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Questions tagged [st-difference]

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4
votes
2answers
103 views

Find what polygons are not fully covered by union of polygons from another layer in PostGIS

I have two tables in a PostGIS database >>> select postgis_version(); "2.5 USE_GEOS=1 USE_PROJ=1 USE_STATS=1" One represents the country borders and another one is administrative ...
0
votes
0answers
150 views

Function in R to get difference between two sets of polygons comparable in speed to QGIS

I have two very large polygon shapefiles for which I need to calculate the difference between the two shapefiles. One is a shapefile of forest polygons, the other is a shapefile of road polygons. I ...
1
vote
0answers
60 views

Uploading overlapping contours into PostgreSQL?

I've got 100+ shapefiles of contours with the following fields: class (text) altitude (double) geom (geometry) And I need to upload them into a single table in PostgreSQL. Now, I've managed to ...
1
vote
1answer
127 views

st_difference (erase overlapped feature) line from polygon

I have two layers. One is MultiLineString and the other is MultiPolygon. I am trying to erase lines that are on the polygon feature With QGIS difference tool, it worked just fine This is my code and ...
0
votes
3answers
326 views

Increase spatial query performance (st_difference)

I have two link tables one is 9029 rows (and let's say this table is A) and the other is 11698 rows (and this table is B) the both tables are road link and A is for tunnel link and B is road link ...
1
vote
0answers
172 views

ESRI Polygon cutouts (neg. space) become multiple layers in PostGIS

I have a single MULTIPOLYGON from ESRI ArcGIS with 10,000+ sub-polygons in a Shapefile, some having > 1.4 million vertices. I'm importing the data into PostGIS (ogr2ogr or shp2pgsql, same results) so ...
2
votes
1answer
151 views

Bringing two lines together and getting their difference

In the photo there are two lines that are parallel to each other. I want to bring them at same coordinates and carry out the difference between them, which will be the small part of red line from the ...
4
votes
0answers
64 views

ST_Difference() PostGIS returns weird results [duplicate]

I'm trying to use the postgis's st_difference() function, but with no luck. I have a layer of polygons A And a layer of Polygons B What I want to achieve is this (created with QGIS algorithm): ...