Questions tagged [intersection]

Use this tag when asking questions related to where features overlap.

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R- Quickest/most efficient way to parallelize/break up an overlay of points to large grid (or spatial join)? [closed]

I have a shapefile of roughly 200,000 randomly spaced points that I need to overlay with a grid to find which specific cells the points fall within (will aggregate/average the points up later). This ...
4
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2answers
3k views

Angle at intersection point from two Lines

I would like to find the angle of two lines at their intersection point. In my opinion it is the azimuth I'm looking for, right? So I'm using Python with shapely for finding the intersection and ...
3
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1answer
53 views

Calculating polygon attribute based on intersection with grid in QGIS

I'm trying to use QGIS to profiling polygons in a layer. There is also another grid layer, each grid contains its own demographics information. Assume the demographics are evenly distributed within ...
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0answers
43 views

Finding differences between polygons in PostGIS

I have another redistricting question. The datasets and queries available on my GitHub, but I will include the queries here, too. I am working on two complete datasets: 1) A PLAN - composed of ...
6
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3answers
357 views

Looping through table to get single intersection from N>2 geometries using PostGIS?

It's really clear how to apply ST_Intersection when you have only two geometries. But I am struggling with the situation where you have N>2 shapes and you want to compute a single one that represents ...
3
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1answer
39 views

Calculating intersection angles of multiple polylines QGIS

I have one vector layer of multiple polylines that intersect each other in QGIS. What I want to do: calculate all intersections angles (2-ray, 3-ray, 4-ray and 5-ray types) in this vector layer. What ...
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1answer
43 views

AGOL Web App - user selects a polygon and finds Web Maps that intersect it

I'm working on an ArcGIS Online Web App. Basically what I want the user to be able to do is: Select a state from a basic US state polygon map From that state selection, the user then chooses a ...
0
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1answer
179 views

Finding line segment between line intersections

Given 1 non-self-intersecting line (red) and 2 other non-self-intersecting lines (light-green), what is the best way to find the coordinates of the line in between the 2 intersections? I threw this ...
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1answer
54 views

Saving borough boundaries as MultiLineStrings or MultiPolygons?

I am creating a database in PostGIS and I have a column that will save the boundaries of boroughs. The app will later query the database, asking what points, lines or polygons are inside those ...
2
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1answer
1k views

ST_Intersects incorrectly returning false in PostGIS

I have a shapefile created from ArcMap that contains about 400 geometry's. I've added this shapefile into PostGIS using the shp2pgsql tool. I am trying to use the ST_Intersects function to determine ...
1
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1answer
31 views

Finding the overlap between two rasters based on pixel values

I'm trying to find the intersection of two rasters. Raster A has the probability of a fish existing in each pixel and Raster B has the probability of a different fish existing in the same space. I ...
4
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1answer
2k views

Optimizing ST_Within query to count lightning occurrences inside country [closed]

I just started learning PostGIS, and right now i'm trying to count the number of lightning strikes in my country (Brazil in this case). I have the following tables: earth_feed --> This holds the ...
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0answers
10 views

Add intersection coordinates to the Linestring using Shapely [duplicate]

I have two line strings as shown in the picture below. Blue and green. How to add the coordinates of the orange line(orange dots) to the green line and make it a single new line using Shapely ...
2
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1answer
30 views

Split linestring by selecting two points in OpenLayers?

I have a project where people can drag and drop a gpx file. This results in a multilinestring. People should be able to take a piece of their route and submit that. I was thinking of letting the user ...
2
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1answer
53 views

Perform intersection using a TRIGGER

I've two geometry table inside my DB: buffer: id INTEGER SERIAL PRIMARY KEY, geom POLYGON polygons: geom MULTIPOLYGON I need have the intersection between buffer and polygons and I will do this ...
3
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2answers
818 views

No intersection found between intersecting polygons [closed]

I'm using two geographies: one is made up of small areas (about 2200), the other large areas (about 70). Both cover all of Australia, and the small areas are not necessarily nested inside large areas. ...
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0answers
19 views

