edge center points.		# Calculate a new center point based on the 4 edge center points.

	Given that the adjacent cells share the same corner points, and thus share an edge center point, the bottom will be continuous in the x and y direction. Furthermore, the cell has an linear slope in both the x- and y-direction. ~~The only downside is that~~ the new center point ~~might have been placed heigher~~ or lower in ~~a situation~~ where the terrain's slope was originally ~~not~~ linear within the cell.		Given that the adjacent cells share the same corner points, and thus share an edge center point, the bottom will be continuous in the x and y direction. Furthermore, the cell has an linear slope in both the x- and y-direction. Consequently, the new center point may be higher or lower in situations where the terrain's slope was not originally linear within the cell.
	<gallery widths=400px heights=300px>		<gallery widths=400px heights=300px>
	File:Inundation overlay 04 HWP(2).PNG\|2D linear piecewise reconstruction. Source: Horváth et al. (2014){{ref\|Horvath}}		File:Inundation overlay 04 HWP(2).PNG\|2D linear piecewise reconstruction. Source: Horváth et al. (2014){{ref\|Horvath}}

Frank@tygron.nl at 12:14, 6 July 2026

2026-07-06T12:14:39Z

← Older revision		Revision as of 12:14, 6 July 2026
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	===Piecewise linear reconstruction of the bottom===		===Piecewise linear reconstruction of the bottom===
	The implementation of the Water Module is based on second-order semi-discrete central-upwind scheme by Kurganov and Petrova (2007){{ref\|Kurganov2}}. The [[~~terrain height~~ (Water Overlay)\|surface elevation]], also named bottom in the paper, is slightly adjusted to support the scheme to become ''well balanced and positivity preserving''. The process of adjusting the original surface elevation is called ''piecewise linear reconstruction of the bottom''.		The implementation of the Water Module is based on second-order semi-discrete central-upwind scheme by Kurganov and Petrova (2007){{ref\|Kurganov2}}. The [[Elevation model (Water Overlay)\|surface elevation]], also named bottom in the paper, is slightly adjusted to support the scheme to become ''well balanced and positivity preserving''. The process of adjusting the original surface elevation is called ''piecewise linear reconstruction of the bottom''.
	[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction. Source: Kurganov and Petrova (2007){{ref\|Kurganov2}}]]		[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction. Source: Kurganov and Petrova (2007){{ref\|Kurganov2}}]]
	{{clear}}		{{clear}}
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	\|notes=		\|notes=
	* An [[terrain elevation prequel (Water Overlay)\|alternative elevation model]] can be provided as a [[prequel]].		* An [[terrain elevation prequel (Water Overlay)\|alternative elevation model]] can be provided as a [[prequel]].
	* The smaller the [[grid cell size\|grid size]], the closer the bottom reconstruction will approximate the original [[~~terrain height~~ (Water Overlay)\|surface elevation]].		* The smaller the [[grid cell size\|grid size]], the closer the bottom reconstruction will approximate the original [[Elevation model (Water Overlay)\|surface elevation]].
	* The resulting elevation model can be inspected in a project using the [[Surface elevation result type (Water Overlay)\|SURFACE_ELEVATION]] result type.		* The resulting elevation model can be inspected in a project using the [[Surface elevation result type (Water Overlay)\|SURFACE_ELEVATION]] result type.
	* In case rasterized (roof) heights are important, either:		* In case rasterized (roof) heights are important, either:

Frank@tygron.nl: /* Actions */

2026-05-11T09:56:30Z

Actions

← Older revision		Revision as of 09:56, 11 May 2026
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	** Increase the value configured of the [[Design flood elevation m (Water Overlay)\|design flood elevation model attribute]] for the [[Water Overlay]].		** Increase the value configured of the [[Design flood elevation m (Water Overlay)\|design flood elevation model attribute]] for the [[Water Overlay]].
	** Add a [[Digital Surface Model Overlay]] and configure it for the [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]] of the [[Water Overlay]].		** Add a [[Digital Surface Model Overlay]] and configure it for the [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]] of the [[Water Overlay]].
			* The way in which Bridges are taken into account can be configured using the [[Bridge elevation (Water Overlay)\|Bridge elevation model attribute]].
	\|seealso=		\|seealso=
	* [[Terrain elevation prequel (Water Overlay)]]		* [[Terrain elevation prequel (Water Overlay)]]

Frank@tygron.nl at 09:55, 11 May 2026

2026-05-11T09:55:17Z

← Older revision		Revision as of 09:55, 11 May 2026
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	* [[Levee]]		* [[Levee]]
	* [[Bridge elevation (Water Overlay)]]		* [[Bridge elevation (Water Overlay)]]
			* [[Design flood elevation m (Water Overlay)]]
	\|references=		\|references=
	<references>		<references>

