Where features overlap

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0
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1answer
223 views

Rhumb lines intersection

I looking for algorithm how to find out whether two rhumb lines given by point1 with azimuth1 and point2 with azimuth2 have intersecting point. Have anyone idea how to find intersection ? For ...
1
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1answer
406 views

openlayers point intersection

For example, I have 2 points and I want to know if they intersect. If yes, I need to delete first points. Should I use OpenLayers .intersects method? Because it greatly depends on zoom level. Or ...
3
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4answers
1k views

ArcObjects C#: select intersecting polylines

My questions seems trivial but it is a real blocker for me. So please help!!! How can I, using ArcObjects with C#, select only those polylines in one layer that intersect with each other? It sounds ...
1
vote
0answers
431 views

intersect two shape files using QGIS API

I am trying to automate a process of a shape file. We are using google maps engine and we have limitation on number vertices in a shape file. so I am using a grid to split the shape files. In GUI , I ...
3
votes
2answers
698 views

Postgis: aggregate function for intersection

I have a PostGIS Table with LINESTRINGS. I like to a query that returns all Roads that are connected. So I get a set of unconnected trees (in german 'Wald (Graphentheorie)') pseudo code: select ...
2
votes
1answer
724 views

How to use QgsOverlayAnalyzer class in pyQGIS?

I am very new to Python scripting in QuantumGIS, so bear with me please. I am trying to use the QgsOverlayAnalyzer class in QuantumGIS (http://www.qgis.org/api/classQgsOverlayAnalyzer.html#details) ...
1
vote
1answer
1k views

Lat Long line intersecting with circle

Can anyone help me what's the algorythm to calculate points of intersection whet is given one point p1 [lat,long] , bearing x (let say 137 degrees), arc center [lat,long] and radius? I woulde like to ...
2
votes
1answer
768 views

Remove intersect of one polygon from another in R

I am trying to remove the intersect from Poly2 onto Poly1. Below are the coords of the 2 polygons. > coords1 [,1] [,2] [1,] 992.0161 7462.531 [2,] 950.1962 7413.532 [3,] 902.3632 ...
2
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1answer
704 views

Intersection of convex polygons on a spherical surface

There are a number of algorithms available for the intersection of two convex polygons, but I am interested in an algorithm to find the intersection of two convex polygons on the surface of a sphere, ...
1
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0answers
33 views

Suggestions for vector format for polygons

I am using two polygon tables in postgis (A and B ). I need to make a vector file that incorporates information of the overlapped polygons B intersecting each polygon on (A). I can make a single ...
2
votes
2answers
190 views

Showing OpenStreetMap intersections in ArcMap?

I'm trying to carry out a few tests on OpenStreetMap data to test its quality, using ArcGIS. One of the things I'd like to investigate involves checking that all road intersections are represented ...
3
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1answer
624 views

Intersection of drawn polygon with WMS layer features. Better of two methods?

Scenario: Several WMS layers with polygon features. Objective: Draw a polygon with OpenLayers and allow it only if doesn't not cut any features in WMS layer. It can contain the features as a whole ...
3
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1answer
410 views

PostGIS: Using a polygon to 'mask' linestrings returns both multi and linestrings

I have a table of linestrings (OSM roads, in fact) that I'm displaying on a map. I want to filter them so that only those within a certain area are displayed- I've already done this with the coastline ...
1
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0answers
494 views

How to handle/ avoid intersect errors when clipping the difference between two layers?

Using QGIS + Grass, I've added a shapefile of coastline and islands to my map. I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
1
vote
1answer
489 views

Why do I get 'KeyError: 0' when using Line Intersection tool?

I'm using Quantum GIS version 1.8.0-Lisboa and trying to create intersection point using Intersection tool. (Vector -> Analysis tools -> Line Intersections ) But when I do that for my shapefile, It ...
4
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2answers
136 views

Creating space at intersection of two links

I have a shapefile consisting of two links which are crossing over each other. I want to create an empty space at the point of intersection of the two links. As of now, I have been manually doing ...
3
votes
1answer
164 views

Help with intersections in QGIS

I have a shapefile which defines for me the area of each oil field in the North Sea (~300 fields). I also have a shapefile which defines the location of every well that has been drilled (~13000) ...
7
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3answers
5k views

Extract Overlapping Polygon Data to Points

I have a polygon data set of corn yield collected by a combine. However, as the combine drove through the field, there was slight overlap between passes, leading to overlapping polygons within the ...
5
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3answers
571 views

Trying to combine nearby points into a polygon

We have collected millions of cell phone strength readings. I am trying to group points of the same strenght that are within a distance of each other in to a polygon. I asked on the postgis mailing ...
4
votes
2answers
2k views

How to Intersect between a vector (administrative areas) and a raster layer (slope)?

What I've got: 1: A vector-layer with administrative areas of my country 2: A raster-layer with the slope of the terrain of the same country (it is derived from SRTM elevation data with QGIS) What ...
1
vote
1answer
984 views

Intersection between two SpatialPolygonsDataFrame using gIntersection function in R

I want to select a subset of my map (a SpatialPolygonsDataFrame) to create a new vector map = part of the initial map included inside a given polygon (eventually, inside several polygons). I have a ...
4
votes
2answers
3k views

OpenLayers - Get features inside a polygon

In my OpenLayers map I allow users to draw an ad-hoc polygon vector. Then I need to get all the features from a WFS vector layer that fall within the ad-hoc polygon. Here is the code I have that ...
3
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4answers
2k views

How can all polylines within a polygon be selected and then operated on to determine the average value from an attribute field?

