Where features overlap
16
votes
4answers
3k views
Separate polygons based on intersection using PostGIS
I have a PostGIS table of polygons where some intersect with one another. This is what I'm trying to do:
For a given polygon selected by id, give me all of the polygons that intersect. Basically, ...
13
votes
2answers
1k views
Identifying road intersections using PostGIS
I'm trying to identify where roads intersect each other, and to make a point at this intersection, with the number of roads that form the intersection listed.
I was wondering if there was some way ...
3
votes
2answers
413 views
How do I find the points of intersection between a small circle and a great circle?
I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle.
I found this tutorial for intersecting two great circle arcs, but ...
11
votes
5answers
3k views
How to use ST_Intersection?
Here's a quick summary about what I'm trying to do: I have 3 tables in Postgres, 'a' and 'b', each have a Polygon column, and 'c' has a Point column. What I'm trying to do here is to get the ...
2
votes
2answers
761 views
How to repair topology of a shapefile?
I performed an object-based image analysis using ENVI EX, and each of the classified features were exported as a shapefile. I transferred those shapefiles into ArcMap 10, and tried to intersect them ...
4
votes
2answers
112 views
Keep nonintersecting polygons during clip
I am using ArcMap 10. I have two datasets, one of which consists of many small contiguous polygons, and one which has many small non-contiguous polygons. The first dataset is census blocks, and the ...
3
votes
0answers
126 views
Rgeos drops associated values when intersecting polygons
I am trying to intersect two SpatialPolygonsDataFrames and get a SpatialPolygonsDataFrame as the result. Unfortunately, using the gIntersection function from rgeos (which works impressively quickly ...
8
votes
4answers
2k views
Lines that intersect vs. Lines that touch - how to distinguish?
How do I distinguish between these cases in ArcGIS 10? I am looking at the Trim Line function but that's not what I want (destructive).
Case 1: Both endpoints of a line touch another line
Case 2: ...
6
votes
2answers
2k views
How to create a new layer from overlap between two layers?
I'm new to desktop GIS, and will try to ask while lacking the proper terms from the GIS lingo:
If QGIS was like Photoshop I would like to make a selection from one layer, and then match that ...
4
votes
1answer
273 views
Line intersection with circle on a sphere (globe or earth)
How can I find the intersection point of a line and a circle on a sphere (on earth)
Please, if any one knows a good solution help.
Thanks in response :)
-2
votes
1answer
171 views
Postgis error on select all intersetcs of a polygon [closed]
i can get all polygon on intersects this:-7.9245860488441 -37.122384500713,-7.9245860488441 -37.11904223938,-7.9233955716106 -37.1187601948
SELECT *
FROM propriedades
WHERE ST_Intersects(
...
