1
vote
0answers
39 views

How to clip polygons within buffer using QGIS?

I am trying to do the clip operation with polygons in the buffer, so far I'm getting no results. It is working for points in the buffer. Am I doing anything wrong? Basicly I'd like to include ...
0
votes
1answer
19 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 ...
2
votes
2answers
46 views

What's the use of the buffer function in field calculator?

I'm trying to find out how the buffer command in the filed calculator works. I tried to create a new field to my point shapefile (integer) with the following: buffer ($geometry, 100) but no ...
1
vote
2answers
31 views

Creating Many Uneven Buffers

Qgis 2.2, Windows 7 I am looking to create buffers around city lights (the raster). Currently, I have simple polygon buffers around the point layer (oecdminusa), but this is not accurately capturing ...
4
votes
3answers
97 views

How to shrink polygon on two sides?

I have a polygon which I know is a rectangle, although it may be at any orientation: I want to shrink this polygon by a third of the width from two sides, so that I just get the strip in the middle ...
2
votes
1answer
70 views

How to create multi-ring buffers automatically in QGIS?

I'm wondering if anyone knows of a tool or plugin for QGIS that allows for multi-ring buffers. I've found a post about doing multiple buffers one by one, but was hoping there was a way to do this all ...
2
votes
0answers
37 views

Zonal Statistics Freezing QGIS 2.2

Running on Windows; 8gb memory, 500gb HD, i5 cpu; Raster file: 250mb I am having a problem with zonal statistics advancing past 17%. I am trying to run statistics on a crop grown in certain counties. ...
0
votes
0answers
14 views

empty buffer qgis

Help! I am trying to use three buffers to select three different sets of polygons. The buffers are from a .txt file with lat and long in decimals. I made a shapefile using North America Albers (I live ...
0
votes
0answers
14 views

buffer in qgis from layer text delimited

I have a layer of polygons in British Columbia, Canada in WGS 84 which is fine. Later I created shapefile of three points (using decimals for lat and long) through the add shapefile as text delimited ...
0
votes
0answers
31 views

how to mark certain distance alongside a coastline and saved as kml to import to google earth?

Hi all I would like to mark the region of 200 nautical miles away from the coastline, how can i do this? Thanks in advanced...i already try the buffering function on qgis but dont know how to create a ...
1
vote
0answers
43 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 ...
0
votes
0answers
27 views

Zonal statistics won't work after re-projecting vector layer

I have qgis 2.0. I want to analyze raster information within a buffer of 30 miles around a vector layer of cities across the world. However, both the raster and the vector are in WGS84. I have no ...
3
votes
2answers
111 views

Creating square buffer in qgis

How can I create a buffer with square ends along a line segment in qgis? I've buffered lines using v.buffer in the GRASS plugin, but the -c option for square ends is not exposed in that interface. ...
2
votes
0answers
14 views

Eliminating/minimizing distortion in 200 NM EEZ buffers [duplicate]

I frequently need to calculate buffers of 200 nautical miles from country or baseline polygons in order to map maritime Exclusive Economic Zones (EEZs). However, I've noticed that when generating the ...
2
votes
1answer
143 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 ...
0
votes
1answer
60 views

Can I “undo” buffering of a point layer in QGIS?

I have point layer, where each point is one tree, about 1300 trees in total. I made buffers around each tree, the buffer being the height of each tree in QGIS 2.0.1. My next step was to use Spatial ...
2
votes
0answers
59 views

How to use buffer() in QGIS Value Relation field

When adding a point, I'd like to auto-populate one of its fields (the street address) setting it to a field in the nearest point in another layer (a layer containing all existing addresses). It ...
1
vote
2answers
155 views

How can I create a merged buffer in QGIS then count points that fall within it

I have a QGIS plan which shows ponds (as points in a shape file with an OS tile as a background) within a survey area. I need to calculate the total number of ponds within 1 km of each of the on-site ...
1
vote
1answer
64 views

