All Questions
71
questions
2
votes
2
answers
99
views
How to prevent duplicates from being generated in Spatial Join in PostGIS
I'm trying to create a spatial view which meets the following criteria:
Sentinel hotspots registered within 2km of powerline (feeder)
AND
QRFS point located within 4km radius of sentinel hotspots
AND
...
- 21.9k
1
vote
1
answer
120
views
PostGIS Multi-Ring Buffers Around Lines
I would like to create a multi-ring buffer around a stream network and add a default floating value to each each buffer ring. I currently have the following SQL query:
CREATE TABLE public....
- 995
3
votes
1
answer
146
views
Buffer accuracy in virtual layer differs from accuracy in PostGIS view
I used virtual layer query to create a buffer for a point as this allowed me to transform its SRID using the PostGIS function ST_Transform, which is not possible with the ready-to-use Buffer algorithm ...
- 887
1
vote
0
answers
33
views
PostGIS cut polygon by line from street side [closed]
I have this Polygon
and this Lines from the streets of Germany.
I tried many hours with ST_Split or ST_Difference to cut the polygons by the street lines but it wasnt possible.
My intention is to ...
- 31
0
votes
0
answers
73
views
ST_DWithin with variable distance in PostGIS
I have a table of two columns:
Polylines (Linestrings) geometry coordinates.
Buffers: distance in kilometers.
The table contains about 1000 entries.
Using PostGIS "ST_DWithin" or any ...
6
votes
4
answers
298
views
Buffer with PostGIS in the form of a pentagon or hexagon
In PostGIS, the ST_Buffer function allows a user to specify the segements per quadrant. However, only polygons with multiples of 4 (4, 8, 12, 16, etc) are allowed.
How would you buffer a point to a ...
- 167
2
votes
1
answer
440
views
St_buffer then reverse st_buffer
A slightly theoretical PostGIS question. If you have a polygon, perform a positive buffer on it, then perform the same buffer operation but negative, you end up with a slightly different polygon than ...
- 533
0
votes
0
answers
57
views
Using PostGIS operations
I'm new on PostGIS
I have this
The orange ones are buffers, the red dots are the centroids of each brown polygon
So I've tried to cover the brown polygons by making buffers of the centroids (red dots)...
2
votes
1
answer
240
views
Create union of buffers in PostGIS visible in QGIS
I would like to merge overlapping buffers created in PostGIS and have as many polygons as there are not overlapping merged buffers, that can be viewed in QGIS.
The answer of Creating dissolved buffers ...
- 63
0
votes
0
answers
2k
views
ST_Buffer in meters from 4326 point table
I would like to create 100 meters circle buffers in a UTM projection from a point table whose SRID is EPSG:4326 and keeping the id column.
I wonder what is the straightest way. Is that possible to get ...
- 63
1
vote
2
answers
124
views
Drawing a buffer from a POINT and a value for Acreage
We have a situation where we get a single lat/long point and a value for "acreage", and we need to draw a polygon circle that is roughly the size that the acreage value implies. What we have ...
5
votes
2
answers
1k
views
PostGIS: Single side ST_Buffer of linestring produces strange output
In the example below I have a linestring PostGIS table (in black and yellow) and a single sided ST_Buffer output polygon (in red). The buffer distance is based on an attribute value stored in the ...
- 1,839
5
votes
1
answer
217
views
Count number of points outside of buffer
I'm trying to count the total points outside of a buffer zone using PostgreSQL. The intention is to find all of the schools that do not fall within a 2-mile radius of libraries.
I've either gotten ...
- 51
2
votes
1
answer
1k
views
Select points within a buffer around a line
Working with PostgreSQL. I have a Table with streets (Linestrings), and a Table with accidents (Points). The streets are divided into sections. I want to find the accidents within 50m around a certain ...
1
vote
0
answers
346
views
Creating a dissolved buffer layer in PostgreSQL/PostGIS
I have got a MultiPolygons layer to which I want to create 10 meter buffer around and then dissolve. All data are having SRID 4326.
I am new to PostgreSQL/PostGIS. I am drifting around the ST_Buffer ...
- 41