Elevation model (Water Overlay) - Revision history

Rudolf@tygron.nl at 11:21, 25 February 2026

2026-02-25T11:21:45Z

← Older revision		Revision as of 11:21, 25 February 2026
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	\|link=https://www.tuwien.at/index.php?eID=dumpFile&t=f&f=150915&token=e51c85712b7e70bcb769575d03f4680753d55f01~~, http://visdom.at/media/pdf/publications/Poster.pdf~~		\|link=https://www.tuwien.at/index.php?eID=dumpFile&t=f&f=150915&token=e51c85712b7e70bcb769575d03f4680753d55f01
	\|lastvisit=2026-02-25		\|lastvisit=2026-02-25
	}}		}}

Rudolf@tygron.nl at 10:50, 25 February 2026

2026-02-25T10:50:58Z

← Older revision		Revision as of 10:50, 25 February 2026
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	\|page=		\|page=
	\|source=		\|source=
	\|link=~~http~~://~~www.math~~.tamu.edu/~gpetrova/KPSV.pdf		\|link=https://people.tamu.edu/~gpetrova//KPSV.pdf
	\|lastvisit=~~2018~~-06-29		\|lastvisit=2026-02-25
	}}		}}
	{{ref\|Horvath		{{ref\|Horvath

Rudolf@tygron.nl at 10:48, 25 February 2026

2026-02-25T10:48:25Z

← Older revision		Revision as of 10:48, 25 February 2026
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	\|link=https://www.tuwien.at/index.php?eID=dumpFile&t=f&f=150915&token=e51c85712b7e70bcb769575d03f4680753d55f01, ~~https~~://visdom.at/media/pdf/publications/Poster.pdf		\|link=https://www.tuwien.at/index.php?eID=dumpFile&t=f&f=150915&token=e51c85712b7e70bcb769575d03f4680753d55f01, http://visdom.at/media/pdf/publications/Poster.pdf
	\|lastvisit=2026-02-25		\|lastvisit=2026-02-25
	}}		}}

Rudolf@tygron.nl at 10:48, 25 February 2026

2026-02-25T10:48:12Z

← Older revision		Revision as of 10:48, 25 February 2026
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	\|page=		\|page=
	\|source=		\|source=
	\|link=~~http~~://~~citeseerx~~.~~ist~~.~~psu~~.~~edu/viewdoc/download~~?~~doi~~=~~10.1.1.700.7977~~&~~rep~~=~~rep1~~&~~type~~=~~pdf~~, ~~http~~://visdom.at/media/pdf/publications/Poster.pdf		\|link=https://www.tuwien.at/index.php?eID=dumpFile&t=f&f=150915&token=e51c85712b7e70bcb769575d03f4680753d55f01, https://visdom.at/media/pdf/publications/Poster.pdf
	\|lastvisit=~~2018~~-06-29		\|lastvisit=2026-02-25
	}}		}}
	</references>		</references>

Rudolf@tygron.nl at 14:28, 17 October 2025

2025-10-17T14:28:00Z

← Older revision		Revision as of 14:28, 17 October 2025
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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 ~~name="~~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 [[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''.
	[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction. Source: Kurganov and Petrova (2007)<ref ~~name="~~Kurganov2~~" />~~]]{{clear}}		[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction. Source: Kurganov and Petrova (2007){{ref\|Kurganov2}}]]
			{{clear}}

	The first requirement the scheme to become ''well balanced and positivity preserving'' is to ensure that each grid cell has a constant linear slope in both the x- and y- direction. Secondly the end points of the slope should meet in the center of the cell's edges. This ensures that the bottom is continuous along cells in the x- and y- direction. Thirdly, the linear slope in the x- and y-direction within a cell should meet in a single center point.		The first requirement the scheme to become ''well balanced and positivity preserving'' is to ensure that each grid cell has a constant linear slope in both the x- and y- direction. Secondly the end points of the slope should meet in the center of the cell's edges. This ensures that the bottom is continuous along cells in the x- and y- direction. Thirdly, the linear slope in the x- and y-direction within a cell should meet in a single center point.
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	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. 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.
	<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 ~~name="~~Horvath~~"/>~~		File:Inundation overlay 04 HWP(2).PNG\|2D linear piecewise reconstruction. 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 ~~name="~~Horvath~~"/>~~		File:Inundation overlay 04 HWP(1).PNG\|left\|thumb\|400px\|Application of reconstructed elevation Source: Horváth et al. (2014){{ref\|Horvath}}
	</gallery>		</gallery>

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	\|references=		\|references=
	<references>		<references>
	<ref name=~~"Kurganov2">Kurganov A, Petrova G (2007) ∙~~ A Second-Order Well-Balanced Positivity Preserving Central-Upwind Scheme for the Saint-Venant System ~~∙ found at:~~ http://www.math.tamu.edu/~gpetrova/KPSV.pdf ~~(last visited~~ 2018-06-29~~)</~~ref>		{{ref\|Kurganov2
	~~<ref~~ name=~~"Horvath">~~Zsolt Horváth, Jürgen Waser, Rui A. P. Perdigão, Artem Konev and Günter Blöschl (2014) ~~∙ A two-dimensional numerical scheme of dry/wet fronts for the Saint-Venant system of shallow water equations ∙ found at:~~ http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.700.7977&rep=rep1&type=pdf ∙ http://visdom.at/media/pdf/publications/Poster.pdf ~~∙ (last visited~~ 2018-06-29~~)</ref>~~		\|name=A Second-Order Well-Balanced Positivity Preserving Central-Upwind Scheme for the Saint-Venant System
			\|author=Kurganov A, Petrova G (2007)
			\|page=
			\|source=
			\|link=http://www.math.tamu.edu/~gpetrova/KPSV.pdf
			\|lastvisit=2018-06-29
			}}
			{{ref\|Horvath
			\|name=A two-dimensional numerical scheme of dry/wet fronts for the Saint-Venant system of shallow water equations
			\|author=Zsolt Horváth, Jürgen Waser, Rui A. P. Perdigão, Artem Konev and Günter Blöschl (2014)
			\|page=
			\|source=
			\|link=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.700.7977&rep=rep1&type=pdf, http://visdom.at/media/pdf/publications/Poster.pdf
			\|lastvisit=2018-06-29
			}}
	</references>		</references>
	}}		}}

