Where features overlap

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29 views

Closest point on a line segment from point outside the line

From the above pic I found the value x from line (p1,p2) and point a. Using y=mx+b and an imaginary red line which is perpendicular to the black line having slope -1/m and the intersecting point ...
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38 views

Counting self intersections of linestring using PostGIS?

Is there a way of using PostgreSQL + PostGIS for finding the number of self intersections in a linestring? I have a linestring that goes forward but in circles, and I need to find the number of times ...
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1answer
68 views

Calculate population coverage

I am relatively new to QGIS and hope I explain this right. I am looking at the percentage of an population that has geographical access to healthcare. Therefore I have one shapefile with village ...
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13 views

Basic Intersect in mysql

I've looked all over but can't find a simple snippet of mysql spatial intersect. Does mysql support it? Does anyone have a working exmaple? Thanks
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1answer
67 views

Iterating over all features in featureclass to intersect them individually with polygon using ArcPy?

I've got a point featureclass, and I'm trying to individually intersect each feature with a polygon featureclass to get some information about which polygon each feature is in. I did one intersect ...
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1answer
87 views

Calculating countries flown over on flight path

Say I have two airports given. I can then get their coordinates. Now that I have the beginning and end coordinates I can draw flight-path from the two locations. Now my question is that given two ...
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1answer
48 views

How do i rescale feature classes of different scales for intersect analysis?

before I intersect 2 feature classes of different scales (e.g. 1:200,000 soil map and 1:25,000 land use map), should I rescale them like how u would resample raster datasets to the same resolution ...
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45 views

Intersecting great circle arcs and polygons

I am trying to find the point of intersection between a great cirle arc and a polygon. I am working in long/lat, where I am given the endpoints of the great circle arc, A and B, and the vertices, C, ...
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23 views

Get attributes from intersecting lines to label generated intersection point

I have an urban road network (as a feature class), consisting of only polylines. I have to make a database of all the intersections between the streets. The problem is that as I generate those ...
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2answers
71 views

Is it best to use multipolygon or polygon features for large intersect operations?

I have two large layers that I want to do intersect operations. One is municipalities and the other is landuse. Right now, the landuse layer is of MultiPolygon type that is, for the entire state, I ...
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52 views

postgis finding lines that touch and update

I am not much of a postgis guy so please bear with me. I have a subset of lines representing exits and roads around those exists. Main roads and exists can be distinguished by their class attribute ...
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33 views

How to overlay polygons that are in the same layer

I need to INTERSECT many polygons that are in the same layer. Actually each polygons from my layer represent an area of influence from one specific bird species. Since I used to use ArcMap, I found ...
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74 views

Automating Intersect between two polygon layers

I have a spreadsheet that has county-level occurrences of around 1000 species within the US in the column headings (Species State County). Thus, for some counties there may be multiple species. I ...
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31 views

Determine the list of circles (from 100K circles), that overlap with a given polygon

This question was asked on StackOverflow, came here because no response has been posted so far. Existing data structure we have polygons represented as an ordered list of lat/long coordinates and ...
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1answer
38 views

How can I add data from Points to Polygons (intersected or near) in ArcGIS 10

I'm using ArcGIS 10. I have a Point and a Polygon shapefile. The Points have a NAME field filled, and the Polygon the same but emptied a minority (350 out of 3000). I need to catch these names from ...
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1answer
58 views

Setting a value on a raster where a polygon intersects cells

I reviewed all of the supposed 'answers' and I just do not see that they really answer my question. Mostly because the ones I'm reading are setting values either inside or outside a boundary. So let ...
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1answer
80 views

Intersect between polygonal shapefiles error

I'm encountering a problem when I try to intersect two different shapefiles. They are all new shapefiles I created to descibe the land cover and the land use of a city. The problem occurs when I ...
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52 views

Using Geometry commands in MS SQL Server 2008

I am looking to find the most effect way to use SDE and ST_Geometry SQL commands. Can anyone tell me how/what commands I might use to perform a spatial query in MS Sql Server 2008, to Select property ...
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23 views

How to measure water ties

I was using Arc Gis to measure water ties from the edge of buildings. It was so easy, I just had to click on a circle and it would show the distance on the bottom of the screen. I would measure from ...
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1answer
32 views

Intersection Type Data

Would anyone have any input as to where I could find a table/shapefile/feature class that describes the intersection type of roads? I've looked into TIGER roads, StreetMap premium, OpenStreetMap ...
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1answer
47 views

Overlap or intersect two choropleth [closed]

I have two choropleth of the same area but with different concentration data and I need to overlap them. My aim is to highlight the areas of intersection between the points with the highest ...
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34 views

Split polygon into four with respect to single point

Some days ago one of my colleague came to ask me a query related to Geometries. The situation is as....There is one Polygon(suppose a city polygon) and there is one point(suppose user's current ...
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40 views

How to intersect more than 2 layers in QGIS

I have a dozen layers, some intersecting with others. Using the Intersect tool only allows 2 layers at a time but can you add extra layers to find where it intersects? Even if it's 3 layers as shown ...
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1answer
38 views

Summing the number of intersections with a separate buffer layer

I have dabbled with ArcGIS and QGIS a bit, and I consider myself a self-taught beginner with a whole lot to learn. So, I have two layers: 1) census blocks, and 2) point data. My goal is to calculate ...
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1answer
97 views

Finding closest Intersection between line strings (PostGIS)

I want to find the distance between one point (excavation sites) and a line (rivers) for the cardinal directions. What I thought would be the easiest way is to draw lines between the excavation site ...
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15 views

Can a joined-layer have its attribute changed depending on what layers are selected/deselected?

