Where features overlap

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5
votes
2answers
3k 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
856 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 :)
1
vote
2answers
2k 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
465 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 ...
5
votes
1answer
392 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 ...
4
votes
2answers
4k 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 ...
-2
votes
1answer
561 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
765 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 ...
3
votes
2answers
1k 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
votes
2answers
314 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
754 views

ArcGIS Intersect using Geometry Service

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 to ...
2
votes
0answers
179 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 ...
4
votes
1answer
1k 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
1k views

Find intersection points of two polyline features

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
519 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
votes
0answers
547 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
210 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
892 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
vote
0answers
255 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 ...
5
votes
1answer
511 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
843 views

Extract all the intersections from a polyline shapefile

I would like to extract all the intersections from a polyline shapefile and print their addresses as text using either ArcDesktop or Quantum GIS, is there a straightforward way to do this? My ...
2
votes
2answers
393 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
465 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 ...
1
vote
1answer
406 views

GDAL: Raster Intersection

I have two raster layers. (A) is state-sized, 30m. (B) is county-sized, 3m. I'd like to get a new raster (C) which is the part of (A) which coincides with (B), preferably scaled to the same ...
3
votes
1answer
211 views

Intersect multilinestring (A) with multilinestring (B) retaining linear sequencing in resultset? [closed]

I have a PostGIS table testtin2 which is a sort of pseudo TIN consisting of a single multilinestring geometry, which I am intersecting with another table align, also a multilinestring, to generate a ...
2
votes
1answer
228 views

Query for segments at same place and time in PostGIS

A newbie-question: I've imported the segments of several GPX-Tracks in a PostGIS-Table. Now I'm looking for a query that returns all segments that: are spatially overlapping (within a specific ...
2
votes
1answer
715 views

Batch intersect from a text file using Python (ArcGIS)

I am attempting to modify my code below which reads from a text file of shapefiles and executes an intersect and outputs them to a user specified location: import arcpy, sys, os from arcpy import env ...
4
votes
2answers
626 views

is there a way to tell if two linestrings “really” intersect in JTS or GEOS

In JTS (or GEOS) you can't tell if two linestrings really cross each other. The result is exactly the same whether the lines simply have a point in common but don't cross or if they really cross. Is ...
4
votes
1answer
587 views

Spatial Join in PostGIS according to Line Attribute

I am in the process of building a data warehouse in PostGIS, that will store the length of the road network of a country (Lines) per Administrative Area (i.e. Province or State, referred to as AA ...
0
votes
1answer
622 views

Testing if shapefiles intersect from a list using intersect: ArcGIS

I am new to programming and scripting in general, so please bear with me. I have generated a list of the location of all the shapefiles for my workplace. The files are all placed in folders, no ...
4
votes
1answer
325 views

Finding intersection density for weighted lines connecting points across the continental USA

I'm working on an one-time problem that I'm hoping to solve with a computer program using free GIS libraries (preferably for VB.Net, C#, or Python... Java or C/C++ could work too). Alternatively, I ...
2
votes
2answers
79 views

What is an extension error?

I am getting an extension error when I try and intersect some points and polygons. Here is a photo of what I am trying to intersect: Any help is appreciated.
4
votes
1answer
1k views

PostGIS geometry intersection test results different for Point and Linestring

Can anyone please tell me what I'm doing wrong, and how do I avoid the problem? I'll attempt to clarify what I'm doing as things go along. The geom column is a multipolygon column, all values are ...
8
votes
4answers
3k 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: ...
3
votes
0answers
261 views

How to get all intersections between two simple polygons in O(n+k)? [closed]

Can someone help with a following problem: report all intersections between two simple polygons in O(n+k) where n - is a total number of polygon edges and k - is number of intersections. As a result - ...
3
votes
1answer
446 views

Is there a commandline tool for intersecting Shapefiles?

in QGIS vectorlayers can be intersected. That is apparently done by ftools and seems to be integrated into the QGIS-program itself. That is different from many other functions that call GDAL-tools. ...
3
votes
1answer
385 views

ArcObjects 9.2 SDK: How to intersect two SelectionSets (in-memory pointers) and return a FeatureClass?

[Update] Since posting this question, I've come to the conclusion I'm not fighting flaws in the BasicGeoprocessor object, but more likely having issues with poor object lifecycle management on my ...
0
votes
1answer
292 views

Generate a report or table for buffer zone

I have a polygon feature class. I create a buffer for this feature with a distance being 2 km.Now the buffer output intersect with features of the original polygon.So say for instance from the orginal ...
14
votes
2answers
3k 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
1answer
290 views

ArcMap: extracting overlapped buffers

I have a set of points in ArcMap which I create a buffer for each point. Then I use intersect to extract the overlapping buffers. The result is something like this: The lighter color are the ...
1
vote
0answers
104 views

Copied points not intersecting the original points

I'm using an arcpy search cursor to access a Oracle database. I have a simple Python class that I copy the returned row objects into, which gives me more flexiblity than the cursor. The problem is ...
4
votes
1answer
4k views

Create point in intersections of two layers

I have two layers. One of them is 'Road_line' and another one is 'forest_shape'. I want to create a point layer that has points in intersection of that layers. I couldn't find any tools for it. Could ...
3
votes
2answers
857 views

Selecting points not snapped

I have a point layer and a polyline layer. I want to select all points in the point layer that are not snapped to a vertex in the polyline layer. How can I accomplish this? I'm using MapInfo and ...
6
votes
2answers
6k 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 ...
2
votes
1answer
100 views

Can I take an intersection for polygons WITH A COMMON ID?

I have a thiessan polygons for a bunch of cell towers, and need to cut them when they extend more than 12 miles from a cell tower. What I was thinking of doing is taking a buffer from each point, and ...
6
votes
1answer
4k views

can I extract overlap of polygons within the same layer?

I am trying to extract the overlap of polygons that are within the same layer in 10. The layer came from a buffered street centerline and I'm trying to extract and delete the intersections from the ...
2
votes
2answers
2k views

How to query which features of all vector layers intersect with a given bounds?

I am writing a Openlayers map app, and wondering whether there's a better practice to query which features of which vector layers intersect with a given bounds.. It's certainly not a good idea to ...
1
vote
1answer
233 views

How to get all intersecting points to a given area and vice-versa in PostGIS?

I'm developing a project using PostGIS to hold spatial data where I have records that hold geometry point data and records that hold geometry area data. To solve my problem I'm looking for two queries ...
3
votes
1answer
1k views

Intersect two polylines using ArcObjects

I have two polylines and would like to find the intersection(s) using ArcObjects / VB.NET. I'm using the following code: Dim topoOp As ITopologicalOperator = TryCast(pTestPoly2, ...
4
votes
1answer
376 views

automating forest cover calculations with Python

I have a layer of forest cover comprising ~ 30,000 individual forest patches, and I need to calculate the amount of forest cover within a 5 km buffer of each patch. The buffers all overlap each other, ...