Where features overlap

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1answer
106 views

determining what polygons intersect another layer

I am attempting to establish what spatial relationship exists (if any) between two layers. I have two layers - one is a road network with a buffer of 500m, and the other is a collection of polygons ...
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2answers
278 views

unionize intersections of merged polygons

[Updated quesion] I am using the following code to merged polygons from shapefiles for the purpose of calculating the surface area; library(maptools) library(rgdal) library(rgeos) #enter slots, ...
2
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1answer
244 views

Creating buffers that will not overlap in QGIS

I am dealing with a .shp with a number of points in it. The distances between points range from ~300m to 5km. I wish to create a 1 km buffer around each point with as little overlap as possible. Each ...
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3answers
270 views

Produce a list of polygons that a line crosses

I have a polyline feature class and a polygon feature class. What I want to do is add a field to the lines that lists all polygons that touch the line. This is effectively performing a ...
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1answer
65 views

Mismatch in area calculation using Field Calculator vs Group Stats in QGIS 2.0

I have two polygon files (A being my area of interest and B being a categorised land cover layer). Both layers were in the same projection (projected and not geographic). Using QGIS 2.0, I used the ...
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1answer
86 views

Separating distinct lines in PostGIS

I have a table of linestring segments in Postgis. These segments make up distinct non-intersecting lines as shown by the diagram. To add confusion the direction of the linestrings are not uniform. I ...
2
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2answers
130 views

How to check if vertex exists (on polyline) based on location of point layer using ArcPy?

Using ArcGIS for Desktop Advanced 10.1 (with all extensions) I am building a centerline network that will be used by a MapObjects program to do routing based on "turns at any vertex" (as opposed to ...
0
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1answer
260 views

Maximum size on the bounding box with ST_MakeEnvelope and && and geography column in PostGIS?

I've done quite a few google searches, but haven't managed to find anything that has helped me directly. I've got a few features in a PostGIS table with a geography column. The features are focused ...
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2answers
145 views

Is there a way to speed up gIntersections for large spatial objects?

I'm attempting to perform a gIntersection of a big grid on a shapefile for country boundaries, so that I can calculate the % area of each grid cell that lies within the country. It takes a few seconds ...
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0answers
22 views

Program crashes when trying to do intersection.

I'm trying to get the intersection between a highways shapefile and some states in Mexico but it seems that the program always crashes. I attach the images of what I'm trying to do and the error that ...
0
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1answer
190 views

Intersecting polygons in Oracle

Have a polygon in table 2 with its id, no and geometry. In table 1 I have polygons with the same fields. The polygon in table in intersects with a few polygons from table 1.What I am trying to do is ...
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2answers
163 views

Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
2
votes
1answer
467 views

PostGIS: Calculate the length of just the portion of linestring that intersect with a polygon

I want to calculate the portion of the linestring that lies within the limits of a polygon. Better with an image What is the length of the portion of linestring within Province A? and within ...
4
votes
1answer
471 views

How to use the Intersects function in the Field Calculator of QGIS?

I would like to have an example on how to use the Intersects function in the Field Calculator of QGIS. Basically, I want to know which feature from a polylines layer intersects a polygons layer and ...
2
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3answers
1k views

Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
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3answers
240 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 ...
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1answer
105 views

Load Raster Values into Shapefile [duplicate]

I have a shapefile containing many points. Some of these points fall within an area for which I have raster data. I would like to load the values of the raster which underlie each point into the ...
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2answers
187 views

geospatial libraries like postgis

I'm pretty comfortable with postgis, but I realized that for part of my application, having a database is pretty heavy. I'd like to be able to take a stream of Point objects and check against an in ...
6
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1answer
381 views

Performance in calculating raster statistics in PostGIS

I'm trying to calculate raster statistics (min, max, mean) for each polygon in a vector layer using PostgreSQL/PostGIS. This GIS.SE answer describes how to do this, by calculating the intersection ...
1
vote
1answer
190 views

How to calculate the intersect two shapefiles [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 ...
1
vote
1answer
92 views

How to perform intersect operations in the Field Calculator in QGIS?

How to use the Intersect function? How would I specify to REPLACE layer1.field1 with layer2.field2 WHEN layer1.geometry INTERSECTS layer2.geometry Is that feasible in QGIS?
2
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0answers
72 views

How to copy the contents of an attribute from one vector layer to another one that touches it or intersects it?

I have 2 layers that intersect, called layer A and layer B. Layer A has an attribute (X) that I want to copy wholesale (for the whole layer) to layer B, so that when object A1 intersects object B1, ...
3
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1answer
154 views

intersection between two multipolygons yielding anomalous GeometryCollection object full of LineString's & Polygon's (trying to get intersect area)

Normally when I call the #intersection method on a multipolygon to find the intersection shape on another multipolygon I get a multipolygon returned back to me. Either that or something else I can ...
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0answers
101 views

Line - Line and Line - Polygon intersection in WGS84

What is the correct way (which formula, what algorithm, etc) to determine the intersection point of two lines specified in Lat/Lon coordinates on a WGS84 model? Note that the lines might be very long ...
1
vote
1answer
268 views

Intersection of multi-polygons in postgis

How can I get the intersection of 3 multi-polygons in postgis? I have three geometry collection and I want a fourth with the result of intersection of the other three. ...
2
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2answers
2k views

How to delete overlapping polygon features from one of two layers?