I have two files illustrated wonderfully below: 1) Polyline (shown in red), 2) Polygon (shown in black). The polyline file contains a numeric attribute (elevation in meters). I would like to select ...
2
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1answer
173 views

Line feature, Merge and Dissolve

I have a layer with several polygons and a layer with line above these polygons. Its like a map and a road network on it. I have to find out the length of line in each polygon. I used the intersect ...
5
votes
1answer
631 views

adding multiple points to a linestring in PostGIS

Though a newbie to PostGIS, I'm having trouble solving something that I think should be farily straightforward. I have two linestring tables, both consisting of simple, 2-node line objects: one has ...
4
votes
2answers
602 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 ...
4
votes
2answers
934 views

How to select features that intersect but don't touch (using ArcObjects)?

So how do I do that? ArcMap's Select By Location selects also all features that touch, but I only need the ones that actually intersect the area. I currently use ...
8
votes
2answers
7k views

Calculate area of intersecting polygons in QGIS

I have two collections of shapefiles: 1 - postal codes, administrative and political areas 2 - various land use categories like parks & allotments, and points like trees I want to produce ...
4
votes
1answer
1k 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
2answers
3k 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 ...
2
votes
2answers
654 views

How to single out country data from a world data map?

Say that i have two "data sources"; A global map of average wind speeds, A shape file (or similar information) of all country borders in the world. How do i combine these two sources and extract ...
7
votes
2answers
1k 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 ...
6
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2answers
8k 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 ...
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1answer
1k 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( ...
0
votes
3answers
1k views

Trying to fetch feature data by intersecting Vector Polygon and WMS feature layer

I am trying to intersect a user defined polygon with a Point WMS Feature Layer. I am using the following code action = new GeoExt.Action({ text: "draw poly", control: new ...
5
votes
2answers
2k views

Is there a way to get at C's OGRLayer.Intersection() or OGRLayer.Clip() in Python?

I am working with OGR in Python and noticed that the C libraries have useful Intersection() and Clip() functions as part of the Layer class. Is there any way to get at these functions in Python? I ...
4
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2answers
423 views

No intersection found between polygons I know intersect!

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. ...
5
votes
1answer
1k views

ArcGIS Intersect using Geometry Service [closed]

I am using the intersect service from the ArcGIS Geometry service. referring : http://help.arcgis.com/en/webapi/sil....htm#Intersect I have modified it to make it work with polylines it works fine ...
2
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0answers
214 views

How could I make this PostGIS query run faster?

SELECT st_band(rast, 1), st_width(rast), st_height(rast), st_bandpixeltype(rast, 1), st_bandnodatavalue(rast, 1), st_scalex(rast), st_scaley(rast), st_upperleftx(rast), st_upperlefty(rast) FROM ...
5
votes
1answer
2k views

How to find all intersections and count lines arriving at each intersection?

I'm having a hard time getting off the ground with this, and am trying to move away from ArcGIS / arcpy. I have a shapefile with a network of polylines. I want to find/count all 2-way intersections, ...
3
votes
2answers
2k views

Finding intersection points of two polyline features using ArcObjects?

I'm currently working with street intersections trying to find point(or points) where 2 given streets intersect(!disjoin). Streets are all Polyline features, and I have to work with 2 features at ...
3
votes
1answer
742 views

select polyline intersections from one shapefile using QGIS

I'd like to find out if there is a way to select all of the polyline intersections within one shapefile. The lines are a road network. I've looked through the posts, and the only tip I can find is the ...
2
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0answers
648 views

cant find point/polygon intersect using qgis (windows only)

below i describe the method i am using. i have 2 machines: 1 ubuntu linux, qgis 1.4 - intersection works 2 WIN xp, qgis 1.8 - intersection dows not work hopefully, someone will ...
1
vote
1answer
246 views

How to identify Polygon within another Polygon layer

I have two polygons files. The first one has several smaller polygons within it eg.a shapefile with all US states, the other polygon file has a single polygon eg. a river basin. I am trying to get all ...
1
vote
1answer
1k views

GetFeature Request with Polygon Intersecting Polygons

My task is very straightforward: a user draws a polygon and query all parcel polygons. The query string extends the URL limit. So I am posting XML to WFS. However, GeoServer always returned 0 feature, ...
1
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0answers
283 views

error in gp.execute intersect

i generate a tool to return values using area of polygons. but when i execute the tool, visual studio show an error :"Error HRESULT E_FAIL has been returned from a call to a COM component" in ...
6
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1answer
647 views

Apportioning Points at a street intersection (arcgis or mapinfo)

I can't seem to find any evidence of this question, but I'm surprised by that, so pardon if this has been asked. If one is mapping crime location reports, by XY coordinates to streets, to create ...
2
votes
1answer
1k views

Extracting all intersections from polyline shapefile using QGIS?

I would like to extract all the intersections from a polyline shapefile and print their addresses as text using QGIS. Is there a straightforward way to do this? My polyline has address ...
2
votes
2answers
473 views

count features in polygon shapefile A that fall within each feature of polygon shapefile B

I have two polygon shapefiles, each of which contain multiple (possibly overlapping) polygons. Is there some way, using GRASS, to calculate the number of polygons belonging to shapefile A that fall ...
5
votes
2answers
606 views

Best strategy for polygon search?

I have a fairly simple question. What is the best strategy to do the following scenario? I think this is a very common scenario: I have a several thousands of dataset with polygon/points. Each ...