Frank@tygron.nl: /* Actions */

2026-05-11T09:54:33Z

Actions

← Older revision		Revision as of 09:54, 11 May 2026
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	* [[Breach (Water Overlay)]]		* [[Breach (Water Overlay)]]
	* [[Levee]]		* [[Levee]]
			* [[Bridge elevation (Water Overlay)]]
	\|references=		\|references=
	<references>		<references>

Frank@tygron.nl: /* Rasterization of height points of height sectors and buildings */

2026-05-05T11:36:31Z

Rasterization of height points of height sectors and buildings

← Older revision		Revision as of 11:36, 5 May 2026
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	Often the height source has more height values for a particular grid cell. The calculate height value for that grid cell is then calculated as the average of these points.		Often the height source has more height values for a particular grid cell. The calculate height value for that grid cell is then calculated as the average of these points.

	Added to the rasterized land height are the [[building]] ~~heights~~. A building's height is calculated based on the [[Floor height m (Function Value)\|floor height]] times the amount of floors and optional [[Height offset (Function Value)\|height offset]]. In case a building has a [[Custom Geometry]], the height is calculated based on this custom geometry, within the boundaries of the grid cell, with the addition of the optional height offset. The calculated height of a building (including bridges!) is limited by the value configured for the [[Design flood elevation m (Water Overlay)\|design flood elevation model attribute]].		Added to the rasterized land height are the height of [[Solid (Water Overlay)\|solid]] [[building]]s. A building's height is calculated based on the [[Floor height m (Function Value)\|floor height]] times the amount of floors and optional [[Height offset (Function Value)\|height offset]]. In case a building has a [[Custom Geometry]], the height is calculated based on this custom geometry, within the boundaries of the grid cell, with the addition of the optional height offset. The calculated height of a building (including bridges!) is limited by the value configured for the [[Design flood elevation m (Water Overlay)\|design flood elevation model attribute]].

	How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]].		How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]].

Frank@tygron.nl at 11:27, 5 May 2026

2026-05-05T11:27:32Z

← Older revision		Revision as of 11:27, 5 May 2026
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	File:Inundation overlay 04 HWP(1).PNG\|left\|thumb\|400px\|Application of reconstructed elevation Source: Horváth et al. (2014){{ref\|Horvath}}		File:Inundation overlay 04 HWP(1).PNG\|left\|thumb\|400px\|Application of reconstructed elevation Source: Horváth et al. (2014){{ref\|Horvath}}
	</gallery>		</gallery>

			===Actions===
			The following actions influence the rasterized Height Sectors or Buildings, leading to changes in the calculated Elevation model:
			* Planned [[Building]]s and Upgrades
			* Planned [[Levee]]s
			* Planned [[Measure]]s

	{{article end		{{article end

Frank@tygron.nl at 11:25, 5 May 2026

2026-05-05T11:25:49Z

← Older revision		Revision as of 11:25, 5 May 2026
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	* Piecewise linear reconstruction of the bottom		* Piecewise linear reconstruction of the bottom

	==Rasterization of height points of height sectors and buildings==		===Rasterization of height points of height sectors and buildings===
	The base land height values can originate from two sources:		The base land height values can originate from two sources:
	* The [[height sector]]s		* The [[height sector]]s

Frank@tygron.nl: /* Rasterization of height points of height sectors and buildings */

2026-05-05T11:25:42Z

Rasterization of height points of height sectors and buildings

← Older revision		Revision as of 11:25, 5 May 2026
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	* Piecewise linear reconstruction of the bottom		* Piecewise linear reconstruction of the bottom

	===Rasterization of height points of height sectors and buildings===		==Rasterization of height points of height sectors and buildings==
	The base land height values can originate from two sources:		The base land height values can originate from two sources:
	* The height ~~sectors and additional actions (levees~~		* The [[height sector]]s
	* A [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]]		* A [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]]

Frank@tygron.nl at 11:22, 5 May 2026

2026-05-05T11:22:54Z

← Older revision		Revision as of 11:22, 5 May 2026
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	** Add a [[Digital Surface Model Overlay]] and configure it for the [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]] of the [[Water Overlay]].		** Add a [[Digital Surface Model Overlay]] and configure it for the [[Terrain elevation prequel (Water Overlay)\|Terrain elevation prequel]] of the [[Water Overlay]].
	\|seealso=		\|seealso=
	* [[Elevation (Water Overlay)]]
	* [[Terrain elevation prequel (Water Overlay)]]		* [[Terrain elevation prequel (Water Overlay)]]
	* [[~~Design flood elevation m~~ (Water Overlay)]]		* [[Elevation model]]
			* [[Subsidence (Water Overlay)]]
			* [[Surface model (Water Overlay)]]
			* [[Breach (Water Overlay)]]
			* [[Levee]]
	\|references=		\|references=
	<references>		<references>