How to use buffers (TQL) - Revision history

Frank@tygron.nl at 16:21, 30 January 2024

2024-01-30T16:21:10Z

← Older revision		Revision as of 16:21, 30 January 2024
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	<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>		<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>

	~~==Notes=~~=		{{article end
			\|notes=
	When using buffers, take the following into consideration:		When using buffers, take the following into consideration:
	* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Buildings\|buildings]].		* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Buildings\|buildings]].
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	* When using a BUFFER clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a BUFFER clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.
	* By using the [[TQL#Building polygons\|LOTPOLYGONS]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.		* By using the [[TQL#Building polygons\|LOTPOLYGONS]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.
			\|seealso=
			* [[Buffer (TQL Param)]]
			* [[TQL]]
			}}

			[[Category:How-to's]]

Frank@tygron.nl at 10:31, 28 February 2023

2023-02-28T10:31:56Z

← Older revision		Revision as of 10:31, 28 February 2023
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	__NOTOC__		__NOTOC__
	With the [[TQL~~#Transformations\|BUFFER~~]] clause of [[TQL]], it is possible to retrieve data not just within a specified contour, but in the vicinity of this contour (specified with a distance) as well.		With the [[Buffer (TQL Param)]] clause of [[TQL]], it is possible to retrieve data not just within a specified contour, but in the vicinity of this contour (specified with a distance) as well.

	==How buffers are applied==		==How buffers are applied==

Maxim@tygron.com at 15:21, 7 October 2022

2022-10-07T15:21:49Z

Rudolf@tygron.nl: /* Notes */

2019-11-06T15:46:14Z

Notes

← Older revision		Revision as of 15:46, 6 November 2019
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	* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.		* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.
	* Buffers cannot be negative. It is not possible to shrink a selection polygon.		* Buffers cannot be negative. It is not possible to shrink a selection polygon.
	* When using a ~~buffer~~ clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a BUFFER clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.
	* By using the [[~~Tygron_Query_Language~~#~~Construction_polygons~~\|~~lotpolygons~~]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.		* By using the [[TQL#Construction polygons\|LOTPOLYGONS]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.

Rudolf@tygron.nl: /* Notes */

2019-11-06T15:44:48Z

Notes

← Older revision		Revision as of 15:44, 6 November 2019
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	When using buffers, take the following into consideration:		When using buffers, take the following into consideration:
	* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Constructions\|constructions]].		* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Constructions\|constructions]].
	* When a buffer clause is used to ~~enlarge~~ a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.		* When a buffer clause is used to extend a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.
	* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.		* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.
	* Buffers cannot be negative. It is not possible to shrink a selection polygon.		* Buffers cannot be negative. It is not possible to shrink a selection polygon.
	* When using a buffer clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a buffer clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.
	* By using the [[Tygron_Query_Language#Construction_polygons\|lotpolygons]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.		* By using the [[Tygron_Query_Language#Construction_polygons\|lotpolygons]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.

Rudolf@tygron.nl: /* Notes */

2019-11-06T15:43:23Z

Notes

← Older revision		Revision as of 15:43, 6 November 2019
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	==Notes==		==Notes==
	When using buffers, take the following into consideration:		When using buffers, take the following into consideration:
	* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[Constructions\|constructions]].		* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Constructions\|constructions]].
	* When a buffer clause is used to enlarge a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.		* When a buffer clause is used to enlarge a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.
	* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.		* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.

