Enlargement in one dimension to bigger polygon

Question

I have areas (polygon) in the streets (polygons).

I want to enlagre the parallel segment to an other polygon to touch it. And so creating this new polygons.

There is a lot of new alogithms in field calculator. Maybe processing alorithms could be a solution or Python or GRASS. I don't know which way to choose.

At this time, i try this way :

1. Cut areas by street polygons
2. Join attributes by location to grab street polygon id in the area
3. Polygon to lines
4. Explode lines
5. Maybe ** IF segment is < 0-45 degrees THEN segment is extended to road polygons ( exploded too ?)**

Polygons to lines

Answer 1

If I understand correctly, see the source data in Figure 1; The solution is as follows: 1) In QGIS, run the Vector tool - "Geometry processing" - "Extract nodes" onto the polygon being processed, the result is shown in figure 2;

2) If you have rectangular polygons, then run in pgAdmin a query for two opposite points belonging to the polygon: create table exper_poi1 as SELECT ST_ClosestPoint (my_line_exper.geom, exper_poi.geom) FROM my_line_exper, exper_poi WHERE exper_poi.gid = 1; and combine them into one layer (table), for example exper_poi_all. (in my experiment there are 4 such points, and not 2, since I do not have a rectangular polygon), the result is shown in Figure 3;

3) In QGIS, on your exper_poi_all table, run the Delaunay Triangulation tool and get the following table, for example: exper_poi_triangl, see figure 4;

4) In QGIS in the "Pencil" editing mode in the exper_poi_triangl table, select all triangles that fall into the area of interest, use the "Vector" tool - "Geoprocessing" - "Merge by feature" (check "selected objects only" "Classification" - for all reasons) result exper_poly see figure 5;

Good luck, with respect