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PostGIS function to move a polygon to centre over new point coordinates

Best way to store polygon geospatial data in postgreSQL?Postgis create polygon extent/convex hull from spatial tablePolygon centroid coordinates update errorProblem with PostgreSQL View layer in QGISInconsistent results in ST_DistanceCreating shapes/lines from geo coordinates in postgisProgrammatically move points in front of building polygons in PostGISCreate a Rectangle around a point in PostGISChecking if point lies with GeoJSON Polygon in PostgreSQL?Point Data to journey linestrings - PostGIS

2

Background:

(Note: I am trying to do as much of this as possible in PostGIS/PostgreSQL)

I have a PostgreSQL table containing location data of an aircraft in orbit around a city. Every second a new row is added with new position data.

From this table I have created a view which shows a constantly updating point of only the current position. This view therefore contains only one row.

The Task:

I have created a custom polygon in a different table, which acts as a buffer around the current position point. I want to reposition/move this polygon to always be centred over the constantly updating current position coordinates. Does anyone know how to do this? I have already experimented with rotate and scale. I am happy with them. It is moving the polygon that is confusing me.

I have tried creating a view that uses ST_Translate for the polygon, however from my understanding, this function only moves coordinates by a fixed amount from the origin. It doesn’t allow me to specify exactly what lon lat coordinates I want it to move to. Does anyone know a function/how to move a polygon to new coordinates, centred on a point? Again, I am trying to achieve this from PostGIS.

qgis postgis postgresql polygon move

share|improve this question

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  ST_Translate moves a geometry by a specified amount in x, y and, optionally, z directions. So, to calculate how much you need to move the polygon, calculate the change in x and y between your new point and the centroid of the polygon
  
  – John Powell
  1 hour ago
  

  
  
  
  

add a comment | 

2

Background:

(Note: I am trying to do as much of this as possible in PostGIS/PostgreSQL)

I have a PostgreSQL table containing location data of an aircraft in orbit around a city. Every second a new row is added with new position data.

From this table I have created a view which shows a constantly updating point of only the current position. This view therefore contains only one row.

The Task:

I have created a custom polygon in a different table, which acts as a buffer around the current position point. I want to reposition/move this polygon to always be centred over the constantly updating current position coordinates. Does anyone know how to do this? I have already experimented with rotate and scale. I am happy with them. It is moving the polygon that is confusing me.

I have tried creating a view that uses ST_Translate for the polygon, however from my understanding, this function only moves coordinates by a fixed amount from the origin. It doesn’t allow me to specify exactly what lon lat coordinates I want it to move to. Does anyone know a function/how to move a polygon to new coordinates, centred on a point? Again, I am trying to achieve this from PostGIS.

qgis postgis postgresql polygon move

share|improve this question

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  ST_Translate moves a geometry by a specified amount in x, y and, optionally, z directions. So, to calculate how much you need to move the polygon, calculate the change in x and y between your new point and the centroid of the polygon
  
  – John Powell
  1 hour ago
  

  
  
  
  

add a comment | 

Background:

(Note: I am trying to do as much of this as possible in PostGIS/PostgreSQL)

I have a PostgreSQL table containing location data of an aircraft in orbit around a city. Every second a new row is added with new position data.

From this table I have created a view which shows a constantly updating point of only the current position. This view therefore contains only one row.

The Task:

I have created a custom polygon in a different table, which acts as a buffer around the current position point. I want to reposition/move this polygon to always be centred over the constantly updating current position coordinates. Does anyone know how to do this? I have already experimented with rotate and scale. I am happy with them. It is moving the polygon that is confusing me.

I have tried creating a view that uses ST_Translate for the polygon, however from my understanding, this function only moves coordinates by a fixed amount from the origin. It doesn’t allow me to specify exactly what lon lat coordinates I want it to move to. Does anyone know a function/how to move a polygon to new coordinates, centred on a point? Again, I am trying to achieve this from PostGIS.

qgis postgis postgresql polygon move

share|improve this question

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 42 mins ago

Vince

14.6k32748

edited 42 mins ago

Vince

14.6k32748

asked 1 hour ago

DemusDemus

111

New contributor

Demus is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 1 hour ago

DemusDemus

111

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3

The easiest would be to have your polygon centered on (0;0) and to use st_translate using the target point X;Y as the delta X and delta Y.