Rudolf@tygron.nl: /* How to use buffers to retrieve data */

2019-11-06T15:40:27Z

How to use buffers to retrieve data

← Older revision		Revision as of 15:40, 6 November 2019
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	To find the amount of green only in neighborhood 1:		To find the amount of green only in neighborhood 1:

	<code>SELECT_LOTSIZE_WHERE_FUNCTIONMULT_IS_GREEN_M2_AND_NEIGHBORHOOD_IS_1</code>*<br>		<code>SELECT_LOTSIZE_WHERE_FUNCTIONMULT_IS_GREEN_M2_AND_NEIGHBORHOOD_IS_1</code><br>

	To find the amount of green in neighborhood 1 ''and in an area of 50 meters around neighborhood 1'':		To find the amount of green in neighborhood 1 ''and in an area of 50 meters around neighborhood 1'':

Godelief@tygron.nl at 12:40, 6 November 2019

2019-11-06T12:40:17Z

← Older revision		Revision as of 12:40, 6 November 2019
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	==How buffers are applied==		==How buffers are applied==
	[[File:buffer_function.jpg\|300px\|thumb\|right\|~~How a~~ buffer ~~is interpreted~~ for a query ~~for LOTSIZE~~ based on a grid.]]		[[File:buffer_function.jpg\|300px\|thumb\|right\|The red line shows the buffer around the selection polygon (yellow) for a LOTSIZE query based on a grid.]]

	The BUFFER clause affects the polygon selection of the TQL query. When a query makes a selection for, for example, [[TQL#Construction polygons\|LOTSIZE]], the clauses indicate in which selection polygon you want to find the lotsize. The selection polygon is computed by the overlap of clauses such as [[TQL#Specific polygons\|AREA]] and [[TQL#Grids\|MINGRIDVALUE]]. After this selection polygon is computed, it is queried to find all the relevant lotsizes within.		The BUFFER clause affects the polygon selection of the TQL query. When a query makes a selection for, for example, [[TQL#Construction polygons\|LOTSIZE]], the clauses indicate in which selection polygon you want to find the lotsize. The selection polygon is computed by the overlap of clauses such as [[TQL#Specific polygons\|AREA]] and [[TQL#Grids\|MINGRIDVALUE]]. After this selection polygon is computed, it is queried to find all the relevant lotsizes within.

Godelief@tygron.nl: /* Notes */

2019-11-06T12:38:36Z

Notes

← Older revision		Revision as of 12:38, 6 November 2019
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	* Buffers cannot be negative. It is not possible to shrink a selection polygon.		* Buffers cannot be negative. It is not possible to shrink a selection polygon.
	* When using a buffer clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a buffer clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.
			* By using the [[Tygron_Query_Language#Construction_polygons\|lotpolygons]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.

Godelief@tygron.nl: /* Consideration when using buffers */

2019-11-06T12:36:36Z

Consideration when using buffers

← Older revision		Revision as of 12:36, 6 November 2019
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	<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>		<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>

	==~~Consideration when using buffers~~==		==Notes==
	When using buffers, take the following into consideration:		When using buffers, take the following into consideration:
	* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual constructions.		* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[Constructions\|constructions]].
	* When a buffer clause is used to ~~extends~~ a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.		* When a buffer clause is used to enlarge a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.
	* When buffering based on grids, take into account the grid size in respect ~~the~~ the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.		* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as constructions may be less likely to be in range of the grid-based data.
	* Buffers cannot be negative. It is not possible to shrink a selection polygon.		* Buffers cannot be negative. It is not possible to shrink a selection polygon.
	* When using a buffer to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a buffer clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.

← Older revision		Revision as of 15:21, 7 October 2022
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	[[File:buffer_function.jpg\|300px\|thumb\|right\|The red line shows the buffer around the selection polygon (yellow) for a LOTSIZE query based on a grid.]]		[[File:buffer_function.jpg\|300px\|thumb\|right\|The red line shows the buffer around the selection polygon (yellow) for a LOTSIZE query based on a grid.]]

