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Is it possible to convert Polygon to centerline linestring?

Finding centrelines from polygons in QGIS?Create a center line between 2 polyline - QGISCreate centerline from multi-digitized roadway lines Qgis 2.18Calculating average width of polygon?Convert polyline to polygon Using ArcObjectsIntersection between polylines feature to polygon in QGISConvert a line to polygonConvert a group of lines into a single polygone to style itConverting polygon to line feature in ArcGIS Desktop?Polygon to polyline conversionConverting polyline to polygon without 'Feature to Polygon'Calculate Polygon Centerline with a LeastCostPath approachConvert multiple lines into a polygon in QGIS

3

I have a Polygon which I want to convert to centerline linestring.

IMAGE 1

I used the Vector to convert to Polyline but they are not center line as under:

VECTOR TOOL

IMAGE 2

Polyline created by the above tool is not centerline polyline.

IMAGE 3

What I am expecting to get is as under (centerline per road, instead of the lines on the side of the road[Image 3]):

IMAGE 4

qgis polygon line

share|improve this question

asked Jul 26 '18 at 23:22

DufferDuffer

767

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  See this post: gis.stackexchange.com/questions/33887/…
  
  – Cushen
  Jul 27 '18 at 0:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I tried those options but it didnt work. The model implemented by underdark. Also didnt work, it returned empty shape file.
  
  – Duffer
  Jul 27 '18 at 1:22
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  OpenJUMP has a skeletonizer plugin.
  
  – user30184
  Jul 27 '18 at 3:55
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The skeletonizer plugin in OpenJUMP needs me to add an input PointSHape Filealong with the Polygon. Hence I cant use it. I need something similar to pro.arcgis.com/en/pro-app/tool-reference/topographic-production/…
  
  – Duffer
  Jul 27 '18 at 4:39
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If you want to stay in QGIS environment, try HCMGIS plugin. (Geometry processing | Skeleton / Medial Axis).. it requires QGIS3.0+ though.
  
  – Kazuhito
  Jul 27 '18 at 14:23
  
  
  

  
  
  
  

 | 
show 15 more comments

3

I have a Polygon which I want to convert to centerline linestring.

IMAGE 1

I used the Vector to convert to Polyline but they are not center line as under:

VECTOR TOOL

IMAGE 2

Polyline created by the above tool is not centerline polyline.

IMAGE 3

What I am expecting to get is as under (centerline per road, instead of the lines on the side of the road[Image 3]):

IMAGE 4

qgis polygon line

share|improve this question

asked Jul 26 '18 at 23:22

DufferDuffer

767

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  See this post: gis.stackexchange.com/questions/33887/…
  
  – Cushen
  Jul 27 '18 at 0:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I tried those options but it didnt work. The model implemented by underdark. Also didnt work, it returned empty shape file.
  
  – Duffer
  Jul 27 '18 at 1:22
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  OpenJUMP has a skeletonizer plugin.
  
  – user30184
  Jul 27 '18 at 3:55
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The skeletonizer plugin in OpenJUMP needs me to add an input PointSHape Filealong with the Polygon. Hence I cant use it. I need something similar to pro.arcgis.com/en/pro-app/tool-reference/topographic-production/…
  
  – Duffer
  Jul 27 '18 at 4:39
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If you want to stay in QGIS environment, try HCMGIS plugin. (Geometry processing | Skeleton / Medial Axis).. it requires QGIS3.0+ though.
  
  – Kazuhito
  Jul 27 '18 at 14:23
  
  
  

  
  
  
  

 | 
show 15 more comments

I have a Polygon which I want to convert to centerline linestring.

IMAGE 1

I used the Vector to convert to Polyline but they are not center line as under:

VECTOR TOOL

IMAGE 2

Polyline created by the above tool is not centerline polyline.

IMAGE 3

What I am expecting to get is as under (centerline per road, instead of the lines on the side of the road[Image 3]):

IMAGE 4

qgis polygon line

share|improve this question

asked Jul 26 '18 at 23:22

DufferDuffer

767

share|improve this question

asked Jul 26 '18 at 23:22

DufferDuffer

767

share|improve this question

asked Jul 26 '18 at 23:22

DufferDuffer

767

asked Jul 26 '18 at 23:22

DufferDuffer

767

asked Jul 26 '18 at 23:22

DufferDuffer

767

1 Answer
1

active

oldest

votes

1

Answer: You can.
Good afternoon, Daffer, I found time for you and hurry to help you :-).
My answer is now practical.

