Where features overlap

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2
votes
1answer
237 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
754 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
666 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
606 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
643 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
334 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
81 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
265 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
459 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
400 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
297 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
292 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
895 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 ...
8
votes
2answers
7k 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 ...
3
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
234 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
2k 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
390 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, ...
5
votes
2answers
2k views

Need help calculating forest cover within a buffer when it overlaps with other buffers

I'm new to ArcGIS and having real trouble getting this done… Hopefully someone can help. Thanks in advance! I have a layer showing forest cover in a landscape. I'm trying to create a 5km buffer ...
3
votes
2answers
732 views

How do I find the points of intersection between a small circle and a great circle?

I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle. I found this tutorial for intersecting two great circle arcs, but ...
5
votes
1answer
264 views

Intermediate points on a small circle

I need to interpolate lat/lon points along a small circle, with a given centre and radius. I've successfully used these formulas for great circles. What is the equivalent for small circles?
3
votes
1answer
448 views

ITopologicalOperator.Intersect, how does this work?

I'm trying to intersect all features of a layer with another's but I'm getting the web ADF application stuck while executing the "ConstructUnion" function Here's the code I've written so far // ...
13
votes
6answers
7k views

How to use ST_Intersection?

Here's a quick summary about what I'm trying to do: I have 3 tables in Postgres, 'a' and 'b', each have a Polygon column, and 'c' has a Point column. What I'm trying to do here is to get the ...
4
votes
3answers
210 views

Is the Intersection Operation Commutative?

In map overlay, is intersection of map layers a commutative operation ie layer_A intersection layer_B = layer_B intersection layer_A? If layer A is a square and layer B is a triangle. In this case, (A ...
6
votes
1answer
886 views

Intersection of multiple layers in PostGIS

I need to write PL/pgSQL stored procedure for calculation of intersection of multiple layers. For example, for three layers A, B, C this function should return ABC geometry: Function takes as input ...
5
votes
1answer
349 views

Intersect between Surface and Ray

I am interested in finding the intersection of a Ray and a Surface in ArcObjects. I already know of two solutions. First solution is to use the Locate method of ISurface: Dim intersectionPoint As ...
3
votes
2answers
3k views

Measure the area of a polygon resulting from the intersection of two other polygons?

How can I measure the area of a polygon resulting from the intersection of two other polygons? If I use the measure tool or open the attribute table for the resulting polygon, it shows me the areas of ...
5
votes
1answer
1k views

How do I find the intersections of 2 circles on earths surface?

I have the circles' center in lat & long, as well as the radius in meters. How do I find the circles intersections? Edit: EXAMPLE: Circle 1: Center on Earth's surface (43.564627,-116.220524) ...
5
votes
1answer
2k views

How to get the intersecting polygon of two polygons? (using JSTS intersection)

I want to intersect two polygons within an OpenLayers layer. I found the JSTS library, which should be able to intersect two polygons, and return the new created polygon of the intersection. The ...
8
votes
4answers
2k views

Best way to find the polygons crossed by a line

I'm trying to find all the polygons crossed by a single line (a GPS track). I'm using the OGR library (from python) for computing this, but it's currently a bit 'brute-force' (and slow). For every ...
17
votes
4answers
3k views

PostGIS: Select features that do NOT intersect

This seems to me like such a simple question (and it probably is) yet I cannot seem to find an example that gives me the answer. Using PostGIS, I just want to select points that fall outside of ...
2
votes
1answer
740 views

Search Intersections with ArcGIS Server 10 without using Address Locator

Is there a way to search for intersections on a centerline layer in ArcGIS Server 10 without using an Address Locator? I can send direct queries to the centerline layer for individual road segments. ...
7
votes
7answers
2k views

Intersection algorithm that correctly handles the 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 ...
18
votes
4answers
6k views

Separate polygons based on intersection using PostGIS

I have a PostGIS table of polygons where some intersect with one another. This is what I'm trying to do: For a given polygon selected by id, give me all of the polygons that intersect. Basically, ...