# Questions tagged [intersection]

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

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### Finding percentage of intersection in polygon

For two given polygons generated in this code, how do I find the percentage of intersection on the rectangle? [The polygon was created using the Alphashape function] (Linked to Finding points of ...
15 views

### Finding points of intersection in polygon?

For two given polygons generated as shown below, how do I find the points that are intersected on the rectangle by the circle? [The polygon was created using the Alphashape function] (Similar to ...
112 views

### Query Z at intersecting point locations from a MultiPolygonZ?

I create a MultiPolygonZ geometry with ST_DelaunayTriangles(). select st_setsrid( ST_CollectionExtract( ST_DelaunayTriangles( ST_GeomFromText('MULTIPOINT ...
104 views

### Trimming road end at the intersection?

I have a road centerline that I have used to create buffers that represent road area. Now I need to fix the intersections. As you can see on the picture, if the road end is touching the non-end of the ...
105 views

### Variable Buffer on Street Centerline using ArcGIS

I have a street centerline file where all road segments have a functional class of Arterial (A), Collector (C), Local (L). I also have a point file of each intersection. I would like to do a crash ...
226 views

### Seeking solution for PostGIS raster 3d intersection?

Is there a PostGIS solution to a 3D intersection between a DEM raster (with elevation in band 1) and a 3D line? Here are some facts: Rasters only support 2D processing so I can't use ...
174 views

### Length of intersections from a linestring and a grid shapefile by using Python GeoPandas & QGIS

I am using Python GeoPandas and I have two shapefiles. One of them is a grid file containing equal polygons. The other shapefile is a linestring file with several lines and its Attributes. The idea ...
64 views

### Replicating“Intersection” function in QGIS using PostGIS queries

I have two multipolygon shapefiles that I've imported into my PostGIS database - one of congressional districts (cds) and one of US counties (ctys). Below shows the counties in blue and the districts ...
209 views

### Defining partial or complete overlap with QgsSpatialIndex

I'm working on adding some functionality to a QGIS plugin. It currently uses a QgsSpatialIndex to efficiently compute whether the features of a vector layer intersect (potentially millions) of ...
35 views

### Stop SQL Server selecting outside buffer

I am trying to select all the parks within 200m or a railway. I can easily create and visualise the 200m buffer. However when i try and find only the parks that intersect it i get all parks returned,...
36 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 ...
45 views

### Determining if Raster and Polygon intersect using ArcPy?

I have a folder of rasters (.tif) and I want to determine which rasters intersect a polygon. The rasters are single band with a value of "1" while the rest of the extent has a no data value (coloured ...
37 views

### Building query with st_shared in QGIS

I have a table with county polygon boundaries (named "counties"). I need to build a query that identifies a particular county as well as any adjoining counties that share the same border. Have tried ...
7k views

### Intersection algorithm that correctly handles 180° meridian and poles?

Is there a well known intersection algorithm that correctly handles 180 meridian and poles? For example, let's say we have a list of latitude and longitude values that represent Antarctica. Let's ...
32 views

### How to delete vertex and keep topology

I work with line vector data (road network).The lines (roads) includes several vertexes. I would like to have for each line only nodes - at the end of line, or at the intersection of n lines. How can ...
51 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 ...
137 views

### Summing number of intersections with separate buffer layer using QGIS?

I have two layers: 1) census blocks, and 2) point data. My goal is to calculate the sum of the point data within the census blocks to eventually create a choropleth map and to run regression models ...
10k views

### OGR Layer Intersection

I am using what I would describe as the most primitive method of doing intersection with OGR. The short script below describes how I do it. Is there a best way of doing this? from osgeo import ...
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### Split height data based upon grid? (Same as Create Grid, Intersection, Split Data for Vector)

I have vector data for a large area that I have split into 2km x 2km layers using Create Grid, Intersection, and split, within the vector menu. I've downloaded STRM data for the whole area. I'd like ...
24 views

### Faster calculation of Shapely polygon-line intersection

I am running a Python Shapely where I have a rotating and translating polygon for which I obtain some probe signals in the following way: for theta_index, theta in enumerate(thetas): rotated = ...
148 views

### Determining if Point is in Polygon using PostGIS?

I want to check if a point is inside a fenced polygon. INSERT INTO polygon (name, geom) VALUES ('test', ST_GeomFromGeoJSON('{"type": "Polygon", "coordinates": [[0,0], [0,5], [5, 5], [5,0]]}')); ...
255 views

### Getting Unique Intersections of Multiple Polygons Efficiently in Python

I would like to get a list of all polygons that are intersections of other polygons. However, that list of intersections cannot self-overlap. For example, if I have a triple Venn diagram, I would ...
33 views

### How to get the intersected region(s) of multiple polygon layers

I have multiple layers with polygons. I want the regions that are intersected by all the polygons. The shared, common regions. An example use case would be finding the shared area of multiple raster ...
278 views