The original data and table names are fictitious, do not forget to rename them with reference to your example.

Sit in my car and go together to the stop - the "center line of the road."

The initial geodata are polygons of a road network with a width of about 11 m in the EPSG: 4326 coordinate system, broken into segments, see Fig. 1.

1) In a convenient way for you, create a negative buffer, for example in PGAdmin:

create table buf_negative as
SELECT ST_Buffer (geom, -0.000045) as geom
FROM buf_dump;

or in QGIS tools: "Vector-Geoprocessing-Buffer Zones".
Thus, we reduced the width of the roads from 11 m to 1 m, see Fig.2

2) Convert the negative buffer (1 m) into lines, for example with QGIS tools:
"Vector-Processing geometry-polygons in a line" result see Fig. 3

3) Extract from the lines of the point, for example with the QGIS tools: "Vector-Processing geometry-Extract nodes", the result see Fig. 4

4) Create point buffers from them, so that they intersect each other and extract centroids from adjacent buffers, the result is shown in Fig. 5
(centroids are red dots)

5) From the centroid points, create the Delaunay Triangulation, for example with the QGIS tools: "Vector-Processing geometry-Delaunay triangulation", and trim the result with your 1 m negative buffer polygons, see the result of Fig. 6

6) Blast the lines into segments, for example, using QGIS Desktop with GRASS tools: "Data Analysis - Lines-Explode Lines", see Fig. 7

7) Run the following script in PGAdmin:

create table buf_centre_ln as
SELECT ST_Intersection (a.geom, b.geom) AS geom
FROM explode_ln as a, buf_negative as b
WHERE ST_Within (a.geom, b.geom);


see the result in Fig. 8

9) Remove duplicating lines and do with the center lines, whatever,

we arrived, your stop, it's time to say goodbye,
respectfully

share|improve this answer

edited 2 hours ago

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

add a comment | 

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1

Answer: You can.
Good afternoon, Daffer, I found time for you and hurry to help you :-).
My answer is now practical.

The original data and table names are fictitious, do not forget to rename them with reference to your example.

Sit in my car and go together to the stop - the "center line of the road."

The initial geodata are polygons of a road network with a width of about 11 m in the EPSG: 4326 coordinate system, broken into segments, see Fig. 1.

1) In a convenient way for you, create a negative buffer, for example in PGAdmin:

create table buf_negative as
SELECT ST_Buffer (geom, -0.000045) as geom
FROM buf_dump;

or in QGIS tools: "Vector-Geoprocessing-Buffer Zones".
Thus, we reduced the width of the roads from 11 m to 1 m, see Fig.2

2) Convert the negative buffer (1 m) into lines, for example with QGIS tools:
"Vector-Processing geometry-polygons in a line" result see Fig. 3

3) Extract from the lines of the point, for example with the QGIS tools: "Vector-Processing geometry-Extract nodes", the result see Fig. 4

4) Create point buffers from them, so that they intersect each other and extract centroids from adjacent buffers, the result is shown in Fig. 5
(centroids are red dots)

5) From the centroid points, create the Delaunay Triangulation, for example with the QGIS tools: "Vector-Processing geometry-Delaunay triangulation", and trim the result with your 1 m negative buffer polygons, see the result of Fig. 6

6) Blast the lines into segments, for example, using QGIS Desktop with GRASS tools: "Data Analysis - Lines-Explode Lines", see Fig. 7

7) Run the following script in PGAdmin:

create table buf_centre_ln as
SELECT ST_Intersection (a.geom, b.geom) AS geom
FROM explode_ln as a, buf_negative as b
WHERE ST_Within (a.geom, b.geom);


see the result in Fig. 8

9) Remove duplicating lines and do with the center lines, whatever,

we arrived, your stop, it's time to say goodbye,
respectfully

share|improve this answer

edited 2 hours ago

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

add a comment | 

1

Answer: You can.
Good afternoon, Daffer, I found time for you and hurry to help you :-).
My answer is now practical.