Using any polygon, you would compute the delta by removing the polygon centroid X and Y from the target point X and Y:

WITH pt AS (SELECT 'point(-75.5 47.2)'::geometry geom),

poly AS (SELECT 'polygon((-70 41, -71 41, -71 40,-70 40, -70 41))'::geometry geom)

SELECT st_asText(

         ST_TRANSLATE(

             poly.geom, 

             st_x(pt.geom) - st_x(st_centroid(poly.geom)), 

             st_y(pt.geom) - st_y(st_centroid(poly.geom))

           )

        )

FROM pt, poly;



                        st_astext

---------------------------------------------------------

 POLYGON((-75 47.7,-76 47.7,-76 46.7,-75 46.7,-75 47.7))

(1 row)

share|improve this answer

answered 1 hour ago

JGHJGH

12.4k21136

add a comment | 

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3

The easiest would be to have your polygon centered on (0;0) and to use st_translate using the target point X;Y as the delta X and delta Y.

Using any polygon, you would compute the delta by removing the polygon centroid X and Y from the target point X and Y:

WITH pt AS (SELECT 'point(-75.5 47.2)'::geometry geom),

poly AS (SELECT 'polygon((-70 41, -71 41, -71 40,-70 40, -70 41))'::geometry geom)

SELECT st_asText(

         ST_TRANSLATE(

             poly.geom, 

             st_x(pt.geom) - st_x(st_centroid(poly.geom)), 

             st_y(pt.geom) - st_y(st_centroid(poly.geom))

           )

        )

FROM pt, poly;



                        st_astext

---------------------------------------------------------

 POLYGON((-75 47.7,-76 47.7,-76 46.7,-75 46.7,-75 47.7))

(1 row)

share|improve this answer

answered 1 hour ago

JGHJGH

12.4k21136

add a comment | 

3

The easiest would be to have your polygon centered on (0;0) and to use st_translate using the target point X;Y as the delta X and delta Y.

Using any polygon, you would compute the delta by removing the polygon centroid X and Y from the target point X and Y:

WITH pt AS (SELECT 'point(-75.5 47.2)'::geometry geom),

poly AS (SELECT 'polygon((-70 41, -71 41, -71 40,-70 40, -70 41))'::geometry geom)

SELECT st_asText(

         ST_TRANSLATE(

             poly.geom, 

             st_x(pt.geom) - st_x(st_centroid(poly.geom)), 

             st_y(pt.geom) - st_y(st_centroid(poly.geom))

           )

        )

FROM pt, poly;



                        st_astext

---------------------------------------------------------

 POLYGON((-75 47.7,-76 47.7,-76 46.7,-75 46.7,-75 47.7))

(1 row)

share|improve this answer

answered 1 hour ago

JGHJGH

12.4k21136

add a comment | 

The easiest would be to have your polygon centered on (0;0) and to use st_translate using the target point X;Y as the delta X and delta Y.

Using any polygon, you would compute the delta by removing the polygon centroid X and Y from the target point X and Y:

WITH pt AS (SELECT 'point(-75.5 47.2)'::geometry geom),

poly AS (SELECT 'polygon((-70 41, -71 41, -71 40,-70 40, -70 41))'::geometry geom)

SELECT st_asText(

         ST_TRANSLATE(

             poly.geom, 

             st_x(pt.geom) - st_x(st_centroid(poly.geom)), 

             st_y(pt.geom) - st_y(st_centroid(poly.geom))

           )

        )

FROM pt, poly;



                        st_astext

---------------------------------------------------------

 POLYGON((-75 47.7,-76 47.7,-76 46.7,-75 46.7,-75 47.7))

(1 row)

share|improve this answer

answered 1 hour ago

JGHJGH

12.4k21136

WITH pt AS (SELECT 'point(-75.5 47.2)'::geometry geom),

poly AS (SELECT 'polygon((-70 41, -71 41, -71 40,-70 40, -70 41))'::geometry geom)

SELECT st_asText(

         ST_TRANSLATE(

             poly.geom, 

             st_x(pt.geom) - st_x(st_centroid(poly.geom)), 

             st_y(pt.geom) - st_y(st_centroid(poly.geom))

           )

        )

FROM pt, poly;



                        st_astext

---------------------------------------------------------

 POLYGON((-75 47.7,-76 47.7,-76 46.7,-75 46.7,-75 47.7))

(1 row)

share|improve this answer

answered 1 hour ago

JGHJGH

12.4k21136

answered 1 hour ago

JGHJGH

12.4k21136

answered 1 hour ago

JGHJGH

12.4k21136