I really need your help! I have two overlapping layers of polygons, and i need to somehow erase the areas the overlaps. -This way i should end up with two layers of non overlapping polygons. Sounds ...
5
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1answer
732 views

Split polylines at polygon boundaries in QGIS

I have a set of contour lines and a polygon set containing glaciers. Because I want the glaciers to have blue contours, I need to split the contour lines at the glacier boundaries. I can achieve this ...
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2answers
83 views

Using st_intersects caused mismatch when a marking (tagging) shape marked a polygon overlapping only on the edge

I have accidentally marked a landshape as being tagged "CU GO-M" because it seems to share an edge with a tagshape for "CU GO-M" but nothing else. I used the st_intersects method to join these shapes ...
0
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2answers
193 views

Intersection between points and polygons in QGis

I have the following problem. I have a shapefile of points and a shapefile of polygons. I want to know WHAT points (not how many) fall inside EACH of the polygons of my multipolygon shp. I thought ...
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0answers
188 views

Creating a BATCH with multiple INPUTS (variables) to run a workbench that intersects LINES AND POLYGONS

I'm trying to create a batch file to run my workbench.fmw in which I have two input files: 8 pipeline shapefiles and 96 communal areas shapefiles. The workbench allows cutting pipeline relative to the ...
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2answers
170 views

Integrate grid and polygon of municipalities keeping the biggest municipality per cell with QGIS (or another)

I have a 9x9 grid and a polygon of municipalities of an extensive area of Brazil. My goal is to have a field indicating the biggest municipality per grid cell. I've been trying with intercept without ...
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0answers
50 views

Broadband coverage GIF image layer needs to be selectable (ArcGIS)

I am working on a project on Arcmap where I have 80,000 co-ordinates of postcodes and a broadband coverage map. I need to know which of the co-ordinates intersect with the coverage map. I have added ...
4
votes
1answer
670 views

Obtain voronoi polygons which extend till the boundary of another polygon

I have certain hubs (coloured yellow) in a district (coloured light blue). I need to find polygons indicating the closest hub to every point in the district. The voronoi polygons that I obtained ...
0
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1answer
51 views

Is it possible to draw a point interactively and execute an intersection operation (drill down) to identify spatial relationship with other layers?

Is it possible to draw a point interactively and execute an intersection operation (drill down) to identify spatial relationship with other layers using GeoServer? I am a newbie with GeoServer…
2
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1answer
48 views

Need to put points on overlapping boundaries

I have two layers: a route (Line) and a county boundary (polygon). I need to intersect them so that the output layer is a point layer. The ArcGIS Intersect tool places a point where the route passes ...
1
vote
3answers
122 views

PostGIS intersect on insert?

I have a large amount of point data that I have in CSV form. I am able to insert it all into a PostGIS table no problem. What I want to do though, is split the data up on insert into multiple separate ...
0
votes
2answers
551 views

Detecting invalid polygons (self-intersecting or touching)

An invalid polygon can be defined as one that intersects itself, or one where the lines make contact, ie, the two shapes at the top of this picture. Given the XYPoints of a polygon, what logic ...
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0answers
73 views

Vector/Raster Intersection - Speedup and replacement for ST_Centroid

I have some raster data which is the altitude above sea level and also some vector data which represents building outlines. What I want to do is grab some buildings outlines and fetch all the raster ...
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0answers
98 views

how to avoid Intersection of polygons via python code

i am using QGIS 1.8 and i can set the check box in Setting\Snapping Options "Snapping and Digitizing " dialog to avoid polygon intersections and enable topological editing but i am looking for a way ...
1
vote
1answer
65 views

st_intersects on postgis

I'm trying to write a command to see whether a given point lies within a multipolygon boundary (in this case, a watershed). I have a table of watershed boundaries and another table with the point I'm ...
2
votes
2answers
104 views

How to hand over polygon attribute to new point while digitizing?

My task is to work with bird observation data in an area, that is divided into zones as different polygons (A1, A2, etc.). I have the hand-written lists of observations and want to bring all entries ...
2
votes
1answer
69 views

Intersecting Layers Returns Empty Collection Despite Visible Intersection

When I perform an intersection of a polygon I draw in OpenLayers and a postgis database layer, it seems that I am getting incorrect results. Intersection works correctly on some layers. For ...
4
votes
1answer
481 views

How to split a polygon using R

I have an irregular polygon which is a spatial object. I want to divide it into multiple polygons (say, n=25) with equal height. To show how I want to divide it, I've plotted grids on the ...
5
votes
1answer
122 views

Simulating Random Agent Movements along Roads on Map

I need to simulate agent movements on map as follows: Agent starts a known location and moves along a road. At each road intersection, the agent uniformly chooses one possible road and moves along ...
2
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0answers
223 views

3D features (Polyline, Polygon) intersection library

For my research I am looking for a (python) library to get the intersection of some 3D features. The features can be Polygons or Polylines. Mostly I need to intersect a plane with my features and get ...
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2answers
321 views

Retrieve common paths of polylines ArcObjects

I have a polygon featureClass and a polyline featureClass. I now want to handle all geometries within the latter that are contained in the boundaries of polygon features, that means they shell simply ...
1
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1answer
679 views

How to find the intersection point of polygon geometry and multilinestring geometry in postgis

I have a polygon geometry and multilinestring geometry. How do i find the intersection of both these geometries. Both the geometries are in same reference system. Does st_intersection gives me the ...
1
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2answers
3k views

QGis: Merge intersecting polygons into one which are part of the same feature

I'm not a GIS professional so I hope I use the correct wording, at least I hope you understand my question. Let's say there are 5 polygons in the feature A. In the shape file there are more ...
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0answers
17 views

Finding the exact coordinates of circle's extreme east and west points on a sphere [duplicate]

I'm currently implementing the Bentley-Ottman algorithm applied to spheres, involving intersections of many spheres on one sphere, circles in most cases of course. This requires locating "event" ...
0
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1answer
276 views

Polygon color on intersect

Using OpenLayers, I am loading a large geojason file of about 4000 polygons. Once the polygons are loaded I want to draw a "LineString" on the map (already done and working). My challenge is that I ...