1
vote
0answers
22 views

How to Interpolate very large datasets in QGIS

I am working with a very large set of point data, (XYAttribute) which I wish to display as a raster. I've been using Interpolate, this is successful but very slow. I have other programmes that simply ...
1
vote
1answer
29 views

QGIS 2.4 Layout View pdf/raster file export moves points

I created a map, using a google basemap (openlayer plugin) and imported a table as a csv file (containing a name of a city, latitude, longitude for wgs84 and a row named "amount"). It displays ...
2
votes
1answer
41 views

Delete duplicate polygon nodes with PostGIS

I'm trying to delete duplicate nodes from a shapefile with QGIS, but after running the tool to delete it, nothing happens and shows the same errors. I thought that maybe importing to postgis could be ...
1
vote
0answers
20 views

How to compare two sets of points in QGIS?

I have two point layers with XYZ data: 1 set are points measured at the field and the second set is a Lidar data set. I want to check the accuracy of the lidar in comparence to the measured data. Is ...
0
votes
0answers
30 views

Reading Points as PolyLines

I'm currently developing an Android app where I need to show some information on a map, which is stored as Shapefiles (.shp + .shx + .dbf). I noticed that when the shapefile is opened in QGis, a nice ...
0
votes
0answers
29 views

QGIS Rasterization of points

I have a point vector layer and want to make it a raster. Trouble is that many points are very close to each other, so unless I specify a very small resolution of the raster cells, likely several ...
2
votes
1answer
59 views

Calculate distance between point and linestring and how to represent that on QGIS?

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
2
votes
2answers
70 views

QGIS polygon centriods - How are they created?

I have been using QGIS to analyses spatial data and I created polygon centroids with the vector geometry tools. Now for a report I have to explain how these centroids were created. I have not been ...
0
votes
0answers
34 views

Can I create a cross section from points along a line without using a DEM in QGIS?

I have a set of points perpendicular to a river and would like to present a cross section of them. Like a simple graph in Excell for example, with Z as y axis and distance along the line as the x ...
3
votes
2answers
132 views

How to automatically draw lines with a given angle from one single point in qgis 1.8?

I'm new to qgis so please be patient. I need to draw a bundle of lines all originating from the same point and with a 10° angle between each line (e.g. lines bearing at 0,10,20 ..90..110..220..350). I ...
3
votes
0answers
46 views

Is there a “Disperse Markers” tool for QGIS?

I am using ArcGIS, but either I would like to use QGIS and maybe want to switch completely later. A have a point overlapping problem, as a result of geocoding of addresses. I have not found any ...
0
votes
0answers
67 views

PyQgis: How can I “append” features to a Vector Layer instead of “stacking” them?

As I read data from a text file and add points to a QgsVectorLayer (as well as related attributes), each new record gets 'stacked' on top of the previous one in the Attribute Table (and within the ...
0
votes
1answer
59 views

Generating points from chainage and offset

I have a polyline layer and an external csv containing road sign data. The csv has unique ID of the polyline, chainage along each unique segment and an offset. I have access to ArcGIS, MapInfo and ...
0
votes
0answers
17 views

Statistics on matching point layers ignoring nodata values in QGIS

I have a large area and a street crossing this area. Both are vector point layers in QGIS. The large area contains -99 as NoData value. I already created the intersection of both as a new layer. I ...
2
votes
2answers
70 views

How to convert a point layer to a raster grid that shows the frequency of points per cell in QGIS

I have a point layer that shows the distribution of a species. Is it possible in QGIS to convert this point layer to a raster grid in which the value of each cell corresponds with the amount of points ...
1
vote
1answer
34 views

QGIS hides few graduated points after reopening project

I have a strange problem in QGIS 2.2 (problem is also present in QGIS 2.1). When I add a point (shapefile) layer, apply graduated style and change point size, everything looks fine. Then I save ...
1
vote
1answer
168 views

Split a line feature using nearby points

I have a line shapefile and a point shapefile, and the line has its own segments and its attribute table, the point shapefile has points near the line above, not on it and the close ...
0
votes
0answers
43 views

How to create a point representing a polyline?

How do I convert a line (usually 2 vertices but can be more) into a single point in QGIS? I did it a couple of years ago using a build-in tool in ArcGIS 8 or 9 I think but have no idea how to do it in ...
1
vote
2answers
43 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 ...
1
vote
1answer
49 views

Identify geographic location to points

I am quite new in QGIS and I really need your help. I have a map of Kenya divided into 68 districts and I have coordinates of 30.000 schools. The points have one variable besides the latitude and ...
2
votes
1answer
346 views

Problem creating point shapefiles programmatically using python in QGIS 2.2

I am trying to create a point shapefile in the memory buffer (for a temporary label) and then zoom to the extents on this buffer. The working (in version 2.1) test code for this is: def ...
1
vote
2answers
165 views

Draw line between points from multiple datasets

I have 2 point datasets and want a tool or script to draw a line between all points in one dataset to all the points in the 2nd dataset. Is it possible? I have tried ESRI "Point Distance" and ...
3
votes
2answers
211 views

Line start and end nodes: determining what is a junction

I have a layer of points and polylines and want to determine which points are road junctions. I currently have all start and end nodes within 3m of my road network as a layer. However I cannot ...
2
votes
0answers
42 views

What is an Orphan point?

MY apologizes about the next doubt, but I can't understand what is an orphan point. I am using QGIS with a module to apply the Linear Reference System (the module is called "LRS"). During the ...
1
vote
1answer
68 views

How to map flood areas from a set of points containing surface and height of water?