The original data and table names are fictitious, do not forget to rename them with reference to your example.

Sit in my car and go together to the stop - the "center line of the road."

The initial geodata are polygons of a road network with a width of about 11 m in the EPSG: 4326 coordinate system, broken into segments, see Fig. 1.

1) In a convenient way for you, create a negative buffer, for example in PGAdmin:

create table buf_negative as
SELECT ST_Buffer (geom, -0.000045) as geom
FROM buf_dump;

or in QGIS tools: "Vector-Geoprocessing-Buffer Zones".
Thus, we reduced the width of the roads from 11 m to 1 m, see Fig.2

2) Convert the negative buffer (1 m) into lines, for example with QGIS tools:
"Vector-Processing geometry-polygons in a line" result see Fig. 3

3) Extract from the lines of the point, for example with the QGIS tools: "Vector-Processing geometry-Extract nodes", the result see Fig. 4

4) Create point buffers from them, so that they intersect each other and extract centroids from adjacent buffers, the result is shown in Fig. 5
(centroids are red dots)

5) From the centroid points, create the Delaunay Triangulation, for example with the QGIS tools: "Vector-Processing geometry-Delaunay triangulation", and trim the result with your 1 m negative buffer polygons, see the result of Fig. 6

6) Blast the lines into segments, for example, using QGIS Desktop with GRASS tools: "Data Analysis - Lines-Explode Lines", see Fig. 7

7) Run the following script in PGAdmin:

create table buf_centre_ln as
SELECT ST_Intersection (a.geom, b.geom) AS geom
FROM explode_ln as a, buf_negative as b
WHERE ST_Within (a.geom, b.geom);


see the result in Fig. 8

9) Remove duplicating lines and do with the center lines, whatever,

we arrived, your stop, it's time to say goodbye,
respectfully

share|improve this answer

edited 2 hours ago

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

add a comment | 

Answer: You can.
Good afternoon, Daffer, I found time for you and hurry to help you :-).
My answer is now practical.

The original data and table names are fictitious, do not forget to rename them with reference to your example.

Sit in my car and go together to the stop - the "center line of the road."

The initial geodata are polygons of a road network with a width of about 11 m in the EPSG: 4326 coordinate system, broken into segments, see Fig. 1.

1) In a convenient way for you, create a negative buffer, for example in PGAdmin:

create table buf_negative as
SELECT ST_Buffer (geom, -0.000045) as geom
FROM buf_dump;

or in QGIS tools: "Vector-Geoprocessing-Buffer Zones".
Thus, we reduced the width of the roads from 11 m to 1 m, see Fig.2

2) Convert the negative buffer (1 m) into lines, for example with QGIS tools:
"Vector-Processing geometry-polygons in a line" result see Fig. 3

3) Extract from the lines of the point, for example with the QGIS tools: "Vector-Processing geometry-Extract nodes", the result see Fig. 4

4) Create point buffers from them, so that they intersect each other and extract centroids from adjacent buffers, the result is shown in Fig. 5
(centroids are red dots)

5) From the centroid points, create the Delaunay Triangulation, for example with the QGIS tools: "Vector-Processing geometry-Delaunay triangulation", and trim the result with your 1 m negative buffer polygons, see the result of Fig. 6

6) Blast the lines into segments, for example, using QGIS Desktop with GRASS tools: "Data Analysis - Lines-Explode Lines", see Fig. 7

7) Run the following script in PGAdmin:

create table buf_centre_ln as
SELECT ST_Intersection (a.geom, b.geom) AS geom
FROM explode_ln as a, buf_negative as b
WHERE ST_Within (a.geom, b.geom);


see the result in Fig. 8

9) Remove duplicating lines and do with the center lines, whatever,

we arrived, your stop, it's time to say goodbye,
respectfully

share|improve this answer

edited 2 hours ago

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

share|improve this answer

edited 2 hours ago

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

answered Sep 9 '18 at 16:32

CyrilCyril

7571214

answered Sep 9 '18 at 16:32

CyrilCyril

7571214