### Using Geometry commands in MS SQL Server 2008?

I am looking to find the most effect way to use SDE and ST_Geometry SQL commands. Can anyone tell me how/what commands I might use to perform a spatial query in MS Sql Server 2008, to Select ...
24 views

### Unioning a set of intersections [closed]

I'm working with two datasets: a set of precincts and a set of census block groups. The census block groups include water; the precincts don't. I would like to trim the census block groups to get only ...
50 views

### Multipart geometry after pyqgis-3 intersection()

I'm trying to intersect two polygons with intersection() function of QgsGeometry (pyqgis-3). The problem is that the result is a multipart polygon instead a single part polygon and QGIS doesn't allow ...
128 views

### QGIS Intersection tool not allowing Save file as Shapefile

In QGIS 2.16.2 I am trying to intersect two Shapefiles to create a third Shapefile, however the Intersection tool is only allowing Save file as DBR, CSV, XLSX or ODS - not SHP. One of the Shapefiles ...
40k views

### 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 ...
10k views

### How to get intersection point from two lines (two coordinated points and two bearings)

I have tried for ages to find the algorithm for getting the coordinate of two intersecting lines from two given coordinated (latitude and longitude) points. As the picture below suggests, I have two ...
84 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 ...
34 views

### Getting area covered by intersection or junction?

I need a way to get following information for each intersection or junction in Berlin: latitude and longitude area covered I could get all Junctions from openstreetmap as nodes, which would give me ...
17 views

### Selecting street segments (polylines) based on intersections with others and adding value to its field from Excel table?

I have a shapefile of city streets polylines and an excel sheet with similar data. I need to select a street segment based on the two segments it intersects. Then I add the value from the "ID" field ...
46 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 ...
51 views

### Identify intersections and assign them to one of the features in a single layer

I have a single SHP-layer (12,810 features) and want first of all to identify intersections (incl. duplicates --> features with identical geometries). In the next step I want to delete/clip these ...
41 views

### Select shapes in one layer that overlap with shapes from another layer?

This question is a duplicate of this: How to select only polygons that overlap with another layer? But in my question I want to know how to do this in QGIS not in ArcGIS. I want to be able to select ...
40 views

### Generating map with polygon aggregation in PostGIS

Generate the map of federal units from the municipalities map in PostgreSQL with PostGIS. Example below: The table has only the geometry information and the "id". I tried: SELECT st_union(m.geom) ...
14 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) ...
44k views

### Finding if two polygons Intersect in Python?

I'm looking for an algorithm, a high level solution, or even a library which can help me determine if two polygons intersect, in Python. I have the vertices of the two polygons (These are single part ...
42k views

### Cropping basemap to specific area using ArcGIS Desktop?

I have a base map from ONS of the entire UK and on another layer I have a boundary outline for the smaller area which I want to crop the base map to. How do I delete everything outside of this small ...
28 views

### Get just not null values from intersection of shapefile and buffer with Python

I generated a buffer using this question: Creating buffer circle x kilometers from point using Python? I did an intersection with this buffer and a shapefile using: intersection_origem = shp_geom....
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### How to get only Intersected polygon in Open Layers 3

I am trying to draw a line on polygon which I want to split, Example: I want to split 616 polygon as show in image with below code when I tied to get intersected polygon I am getting 616,617,615 ...
32 views

### Select polygons which do not contain points

I am able to use the intersect tool to find polygons which overlap with points however I would like to find polygons which do not overlap with any points. I think the Symmetrical Difference Tool ...
65 views

### ArcGIS Intersect Tool not splitting lines as expected?

I performed Intersect Analysis on one polygon shapefile and one polyline shapefile. I didn't specify any tolerances, and both SHPs were projected into the same UTM before performing the analysis. ...
71 views

### GeoPandas intersect not working as expected

Using GeoPandas 0.4.0 with Python 3.5, I'm finding that geopandas.intersects does not behave as I expect it to. For example, a buffer around Switzerland does not appear to intersect with neighbouring ...
182 views

### Intersect multiple layers at once QGIS

I'm very new to QGIS and am just learning the intersect function. I have about 10 polygons that overlap (not perfectly) and one layer of about say 15 points. I want to know with which of the polygons ...
185 views

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### delete pixels intersecting vector border

I have a two files : vector file : polygon (red) raster file : got by clipping a raster file using this vector file (Green) I want to delete pixels that intersect with the vector border (I want to ...
1k views

### ST_Intersection point of two 3D linestrings - how is the Z value calculated?

I have two 3D linestrings (geometry type LINESTRING Z) in a PostGIS database that intersect in 2D space, but not in 3D space. Given that there is technically no 'shared portion' of geometry in 3D, how ...