Using QGIS, I have a polygon-grid layer which covers everything, Layer_All joined with 2 other grid layers: Layer_1 and Layer_2, both of which intersect at various points. I would like Layer_All to ...
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1answer
40 views

Trying to understand / troubleshoot intersection behavior of postgis

I'm trying to calculate the percent of intersection between two polygons using postgis. I was able to do so successfully for 90% of my polygons, but about 1500 have very unexpected values. I ...
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1answer
72 views

Intersection of polygons QGIS 2.2

I have a polygon layer with many circle polygons in it, which are overlapping each other. I now would like to cut of the overlapping areas at their cutting edge: I use QGIS 2.2 and couldn't ...
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1answer
79 views

How to set tolerance value of ST_Intersects query in TileMill?

I want to place river names in Tilemill. I use "text-dy" to displace label from the center line of a river. But for labeling polygonal rivers, names extracted from lines are used too. So at a small ...
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1answer
34 views

How to detect if a point lies inside a building?

My main motive is to detect if there's in any infrastructure nearby to a given point in a certain radius. For this I am using Places api and using nearbySearch method of it. The problem in this is ...
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26 views

How to intersect widget using script python arcpy and geoprocessing service? [closed]

Is it possible to develop an intersection widget with geoprocessing service using script python arcpy? I try to do that with ModelBuilder but after publishing, in geoprocessing service i don't find ...
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1answer
38 views

How to output parts of layers (shapefiles) that do not intersect using ModelBuilder?

I have two layers (shape files) that I want to select what do not intersect, to after all make a kernel of it. How do I do that in ModelBuilder without scripting? If someone can help me, even ...
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38 views

How to use Intersect tool in ArcObjects

I'm trying to use the Intersect tool in ArcObjects SDK Java with two feature classes. Here is my code: public void intersectTwoFeatureClasses(Object in1, Object in2, Object out) throws ...
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1answer
61 views

How to intersect more than two layers? Is there a quick way?

We have three layers, income, obesity and fast food restaurants for England and we wanted to find districts where they all intercepted. So we did a combination of two layers at a time to find where ...
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3answers
1k views

How to find if two polygons Intersect in python?

I'm looking for an algorithm, high level solution, or even a library which can help me determine if two polygons intersect, in Python. I have the vertices of the two polygons (These are single part ...
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3answers
115 views

How to count points once with overlappying polygons?

All, We're using parcel data (polygon) to count student locations (point) based on parcel type. We're doing this using SQL and the ST_Intersects function. It works great, except the City and County ...
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3answers
89 views

Geometry vs geography for line-to-polygon intersection

I have two WGS84 NAD83 shapefiles, one polygonal, the other containing lines: Geometry: Polygon Feature Count: 1294 Extent: (-79.761059, 44.991143) - (-57.105486, 62.582865) Layer SRS WKT: ...
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28 views

Quickest method for determining which postcode is 2 miles north of original postcode? [duplicate]

What is the Quickest method for determining which postcode is 2 miles north of original postcode? For instant L17. I know how to determine the distance between 2 points as below, but the above ...
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1answer
44 views

Hard to get my head around, generating average price for houses in each quadrant

I'm able to determine the average price of houses sold in a particular area (like the squares on image below) dependent upon postcode. Although I can generate the average sale price for a particular ...
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2answers
85 views

Is there an average size for British postcodes?

Is there an average size for British postcodes? Or a method of determining the size for a particular British postcode? Thanks. Considering creating a related program and this would be valuable ...
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1answer
18 views

How to select the identities of a layer present just in one identity of another layer

I'm a student approaching to QGIS 2.0.1-Dufour. My goal is to know how much identities of a layer are present just in one identity of another layer. I tried both with the tools "spatial query" and ...
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31 views

GRASS GIS - v.select- ERROR: bad allocation -

I'm quite new to Grass GIS. I have two vector maps, one of a grid (each grid cell is a polygon) and one of a much larger polygon. I've been trying to select the grid cells that lie completely within ...
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2answers
41 views

How can I populate a field of the polylines to indicate if they intersect?

I have two feature classes, one ploylines, one a buffer. How can I populate a field of the polylines to indicate if they intersect?
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94 views

How to simplify a self intersected / self overlapped polyline using ArcObjects?

I have a self intersected polyline, how can I break it into 5 records stored in the same table using arcobjects? (splited by vertices and the intersection point) Here is what I have got and it ...
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1answer
97 views

Cut polylines at intersections in QGIS (or how many km road for each country)

I want to measure how many km a road stand on each country it intersect (i.e. how many km of the european road "E45" stand on Italy, Austria, Germany, and so on). I have a polyline-shapefile with the ...
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1answer
53 views

How do I convert OS coordinates (X and Y) to longitude and latitude coordinates?

How do I convert OS coordinates (X and Y) - Eastings and Northings to longitude and latitude coordinates? For example X and Y below X (Eastings): 347904 Y (Northings): 287484
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1answer
87 views

How do I figure out the grid references (Eastings and Northings) necessary to create a circular 1 mile radius around one location?

How do I figure out the grid references necessary to create a circular 1 mile radius around one location? For instance: Grid Reference: SO 47904 87484 X (Eastings): 347904 Y (Northings): 287484 ...
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92 views

PostGIS: How to distinguish overlapping routes (i.e., LineStrings) based on their direction?

I have a set of routes which are represented by LineStrings in my PostGIS database. These routes represent journeys that people make. I want to come up with routes that (a) overlap, and (b) have the ...
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1answer
68 views

Verifying the number of times a line crosses other lines

I have a series of lines that represent streams. I have a stream line and two flowpath lines in one feature class and two banklines in another feature class. Total of five lines. I then have a feature ...
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35 views

Intersecting Overlapping Polygons Individually in ArcGIS

Map Layers: -Census Tract Shape File w/Population Data -Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...