2
votes
0answers
17 views

Performing buffering and intersection with script in PyQGIS

I wrote a script that performs the intersection of two layers: The first Layer -> layer1, represents the rivers The second Layer -> layer2, represents a set of circular dots distributed in a ...
2
votes
1answer
63 views

How to do a “fuzzy” intersection?

I have two layers that look like this: I want the intersection (or whatever the correct term may be) to look like this where the output polygons are the same as the original base layer, just with ...
2
votes
1answer
84 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 ...
0
votes
0answers
34 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 ...
1
vote
1answer
96 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 ...
0
votes
0answers
24 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 ...
1
vote
1answer
57 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 ...
0
votes
0answers
42 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 ...
0
votes
1answer
42 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 ...
0
votes
0answers
16 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 ...
2
votes
1answer
80 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 ...
0
votes
1answer
25 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 ...
0
votes
1answer
107 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 ...
1
vote
0answers
57 views

How to Simulate Venn Diagram of Buffers using QGIS?

For the sake of simplicity, suppose I have only 2 points on one layer. Point A have population of 100, and point B have population of 150. I do find buffer of these 2 points and it is intersect. I ...
1
vote
1answer
89 views

determining what polygons intersect another layer

I am attempting to establish what spatial relationship exists (if any) between two layers. I have two layers - one is a road network with a buffer of 500m, and the other is a collection of polygons ...
2
votes
1answer
214 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 ...
1
vote
1answer
60 views

Mismatch in area calculation using Field Calculator vs Group Stats in QGIS 2.0

I have two polygon files (A being my area of interest and B being a categorised land cover layer). Both layers were in the same projection (projected and not geographic). Using QGIS 2.0, I used the ...
0
votes
0answers
21 views

Program crashes when trying to do intersection.

I'm trying to get the intersection between a highways shapefile and some states in Mexico but it seems that the program always crashes. I attach the images of what I'm trying to do and the error that ...
4
votes
1answer
395 views

How to use the Intersects function in the Field Calculator of QGIS?

I would like to have an example on how to use the Intersects function in the Field Calculator of QGIS. Basically, I want to know which feature from a polylines layer intersects a polygons layer and ...
1
vote
1answer
158 views

How to calculate the intersect two shapefiles [duplicate]

I have two shapefiles. 1. the clinic buffers 500m area. 2. the postcode area. Is there a simple way to calculate the intersect two shapefiles ? I'm using QGIS Dufour. I tried to use fTools to ...
1
vote
1answer
90 views

How to perform intersect operations in the Field Calculator in QGIS?

How to use the Intersect function? How would I specify to REPLACE layer1.field1 with layer2.field2 WHEN layer1.geometry INTERSECTS layer2.geometry Is that feasible in QGIS?
2
votes
0answers
61 views

How to copy the contents of an attribute from one vector layer to another one that touches it or intersects it?

I have 2 layers that intersect, called layer A and layer B. Layer A has an attribute (X) that I want to copy wholesale (for the whole layer) to layer B, so that when object A1 intersects object B1, ...
2
votes
2answers
1k views

How to delete overlapping polygon features from one of two layers?

I really need your help! I have two overlapping layers of polygons, and i need to somehow erase the areas the overlaps. -This way i should end up with two layers of non overlapping polygons. Sounds ...
5
votes
1answer
586 views

Split polylines at polygon boundaries in QGIS

I have a set of contour lines and a polygon set containing glaciers. Because I want the glaciers to have blue contours, I need to split the contour lines at the glacier boundaries. I can achieve this ...
0
votes
2answers
155 views

Intersection between points and polygons in QGis

I have the following problem. I have a shapefile of points and a shapefile of polygons. I want to know WHAT points (not how many) fall inside EACH of the polygons of my multipolygon shp. I thought ...
1
vote
2answers
164 views

Integrate grid and polygon of municipalities keeping the biggest municipality per cell with QGIS (or another)

I have a 9x9 grid and a polygon of municipalities of an extensive area of Brazil. My goal is to have a field indicating the biggest municipality per grid cell. I've been trying with intercept without ...
4
votes
1answer
574 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 ...
1
vote
0answers
90 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 ...
2
votes
2answers
98 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 ...
0
votes
2answers
2k 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 ...
0
votes
0answers
770 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 ...
1
vote
0answers
262 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 ...
1
vote
1answer
225 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
0answers
223 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
394 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
122 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
140 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) ...
4
votes
2answers
1k views

How to Intersect between a vector (administrative areas) and a raster layer (slope)?

What I've got: 1: A vector-layer with administrative areas of my country 2: A raster-layer with the slope of the terrain of the same country (it is derived from SRTM elevation data with QGIS) What ...
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
966 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
1answer
464 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
515 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 ...
2
votes
1answer
770 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 ...
0
votes
1answer
286 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 ...
6
votes
2answers
5k 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 ...