	{{WaterOverlay formula nav}}		{{WaterOverlay formula nav}}

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

2024-03-05T16:54:05Z

Rasterization of height points of height sectors and buildings

← Older revision		Revision as of 16:54, 5 March 2024
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	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, [[Slanting roof height (Function Value)\|slanting roof height]] 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.		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, [[Slanting roof height (Function Value)\|slanting roof height]] 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.

	These buildings heights are limited by the [[Design flood elevation m (Water Overlay)\|design flood elevation]] and the height taken is whichever is lowest.		How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]].

			These buildings heights (including bridges!) are limited by the [[Design flood elevation m (Water Overlay)\|design flood elevation]] and the height taken is whichever is lowest.

	~~How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]]. More details can be found in that article.~~

	Furthermore certain conditions, such as a configured [[Weir height (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.		Furthermore certain conditions, such as a configured [[Weir height (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.

Frank@tygron.nl at 16:51, 5 March 2024

2024-03-05T16:51:51Z

← Older revision		Revision as of 16:51, 5 March 2024
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	\|seealso=		\|seealso=
	* [[Elevation (Water Overlay)]]		* [[Elevation (Water Overlay)]]
			* [[Terrain elevation prequel (Water Overlay)]]
			* [[Design flood elevation m (Water Overlay)]]
	\|references=		\|references=
	<references>		<references>

Frank@tygron.nl at 16:51, 5 March 2024

2024-03-05T16:51:07Z

← Older revision		Revision as of 16:51, 5 March 2024
Line 20:		Line 20:
	===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 name="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 name="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''.
	[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction.Source: Kurganov and Petrova (2007)<ref name="Kurganov2" />]]{{clear}}		[[File:piecewisereconstruction_1d.png\|left\|thumb\|400px\|1D linear piecewise reconstruction. Source: Kurganov and Petrova (2007)<ref name="Kurganov2" />]]{{clear}}

	The first requirement the scheme to become ''well balanced and positivity preserving'' is to ensure that each grid cell has a constant linear slope in both the x- and y- direction. Secondly the end points of the slope should meet in the center of the cell's edges. This ensures that the bottom is continuous along cells in the x- and y- direction. Thirdly, the linear slope in the x- and y-direction within a cell should meet in a single center point.		The first requirement the scheme to become ''well balanced and positivity preserving'' is to ensure that each grid cell has a constant linear slope in both the x- and y- direction. Secondly the end points of the slope should meet in the center of the cell's edges. This ensures that the bottom is continuous along cells in the x- and y- direction. Thirdly, the linear slope in the x- and y-direction within a cell should meet in a single center point.

Frank@tygron.nl at 16:43, 5 March 2024

2024-03-05T16:43:54Z

← Older revision		Revision as of 16:43, 5 March 2024
Line 1:		Line 1:
	The elevation model is :		The elevation model is determined using two steps:
	* Rasterization of the height sectors		* Rasterization of the height sectors and buildings
	* Piecewise linear reconstruction of the bottom		* Piecewise linear reconstruction of the bottom

	===Rasterization of height points of height sectors===		===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 sectors and additional actions (levees

Frank@tygron.nl at 16:43, 5 March 2024

2024-03-05T16:43:11Z

← Older revision		Revision as of 16:43, 5 March 2024
Line 16:		Line 16:
	How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]]. More details can be found in that article.		How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]]. More details can be found in that article.

	Furthermore certain conditions, such as a configured [[Weir height m (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.		Furthermore certain conditions, such as a configured [[Weir height (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.

	===Piecewise linear reconstruction of the bottom===		===Piecewise linear reconstruction of the bottom===

← Older revision		Revision as of 16:54, 5 March 2024
Line 12:		Line 12:
	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, [[Slanting roof height (Function Value)\|slanting roof height]] 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.		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, [[Slanting roof height (Function Value)\|slanting roof height]] 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.

	These buildings heights are limited by the [[Design flood elevation m (Water Overlay)\|design flood elevation]] and the height taken is whichever is lowest.		How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]].

			These buildings heights (including bridges!) are limited by the [[Design flood elevation m (Water Overlay)\|design flood elevation]] and the height taken is whichever is lowest.

	~~How bridges are handled as buildings depend on the configured [[Bridge elevation (Water Overlay)\|bridge mode]]. More details can be found in that article.~~

	Furthermore certain conditions, such as a configured [[Weir height (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.		Furthermore certain conditions, such as a configured [[Weir height (Water Overlay)\|Weir Height]] or [[Culvert threshold (Water Overlay)\|Culvert Threshold]] can override a grid cell elevation. This overriding also provides a preference for the piecewise linear reconstruction.