Intersection between two polygons using GeoDjango

I've three models: class Buffer(models.Model): geom = models.PolygonField() class ImportedPolygons(models.Model): geom = models.MultiPolygonField() class IntersectionOutput(models.Model): ...
1
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1answer
25 views

Improving performance of shapely crosses

I am unsure if this is the fastest way to test if LineStrings cross each other. Is there a better method. for line_1, line_2, in itertools.combinations(lines, 2): crosses = line_1.crosses(line_2) ...
2
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0answers
38 views

Clip completely overlapping polygon(s)

The shapefile that I'm working with (in QGIS) has over more than 250k polygons. But unfortunately a lot of the polygons are overlapping. The focus of my challenge is to delete or clip the polygon ...
1
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1answer
69 views

Line and polygon intersection in GeoPandas/Python

I am trying to intersect two GeoPandas data frames, the first one is the street data (streets) and the second one is a buffer (polygon) around a point (buffer). I want to find the intersection of ...
2
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1answer
38 views

Counting points between two intersections: Roadway Network

I have a roadway network as a line feature and crashes as point features. I need to count the number of points that lie between two intersections of roadways. The biggest problem is the road is also ...
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0answers
27 views

Clean up self-intersecting polylines in QGIS?

I have GPS data that contains self-intersections. This happens when someone walks around on "the same spot". Is there a way to clean up these in QGIS? I tried Smooth but that did not do the trick.
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0answers
29 views

Identifying line intersection in QGIS [closed]

I have 1 shp line, I want to determine the intersection positions of the roads at 4 the intersection. I used "intersection point at the road" but it gave an unexpected result (picture 1) I want to ...
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0answers
25 views

Adjecency matrix with road intersaction to the power of 3

I got the following code: line_gdf = Crewe.iloc[0:2500] ma = line_gdf.geometry.apply(lambda g: line_gdf.intersects(g)) lll = ma < 1 # Where values are low ma[lll] = 0.0001 # All low values ...
2
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1answer
2k views

Fast intersection of a list of polygons with a bounding polygon using Shapely

I have a list of Shapely polygons which I need to find the intersection of each with a bounding Shapely polygon. Not all the polygons in the list cross the boundary of the bounding polygon so I only ...
2
votes
1answer
30 views

PostGIS Recursively Finding Intersections of Polygons to Determine Clusters

My dataset currently contains about 15.000 buildings which partially touch each other. The objective is that those which do touch should belong to a cluster. This "basically" works but the main issue ...
2
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1answer
279 views

Finding shortest distance from point(s) to number of polygons at varying angles using shapely?

My aim is to calculate the distance a point is from land in Python, trying to replicate the functionality of fetchR. Given an origin and distance, I create shapely LineStrings which radiate out from ...
0
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2answers
51 views

Identifying which lines cross building polygons using ArcMap?

I have the following lines generated from coordinates with XY to Line. I would like to select and delete the lines which cross and are contained within the buildings. I need to do this to find the ...
2
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0answers
35 views

PostGIS intersected polygon fails on contains

I have two functions, first I check if a polygon is within a defined polygon. If it's not, but on the border, I cut it with ST_Intersection, and get a new polygon. If I check the result, I get that it ...
4
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1answer
293 views

Assign order number in which line intersect polygons

Is there any tool (plugin) for QGIS to assign order (sequence) number of line intersecting through polygons? At this moment I use a bit cumbersome solution which works but... I use Qchainage plugin ...
3
votes
1answer
58 views

Intersection tolerance error with Shapely

I am using Shapely to do a basic intersection operation. However, Shapely doesn't return the intersection line I am looking for. I though the reason might be Shapely's intersection doesn't have ArcGIS'...
2
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1answer
57 views

Aggregates Functions - QGIS - Calculating Area Explained

I've been reading through question and answers on the Aggregates Function, but have been unable to obtain a clear understanding and solution to my problem. I have a polygon grid ("Grid 4km") and I ...
27
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3answers
16k views

Ignoring invalid input features with Intersection tool in QGIS?

