Where features overlap

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4
votes
1answer
811 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
votes
1answer
55 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
votes
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
126 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
638 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 ...
0
votes
0answers
78 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 ...
1
vote
0answers
101 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
71 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
112 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
70 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
545 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
131 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
votes
0answers
245 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 ...
-1
votes
2answers
380 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
vote
1answer
801 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 ...
2
votes
3answers
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 ...
1
vote
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
votes
1answer
298 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 ...
1
vote
1answer
189 views

Intersect line (LLH) with any LLH plane

I have a LLH (Longitude, Latitude, Height) point with an elevation angle and azimuth (actually it is a receiver point). I believe I can make a line with this information. What I want is to intersect ...
1
vote
0answers
96 views

Gdal/Ogr - OGRLayer.Intersection() Question

I was trying to perform intersection on two feature classes (shape file format) using OGRLayer.Intersection(), but have problems making it work with C# bindings. I am not able to figure out on how to ...
4
votes
1answer
253 views

Clip polygon and retain data

I have these two polygons: library(sp); library(rgeos); library(maptools) coords1 <- matrix(c(-1.841960, -1.823464, -1.838623, -1.841960, 55.663696, 55.659178, 55.650841, ...
2
votes
2answers
920 views

How to determine intersection between geojson feature and given coordinates?

I'm overlaying a leaflet map with features of geojson, fetched with d3 and added as SVG elements to the DOM. My geojson contains too many features to render at once, so my goal is to add to the map ...
1
vote
2answers
340 views

How to extract all lines that do not intersect with buffer?

I am working in ArcGIS Desktop 10.0 and/or 10.1. I have two road network feature classes in a file geodatabase. I have created a 5 meter buffer around the first one, so it is now a polygon feature. ...
0
votes
1answer
173 views

Circles created by points inside bounding box query - PostGIS

The table that i want to perform this query has 3 columns: id, the_geom and seen_count. The query i've been using to get points inside a bounding box is as follows: SELECT id, ST_AsGeoJSON(the_geom) ...
1
vote
2answers
208 views

How to intersect shape files with elevation models?

I have a high resolution digital elevation model (DEM) and a line shape file displaying a bycicle track. The DEM has 1 meter resolution. The line shape is something like 25 km long. What I need is a ...
2
votes
1answer
383 views

Help building SQL query to get a list of streets of a city

From two layers in PostGIS (osm_places and osm_roads), I would need to have the roads belonging to a certain city. It would be fair enough to get the street names of all streets in a radius of X ...
2
votes
2answers
124 views

Sextante modeler feature selection

I am trying to select grids (polygon geometry) that intersect with a building layer. I can do it by using "Select by location" tool and then I generate centroids from the selected grids. There is no ...
0
votes
0answers
1k views

Vector Intersect QGIS (1.8.0) Gives empty shapefile

I am trying to find points that fall within a polygon. Both layers are vector ESRI shapefiles. I used the fTools based intersect under Vector>GeoprocessingTools>Intersect. The output is an empty ...
2
votes
3answers
143 views

Breaking a continuous contour shapefile into smaller parts?

I created this contour shapefile and I need to break it into smaller parts so its better to manage. I also have a line shapefile of where I want the breaks. Is there a way to intersect and break them? ...
1
vote
1answer
538 views

Intersection with JTS Geometry

I want to calculate an intersection between two geometries with the intersection function from JTS Geometry. What happens, if the geometries have different SRIDs? SimpleFeature sf1=...; //SRID ...
4
votes
2answers
3k views

Differences Between the Clip Tool and the Intersect Tool

How is the clip tool different from the intersect tool in terms of how it works or the result? I don't have a specific situation in mind. I was learning about each of these tools and was curious about ...
2
votes
3answers
233 views

How to test if geometry is inside another?

I need to tell whether geometries from a shapefile are inside other geometries or not. For example, I want to test if there are trees (represented as points in trees.shp) inside the urban areas ...
3
votes
2answers
536 views

How to efficiently check for feature overlaps with Arcpy?

In an effort to reduce processing time, I am looking for ways to pre-process data within my script. I have ~18,000 featureclasses with ~500 features each (all simple circle polygons) from which I want ...
0
votes
1answer
158 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
vote
1answer
222 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
votes
4answers
598 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
297 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
380 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 ...
1
vote
1answer
309 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
940 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
329 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
votes
1answer
349 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
vote
0answers
31 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 ...
1
vote
2answers
123 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 by ...
3
votes
1answer
456 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
votes
1answer
306 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
vote
0answers
265 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
421 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
votes
2answers
125 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
146 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) ...