Tagged Questions
2
votes
2answers
32 views
PostGIS - ST_Collect but only include POLYGONs not POINTs?
In PostGSI, is there anyway to turn a GEOMETRYCOLLECTION into a MULTIPOLYGON by dropping all non-POLYGONs/non-MULTIPOLYGONs?
I'm doing a query that cuts a bunch of geometries (using ST_Intersection) ...
6
votes
2answers
76 views
PostGIS Union Between Two Tables, Preserving Attributes
I'm trying to union US State level upper- and lower-level government boundaries in such a way that generates one PostGIS table with both the upper and lower level names for each shape.
In my example ...
2
votes
1answer
92 views
Why doesn't PostGIS use gist index when doing a ST_DUMP(ST_UNION)?
My query:
DROP TABLE IF EXISTS tmp;
CREATE TEMP TABLE tmp AS SELECT *, ST_BUFFER(the_geom::GEOGRAPHY, 3000)::GEOMETRY AS buffer FROM af_modis_master LIMIT 20000;
CREATE INDEX idx_tmp_the_geom ON tmp ...
5
votes
1answer
145 views
PostGIS - Why are my ST_Union results (stored in a new table) outputting as points and not polygons?
I've decided to move to PostGIS to merge polygons rather than spend hours doing in in QGIS. However, I'm hitting an issue where the results of an ST_Union query are being stored, or at least outputted ...
4
votes
2answers
148 views
PostGIS algorithm to unite points of two geometries that are within specified radius
I want to find an PostGIS algorithm to unite points of two geometries that are "near" to each other.
That is: I want a function, that takes as input two geometries, and returns 1 geometry, that ...
2
votes
2answers
286 views
Merge polygons in postgis
I have a hand-digitized coverage stored in postgis. There, I have a few shiver-polygons I would like to get rid of by including them into one of the neighbouring polygons.
are there any commands that ...
4
votes
3answers
117 views
Trying to combine nearby points into a polygon
We have collected millions of cell phone strength readings. I am trying to group points of the same strenght that are within a distance of each other in to a polygon. I asked on the
postgis mailing ...
4
votes
2answers
230 views
memory issue when trying to buffer/union large dataset using postgis
I am trying to generated a dissolved buffer of a large point dataset (Ideally 29 million points - Address data in Great-Britain, but I receive the data by chunks of 1 million points, so these could be ...