	The BUFFER clause affects the polygon selection of the TQL query. When a query makes a selection for, for example, [[TQL#~~Construction~~ polygons\|LOTSIZE]], the clauses indicate in which selection polygon you want to find the lotsize. The selection polygon is computed by the overlap of clauses such as [[TQL#Specific polygons\|AREA]] and [[TQL#Grids\|MINGRIDVALUE]]. After this selection polygon is computed, it is queried to find all the relevant lotsizes within.		The BUFFER clause affects the polygon selection of the TQL query. When a query makes a selection for, for example, [[TQL#Building polygons\|LOTSIZE]], the clauses indicate in which selection polygon you want to find the lotsize. The selection polygon is computed by the overlap of clauses such as [[TQL#Specific polygons\|AREA]] and [[TQL#Grids\|MINGRIDVALUE]]. After this selection polygon is computed, it is queried to find all the relevant lotsizes within.

	The buffer is applied after computing the selection polygon, but before finding the lotsize inside the selection polygon. The selection polygon is buffered with the indicated amount to create a larger selection polygon, in which more lotsize may be found.		The buffer is applied after computing the selection polygon, but before finding the lotsize inside the selection polygon. The selection polygon is buffered with the indicated amount to create a larger selection polygon, in which more lotsize may be found.
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	==How to use buffers to write data==		==How to use buffers to write data==
	Buffers can also be used in combination with grids to conditionally write data to [[~~construction~~]]s. For example, consider a use-case where ~~constructions~~ with water nearby should be marked as "threatened".		Buffers can also be used in combination with grids to conditionally write data to [[building]]s. For example, consider a use-case where buildings with water nearby should be marked as "threatened".

	To find ~~constructions~~ with water on them:		To find buildings with water on them:

	<code>SELECT_LOTSIZE_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1</code>*<br>		<code>SELECT_LOTSIZE_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1</code>*<br>
	(*Assuming grid 4 is a [[Water Overlay]]'s [[Surface last value result type (Water Overlay)\|SURFACE_LAST_VALUE result type]], and the relevant amount of water is 10cm)		(*Assuming grid 4 is a [[Water Overlay]]'s [[Surface last value result type (Water Overlay)\|SURFACE_LAST_VALUE result type]], and the relevant amount of water is 10cm)

	How to write an attribute (THREATENED) to ~~constructions~~ with water on them:		How to write an attribute (THREATENED) to buildings with water on them:

	<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1</code>		<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1</code>

	How to update ~~constructions~~ with water not just on them, but also within 1 meter of the water:		How to update buildings with water not just on them, but also within 1 meter of the water:

	<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>		<code>UPDATE_BUILDING_THREATENED_WHERE_GRID_IS_4_AND_MINGRIDVALUE_IS_0.1_AND_BUFFER_IS_1</code>
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	==Notes==		==Notes==
	When using buffers, take the following into consideration:		When using buffers, take the following into consideration:
	* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#~~Constructions~~\|~~constructions~~]].		* Buffers only apply to selection polygons. This includes [[TQL#Specific polygons\|specific polygons]], [[TQL#Attribute polygons\|attribute polygons]], and [[TQL#Grids\|grids]], but not individual [[TQL#Buildings\|buildings]].
	* When a buffer clause is used to extend a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.		* When a buffer clause is used to extend a selection polygon, the new selection polygon includes both the original selection polygon as well as the buffer around it.
	* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as ~~constructions~~ may be less likely to be in range of the grid-based data.		* When buffering based on grids, take into account the grid size in respect to the buffer size. If the buffer size is not greater than the [[grid cell size]] some vector-based data such as buildings may be less likely to be in range of the grid-based data.
	* Buffers cannot be negative. It is not possible to shrink a selection polygon.		* Buffers cannot be negative. It is not possible to shrink a selection polygon.
	* When using a BUFFER clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.		* When using a BUFFER clause to create a selection polygon, it is not possible to automatically create an inverse selection. I.e. for a query looking for grid values higher than a certain value and a query looking for grid values lower than that same value, the selection polygons are effective complementary. However, when the queries are buffered, the two selection polygons will overlap.
	* By using the [[TQL#~~Construction~~ polygons\|LOTPOLYGONS]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.		* By using the [[TQL#Building polygons\|LOTPOLYGONS]] clause in combination with the buffer clause, it is is possible to see the created buffer selection polygon.