I am working on the damages made by the typhoon Haiyan. I use QGIS 2.0 with extensions and toolbox, and MapInfo. I have vectors, rasters of the place. I want to map the flood area along the ...
1
vote
0answers
27 views

Creating contours from partial data set

Is it possible to create contour lines based on part of the points and not the entire dataset?
3
votes
1answer
114 views

How to horizontally align irregularly shaped point symbol to vector layer in QGIS?

Fairly new to QGIS and searching a method to graphically align my point symbols in the direction of the vector. The symbol represents a water valve in an irregular shape in close proximity to a vector ...
0
votes
1answer
79 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 ...
1
vote
2answers
205 views

TIFF/Raster to Point shapefile question

Apologies in advance if this question is incredibly basic, but I've been googling around and I just don't know where to start. I've downloaded some nighttime luminosity data from NASA, and the data ...
0
votes
0answers
76 views

Point features disappear when moved using QGIS 2.0

When I move, either by the node or the move function, a feature symbol on the map canvas, it simply disappears, not just the label, the whole thing. CTRL-Z brings it back. I'm using a MAC OS-X. I've ...
5
votes
3answers
273 views

How to visually sort the order of Points with QGIS, GDAL, …?

The following Points layer is the basis of a rendering in a Android application. Android allows to draw a shape from the provided points. I cannot use LineStrings. However, the order of points ...
1
vote
1answer
89 views

What is the best way to display point data (with standard deviation) using QGIS/SAGA/Manifold? [closed]

I would like to display point data values (indicating biomass at a point) but also to show the standard deviation value for each point. What would be the best method to do this in QGIS (I'm a basic ...
1
vote
1answer
87 views

QGIS how to compute a trendline of two point lines?

Does anyone know how to compute a trendline for two lines of points? I have two lines of points of a 10 km long urban road. 1st line is one driving direction and the 2nd line of points ist the other ...
2
votes
1answer
32 views

Get coodinates from point shapefile

I converted a line shapefile to points as you can see in the attached image. Is there a way to know the coordinates of each point? Any help would be really appreciated! PD Im using QGIS 1.8.0
0
votes
1answer
144 views

How to display coordinates of a point in a projected cooridante system?

I want to check the coordinates of a point. On selecting this point in ArcGIS it displays a latitude and Longitude . In ArcGIS I found an option in 'Identity Tool' that the Latitude and Longitude ...
1
vote
0answers
54 views

How to auto-fill a new point vector in a vector layer?

When I work in-situ I manually add points in my shape-file. I would like that when I add a new point some attributes would already filled with values calculated programmatically. E.g in my first ...
0
votes
1answer
56 views

QGIS proximity raster with extent beyond original coverage?

I need a raster coverage of distances from points outside the geographic region of interest, and am having trouble doing this with QGIS. Questions like this one (Calculating distance to points in ...
1
vote
0answers
29 views

QGIS rule-based point style responding to number of co-located objects?

I am mapping the geolocated location information for 5.5k Twitter profiles as point data. Many of them have the same location ie "London, UK" meaning that they return identical coordinates. On the map ...
2
votes
1answer
182 views

Moving a shapefile point to specific coordinates

In QGIS is there a simple way to move a shapefile point in a shapefile point file to specific coordinates? Without exporting the points to WKT changing the x,y values and then importing the WKT via ...
0
votes
0answers
23 views

How to divide my area into adjecent polygons containing 80 points each? [duplicate]

I have a couple of thousand points in my dataset. I need to create clusters that each consists of 80 points. The specific selection of which points to put into a cluster is not critical - only the ...
1
vote
1answer
69 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. ...
7
votes
2answers
817 views

How to remove small “salt & pepper” polygons from a layer?

I have a map made up of multiple polygons, with a few hundred thousand points very small polygons on within it. I need the larger polygons, but not the points small polygons. How do I select and ...
1
vote
2answers
100 views

QGIS point sampling tool really slow for polygons?

I have a large field of randomly distributed points (100,000 of them to be precise), and I'd like to get values for a variety of raster and polygon coverages for each point. I've been using the QGIS ...
0
votes
0answers
107 views

Create shape file with point

I am trying to create a .shp file with Point shapes. I am following this tutorial: http://docs.geotools.org/latest/userguide/tutorial/feature/csv2shp.html I create the project, no syntax error and ...
1
vote
1answer
301 views

Postgresql view with Point geometry returns QGIS error “(the_geom) sql = is an invalid layer and cannot be loaded”

I want to create a Postgresql view using point data. When I create the view, the geometry_columns table updates appropriately. Attempting to load in QGIS produces the error “(the_geom) sql = is an ...
2
votes
1answer
229 views

How to calculate mean coordinates from big point datasets?

I know there are several questions related to speed issues in QGIS, but I am having problems when running Ftools. I have a vector with ~70,000 points in it. When I run the generate mean coordinates ...
1
vote
1answer
81 views

Snap mean coordinate to layer in QGIS and creating MCs for multiple shapefiles

1: I wish to create a mean coordinate for a group of points. However, I would like the new point to be snapped to the nearest point from the set of points used to generate it. How might one go about ...
0
votes
1answer
68 views

How to create more than one mean coordinate in QGIS?

I have a point shapefile with several thousands of points in it. I've split the points up into spatial groups using a vectorgrid and pointcount. I wish to create a mean coordinate for each group of ...
2
votes
1answer
127 views

How to convert a line to points?

I'm working with QGIS and I want to convert a line into many points, does someone know how? Thanks.
3
votes
2answers
401 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 ...