QGIS is a user-friendly, cross-platform GIS application licensed under the GNU General Public License.

learn more… | top users | synonyms (1)

2
votes
1answer
240 views

Problems with NAD27 projection in QGIS

I have some data that is in NAD27, but I am having a hard time displaying it in QGIS. I think that the problem is with the CRS. I cannot seem to find the correct NAD27 option. The closest one seems ...
4
votes
1answer
230 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
4
votes
1answer
789 views

Revealing the different layers of a shape file in QGIS

Shapefile I am referring to is 'NUTS_RG_03M_2010' which is together with several other Shapefiles available in a ZIP file on the Eurostat web site. the ZIP file the available map sets at Eurostat I ...
0
votes
0answers
139 views

How do you normalize a field in Qgis symbology?

I'm trying to normalize a field in symbology in Qgis but there is no normalization option like in Arc. I've tried to add a field to the attribute table and use the field calculator to do the ...
3
votes
2answers
150 views

How to modify two polygons which have common point and line at the one time

I would like to modify two polygon at the one time because these two data has same point and line. Is it possible?? In the present circumstance, I have to modify polygon one by one. First, I ...
1
vote
1answer
135 views

How to remove terracing from Civil3D GeoTIFF export?

I've received a GeoTIFF DEM that was exported from Civil3D and at every contour there is a distinct terrace created when I process an aspect or slope in QGIS with the GRASS plugins. I've looked ...
4
votes
1answer
135 views

Problem with custom projection definition in Qgis

I want to define a custom crs valid for Mexico. The context is that older cartography in Mexico is based on the NAD27 datum. I wanted to test the following proj4 string +proj=longlat +ellps=clrk66 ...
3
votes
0answers
702 views

How to join data from a CSV to a shapefile using QGIS

I'm new to GIS and new to StackedExchange. I need help joining a CSV of Accessibility data to a LSOA shapefile in QGIS. The process explained here does not work for me and I don't know why. The ...
3
votes
3answers
766 views

Auto-calculate field (area or formula)

I'm wondering if anyone has any insight into the potential to auto-calculate the value of a field, either area or distance (ideally) or a formula (based on the values of say 2 other fields, or an ...
2
votes
3answers
7k views

How to convert shape files (.shp) to Cad (.dwg ) format using Quantum Gis 1.7.0?

How to convert shape files to .dwg format using Quantum GIS 1.7.0 ? Thank you
2
votes
1answer
94 views

Can you change the location of .qgis from the home directory to another folder on Windows in QGIS1.8?

Is it possible to change the location of the .qgis folder to another location ( for example on a network drive H:\ ) in Windows?
1
vote
0answers
123 views

How do I fix this QGIS sextante error? NameError: name 'sextante' is not defined

A colleague of mine posted this the other day. We haven't got any nibbles yet and I wanted to elaborate on the issue. We are having trouble running the r.mapcalculator function and receive the error ...
1
vote
1answer
346 views

How to create layer from shapefile in QGIS?

I have a road network shapefile that I want to use to create multiple maps from it, each based on some selection of original shapefile. For example, I want to show all highways with some custom ...
0
votes
1answer
211 views

How can I find and fix broken raster metadata using QGIS?

I have a raster (TIFF) hillshade image that I would like to use in a mapping project. However, I'm having a hard time lining it up properly in QGIS. Through a series of investigations, I have ...
1
vote
1answer
313 views

How to create new columns in QGIS by writng Conditional query on other columns of attributes table

First of all, sorry, I couldn't phrase my question better. So I want to be able to add a new column in my attributes table, say B, and it's value should be 1 if Column A's value is 1 and 0 if Column ...
2
votes
2answers
81 views

How to 'trace' areas from the layer below?

I have some Ordnance Survey vector data for my local area. I want to create a new layer and on it 'trace' some of the areas, fields, verges etc from the layer below with the intention of then ...
0
votes
1answer
278 views

How do I add a Corel Draw map as .dxf file to QGIS and how do I georeference it?

I have a vector data map of Poland, which I exported from Corel Draw. I can display the map in QGIS. At first the boundaries and subdivisions are only displayed as lines, after saving the data as ...
1
vote
1answer
77 views

I have a .sid image but can't figure out the CRS

There is a .map file: OziExplorer Map Data File Version 2.2 Tiritir_2.sid C:\OziExplorer\Maps\Islands\Tiritir_2.sid 1 ,Map Code, Geodetic Datum 1949,WGS 84, 0.0000, 0.0000,WGS 84 Reserved 1 ...
0
votes
0answers
136 views

Qgis ,Area Management of Dealer Network - Analysis of Population versus dealer location and sales performance

I want to analyse a Dealers retail sales performance by location , measuring sales versus population in total and social class etc. I have the shape file for the population of Ireland which includes ...
1
vote
3answers
2k views

QGIS Raster Calculater Syntax

I am trying to use the raster calculator in QGIS to combine a number of rasters. I want to calculate a mean, this is easy: (raster_1@1 + raster_2@1 + raster_3@1) / 3 I then want to create a max. ...
1
vote
1answer
521 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
1answer
295 views

Error running mapserver export in quantum gis

I have a project in Quantum GIS that I need to export to a .map file using de plugin mapserver export. I fill all the forms but I get this error when running the app. Any ideas of what is ...
1
vote
1answer
251 views

Automatic bulk snapping with FOSS

I'm looking for a tool that would be able to automatically snap features closer than a given distance. Is there such a tool/plugin for QGIS/GRASS/OpenJump? Would it be possible to achieve that with ...
3
votes
3answers
360 views

How do I sort polygons by their latitude?