Creating a point buffer along a road network [duplicate]

I have a road network and have added points indicating fire hall locations. How would i go about creating buffers on those points following the road line. The result am i looking for would create a ...
2
votes
2answers
92 views

Set projection/CRS in map and shapefile to produce buffer

I simply want to create a buffer of a specific size, around a single point. When I create a buffer it uses degrees/ or radians, or whatever, and the buffer is created that covers the whole screen. I ...
1
vote
1answer
112 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 ...
3
votes
2answers
105 views

Need Projection Help to Buffer Lines in QGIS

I am somewhat new to GIS in general, and very new to QGIS specifically (I took one class and we used Arc, which I don't have access to any more). I need to create buffers (1km, 3km, and 5km) around ...
1
vote
1answer
62 views

why are my buffers not lining up with their original points despite setting the layer crs as all the same crs when I reopen my project [closed]

I am having my entire project in pseduo mercator (google earth raster image) and when I create buffers for points and then open back up my project all the buffers are offset from their points. ...
4
votes
4answers
166 views

How to convert result of dissolved buffer into individual polygons?

I am wondering if there is a way to easily split results of a disolved buffer into individual polygons? E.g in the screenshot below all of these buffers are one item, can I split them into individual ...
1
vote
1answer
99 views

How to load a memory layer into map canvas an zoom to it with pyQGIS?

I would like to load a vector memory layer into the map canvas with pyQGIS. Background is, I create a memory buffer layer around point data. While iterating the points I would like to visualize the ...
1
vote
2answers
637 views

QGIS - Continuous buffer image [Heat Map]

Is it possible to have the representation like the one the figure below using QGIS? The way seems to use buffer options, but I do not know how. Does exist any plugin that helps? I am using QGIS1.8
0
votes
1answer
58 views

Why does my buffer take up the entire screen?

I am using QGIS. I am aware there is a similar question here but the solution (changing the layer CRS) is not working for me. I cannot change my CRS as I am using information for the entire ...
1
vote
0answers
81 views

Why does the buffer tool keep producing ellipsoid when I want a circle?

I want to create a 50 mile radius around a point. I've got the point as a layer. I've run the buffer tool found in Vector -> Geoprocessing Tools and set the distance to 0.5. Every time I run the ...
1
vote
0answers
93 views

How to create a buffer around a point that takes terrain elevation in account?

In QGIS, I am creating a few different buffer around points to simulate walking distances. For example, 10 minutes walk about 800m at 5km/h. Using population density, I then clip a population layer ...
3
votes
2answers
257 views

How to do a Point to Polygon analysis with multiple variables?

I have a database of almost 10k crimes, which are divided in to 10 categories and plotted on a map I also have a database of 12k addresses, which are also plotted on the map. I aim to perform a ...
2
votes
2answers
177 views

Why does the buffer take up whole screen?

I am trying to create buffers around the Hurricane Sandy path I created in QGIS (points are lat/long). I have both points from each day she was tracted and the line I created from it with Points2One. ...
0
votes
1answer
143 views

Sum of values within a buffer polygon

I need to do the following in QGIS and hope so much anyone could help. I have a vector layer with points. Each point represents a firm with the number of employees in the attribute table. I want to ...
0
votes
4answers
140 views

Buffer in QGIS/R is 650-670 m wide instead of 500 m

I am trying to make a 500 m buffer for my polyline layer. Unexpectedly, I receive buffer varying from 650 to 670 m, depending on location. As many resources recommend to use UTM before making a ...
1
vote
1answer
77 views

Add buffer only on one specific side of polygons

I have a shapefile with multipart geometry (multipolygons), namely communities (blue on the picture below). There are also lakes (white), but for these I don't have a geometry, they're just "empty". ...
1
vote
0answers
74 views

How to spatial join points attributes to layer with two (or more) overlapping buffers in QGIS?