In QGIS 2.18, when I used the Vector > Geoprocessing Tools > Intersection tool, I was able to check an option which said "Ignore NULL geometries [optional]". Now I've downloaded QGIS 3.2 and that ...
1
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1answer
1k views

Calculating intersect of two shapefiles using QGIS [duplicate]

I have two shapefiles. 1. the clinic buffers 500m area. 2. the postcode area. Is there a simple way to calculate the intersect two shapefiles ? I'm using QGIS Dufour. I tried to use fTools to ...
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0answers
23 views

Setting topology rules to connect short lines aross complex intersections

I have a polyline SHP with a bunch of very short lines (less than one meter length). Is there an automated way to force the short lines to connect to a neighboring line at complex intersections? ...
1
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0answers
22 views

Choosing Clip or Insersect tool in QGIS? [closed]

I am doing a analysis but I have information which is not available in all disagregation levels. I mean, some data is at a national level, other is at subnational level and other is in district level. ...
1
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0answers
17 views

Create grid with a prespecified number of cells inside a shapefile with R

I need to create a grid inside a shapefile with a fixed the number of cells n (inside the shapefile). I tried a few stuff see bellow but nothing worked so far. Any ideas? The data shapefile can be ...
1
vote
1answer
811 views

Intersecting overlapping polygons individually in ArcGIS Desktop

Map Layers: Census Tract ShapeFile with Population Data Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...
3
votes
1answer
341 views

ST_Intersection between MultiPolygon tables leads to gaps, missing intersections

I am trying to intersect two MultiPolygon tables, which are in the same UTM projection, and calculate the area of their intersections. I am getting some surprising results when I examine the ...
3
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0answers
96 views

Find a centerline of an intersection between two irregular shaped polygons

I have two irregular shaped polygons that overlap each other at least in at two points. I want to first find the intersection area between all of them, then for the polygon pair that intersects I want ...
0
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0answers
41 views

Finding out if crossroad or 3-way-intersection

I'm trying to find out the type of a crossroad / intersection in overpass by given coordinates (simple 4-way-crossroad or 3-way-intersection aka Y/T intersection). Wanted to count the way-id's I'm ...
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0answers
27 views

Improve OGR SQL query for polygon intersection using WKT geometry

I want calculate the intersected area between a shapefile and WKT geometry. My target big layer: a.shp My query small layer: 'POLYGON((1150046 1264030, 1160100 1263793, 1160079 1260606, 1150218 ...
0
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1answer
121 views

Overlapping two line problem

I want to check if 2 linestrings intersects (or overlaps) or no. I use turf.js overlap. Here are the results I want to get: CodePen 1- If only first or last points of line 1 intersects with first ...
2
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1answer
35 views

Using Geos C++ Library to return overlap and intersects [closed]

I'm running GEOS C++ Library v 3.6 on Fedora. I have a list of geometries I loaded from a shapefile and converted to geos polygons. The shapefile is large and I may be overlaying several ones to ...
8
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2answers
247 views

Tool that modifies number of vertices but not the feature itself

Do you know the reason, why some ArcGIS tools (like Clip and Intersect) modifies number of vertices, even if the feature is not modified itself? Like on the picture, I use Clip and Intersect on line ...
2
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2answers
4k views

Querying intersecting areas areas - Oracle Locator or Spatial?

My spatial database is Oracle. We are wondering if we can use basic Oracle Locator or need to get the more expensive, full, Oracle Spatial. My application's requirements include having to be able to ...
0
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0answers
59 views

Spatial intersection of features (Oracle Spatial) with a line stored in a local gml file?

Interesting sites are stored as polygon features are stored in an Oracle Spatial read only dB. I have a local GML file containing a line (EPSG:31370 - corresponding to a trajectory over a couple of ...
2
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1answer
44 views

Check if points that share attribute intersect polygons

How to check whether points started in red and ended in a blue polygon (and vice versa) while sharing the same attribute? To check if the first location of the unique ID is in one polygon and last in ...
2
votes
1answer
56 views

Points along lines at set elevation intervals [closed]

I am looking for a way to create points along lines (roads) at set elevation differences (0.5m height differences) using QGIS.
4
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2answers
6k views

How to fix overlapping polygons using ArcGIS for Desktop?

I'm using ArcMap 10.3. I have a layer of different land use types. After calculating the percentage of each land use in the catchment using tabulate intersection, I found out that the percentage of ...