Where features overlap

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1answer
25 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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1answer
93 views

Sextante modeler feature selection

i am trying to select grids (polygon geometry) that intersected with building layer. i can do it by using "select by location" tool. and then i generate centroids from the selected grids. there is no ...
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1answer
200 views

Creating buffers that will not overlap in QGIS

I am dealing with a .shp with a number of points in it. The distances between points range from ~300m to 5km. I wish to create a 1 km buffer around each point with as little overlap as possible. Each ...
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0answers
37 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
395 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 ...
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1answer
66 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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1answer
136 views

Intersecting polygons in Oracle

Have a polygon in table 2 with its id, no and geometry. In table 1 I have polygons with the same fields. The polygon in table in intersects with a few polygons from table 1.What I am trying to do is ...
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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
468 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
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1answer
118 views

Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
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1answer
239 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 ...
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1answer
86 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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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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0answers
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
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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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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1answer
95 views

Find intercept WGS84 coordinates between two segments defined by (Lat1-Long1 and Lat2-Long2) and (Lat3-Long3 and Lat4-Long4)

I need to determine the WGS84 coordinates for a point that is defined by the interception of two segments represented by two sets of WGS84 coordinates each (lat1-long1, lat2-long2) and (lat3-long3, ...
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1answer
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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1answer
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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1answer
73 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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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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2answers
300 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 ...
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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
57 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
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
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
77 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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0answers
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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0answers
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 ...
2
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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
46 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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1answer
62 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 ...
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0answers
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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0answers
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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2answers
645 views

Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
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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 ...
1
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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 ...
2
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2answers
109 views

How to check if vertex exists (on polyline) based on location of point layer using ArcPy?

Using ArcGIS for Desktop Advanced 10.1 (with all extensions) I am building a centerline network that will be used by a MapObjects program to do routing based on "turns at any vertex" (as opposed to ...
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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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0answers
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 ...
0
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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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0answers
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
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: ...