I'm working with QGIS 1.8 and I've got 3 layers : 2 points layers, and 1 layer composed of the buffers of one of the points layer. I'd like to retrieve the informations, for the point layer that ...
7
votes
2answers
422 views

projection change to create buffer in QGIS

I am about to become desperate... I like to create buffer around several points - if possible - with a declaration of the size in km of these buffers. Just to show you what I am working with: My ...
1
vote
0answers
23 views

Creating a buffer based on area (i.e. sqm) instead of distance [duplicate]

Is there a way in ArcGIS 10.1 or QGIS (or any add-on) to create buffer based on an area (i.e. sqm) rather than using buffer distance? I'd like to create a buffer of let's say 5% of the area within the ...
0
votes
0answers
14 views

how to create several buffer around 1 point with attatched distance information (qGis) [duplicate]

hello guys, I need to know how to create several Buffer (like isochrones) around 1 Point (the distribution center). The buffers should include a distance description. For example the first Buffer ...
3
votes
1answer
179 views

How to represent Typhoon(s) wind speed using Quantum GIS / PostGIS?

I am not completly new to GIS (was taught ArcGIS at Uni) but I would still consider myself (especially compared to all these experts here) a newbie in QGIS or PostGIS. I want to display the ...
6
votes
2answers
951 views

What's the Workflow for buffering in meters/km using WGS84 layers?

I'm a little bit new to GIS, so bear with me a minute.... I'm using QGIS 1.7.4-Wroclaw and working with an SHP layer in WGS84. I want to buffer out to a certain number of kilometers from this layer ...
1
vote
1answer
391 views

Create buffer-lines in QGIS alongside Vector lines

I am currently doing a map of a farm, to see which roads needs to be repaired. Those roads are either one sided fenced, on both sides fenced or not fenced at all. I want to make buffer lines around ...
0
votes
0answers
96 views

trying to make a point to polygon attribute join with a many to many match

I am trying to match US charter schools to noncharter schools in QGIS. I have constructed a buffer of 10 miles around each charter schools and then tried a join attributes by location match with non ...
6
votes
1answer
357 views

QGIS define hexagon area around mapped points

I am using QGIS to map a number of radio antennas (for mobile network). Once I have the layer of the sites (done), I would like to assign to each site a coverage area (envelope). I could achieve that ...
9
votes
4answers
1k views

How to buffer in pyQGIS?

I'm looking for some examples to do simple python scripts in QGIS. How would I do a buffer analysis on a dataset? I can't seem to find much in the manual and QGIS python that quite matches the Esri ...
5
votes
1answer
245 views

How can I create a pollutant dispersion raster in QGIS?

As my previous questions have indicated, I am working on an air quality problem where I have a dataset of industrial emissions that consists of a location (long, lat), and an annual volume of ...
5
votes
3answers
495 views

Is it possible, in QGIS, to create buffers with a set radius, but with individual values taken from the attribute table?

I am looking to create an output that consists of an 11KM buffer around a number of discrete points, where the buffer has a value defined by a column in the data sets attribute table. Is this ...
0
votes
2answers
232 views

QGIS regular points around each polygon in a layer (vs ALL polygons)

I have a number of buffered points (some where polygons intersect & are dissolved. I'd like to create regular spaced points grid around EACH polygon -- not ALL polygons. When I do Vector -> ...
10
votes
2answers
820 views

How to buffer a line with different distances for left/right sides

How can I buffer a line in QGIS using one attribute for the left side of the line and one attribute for the right side of the line? I am trying to buffer a river with its bank width, which is ...
6
votes
1answer
298 views

How to generate non-merging buffers in QGIS?

I'm using QGIS to construct some fixed width buffers from a coastline shapefile. Is there a way to easily handle overlaps/ median lines? (I'm not sure if there's a particular term or phrase I should ...
3
votes
1answer
1k views

How to create a polygon (fixed width buffer) around a polygon in QGIS?

I have created a polygon in QGIS (in this case it describes a country's maritime baseline). I need to create a second polygon whose boundary is a fixed distance from the original polygon. (in this ...