We have a set of polygons which we would like to sort and number according to their latitude. This will make it easier for local authorities to relate to the numbers of the objects. I have looked ...
2
votes
1answer
477 views

Output of QGIS raster clipper not as expected?

My goal is to clip a raster with a polygon in QGIS 1.8. Based on an article I read, this should be a pretty straightforward task. However, the output appears to be empty. The raster produced is the ...
1
vote
1answer
680 views

How to draw grid cells in QGIS?

I have one ASCII text file with eight columns. The first four provide the x-coordinates (e.g. longitude) of the four corners of a grid cell, while the last four provide the y-coordinates (e.g. ...
7
votes
2answers
675 views

How Can I Make QGIS Stop Blinking Every Time I Pan?

The way QGIS draws the canvas when panning is quite annoying. If I pan the map even a little bit everything goes blank for a second or two before the layers are drawn. It looks like this happens only ...
3
votes
1answer
81 views

Get rid of raster grid cells that are less than 1

I'm using QGIS to work with raster data. I have a raster dataset of a country where each grid cell is assigned a number 1-100. However, the raster is in the format of a rectangle based on the extent ...
2
votes
1answer
84 views

How to interpret the OSGeo4w software version under Advanced Install option?

When choosing to install QGIS Desktop using the OSGeo4w advanced install option, I noticed that there are what looks like ambiguous software versions to choose. For example, currently QGIS Desktop ...
0
votes
1answer
772 views

Wrong coordinates in data when projecting in world map (qgis) [duplicate]

Possible Duplicate: How to find the proper coordinate reference system with two sets of data using different measurements or too convert one system into another I'm fairly new to the GIS ...
5
votes
2answers
409 views

Spatial Analysis with Factors/Classifications

When doing analysis on spatial data with associated information that is numeric, it is possible to use techniques such as Kriging or Interpolation or Cluster Analysis to find out interesting ...
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 ...
2
votes
1answer
856 views

How to apply a graduated renderer in pyQGIS?

Just trying to run the following code already given in the pyqgis cookbook to create graduated colors symbology (as in example with 2 classes) I define the source info for the shapefile but when I ...
1
vote
1answer
395 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 ...
0
votes
1answer
414 views

How to convert a finished project in QGIS to PDF

I have finished my project and need to convert it into a PDF file. How can I do it?
1
vote
1answer
328 views

matching georeferenced jpg with GPS data in WGS84 [closed]

I have imported my georeferenced jpg which I believe (on the basis of metadata in xmml file) to be in the NZGD2000 TM coordinate system. metadata: Origin: 1.76759e+06,5.94938e+06 Pixel Size: ...
6
votes
1answer
493 views

How to label a lot of nearby points?

I am currently working with a lot of points of which every point has to be labeled. I am already using the "Easy Custom Labeling" tool to move the labels and create lines to connect points with ...
0
votes
0answers
731 views

How to resample a raster in QGIS?

I've got a boundary file that I would like to resample the raster file from a 30m grid to a 10m grid inside the boundary file. When I try and do it in Qgis or Grass all I get is one big raster cube ...
0
votes
0answers
305 views

How to change shape file's extent in QGIS

I have created a network from 3 shapefiles using GRASS. While haveing problem to perform a network analysis with it, I've been told that the extent of the network shouldn't exceed that of the original ...
0
votes
2answers
627 views

Python module “shapely.wkb” missing

I am trying to follow a tutorial from here http://qgistips.spatialthoughts.com/2012/12/find-neighbor-polygons-in-layer-in-qgis.html#more I have downloaded the relevant python script and edited it as ...
6
votes
1answer
440 views

QGIS line style

I found the latest QGIS has a great tool to create complex styles, however looks like one small but very useful thing is missing, or I can't find it. I'm trying to create a line style something like ...
1
vote
1answer
282 views

Polygonize function doesn't overlay the shape file over the raster file

To convert the raster into a shapefile I use raster->conversion->polygonize but QGIS doesn't open the new layer overlayed the first (the raster) but reflected above it. I read this question ...
3
votes
1answer
354 views

color gradient (or color ramp) in Arcgis and Qgis

I am currently working on my thesis and I would like to ask you: does anybody know the mathematical formula that calculates the color gradient in Arcgis and Qgis? In other words, which mathematical ...
1
vote
1answer
249 views

Displaying only points within a polygon I created in QGIS?

Thank you in advance for any advice you might give me. I am new to qgis and believe what I'm asking is probably fairly basic. I am trying to map policing activity in NYC for two areas: one area in the ...
0
votes
1answer
94 views

Should a GDAL Plugin be the same version as GDAL aready built into QGIS

Should a GDAL Plugin be the same version as the GDAL that's aready built into the QGIS version installed? Or,can another different version of GDAL be built and it installed as a Plugin for QGIS, ...
3
votes
0answers
166 views

How to achieve better Dissolve results?

I applied the Vector>Geoverarbeitungswerkzeuge>Auflösen (Dissolve) on a zoning plan (see picture zoning plan). I used the attribute village name as the dissolving criteria. The resulting geometry for ...
3
votes
1answer
218 views

Can I color different layers with the same pseudocolor color map?

I have multiple DEM layers in my map (downloaded from atlas.louisiana.gov/lidar), but I cannot seem to get the colors to line up. You can see in the attached image that the colors are not continuous ...
2
votes
2answers
119 views

What specifically is an 'attribute' and how does it work with the related chart?

I'm a new QGIS user (and GIS technology in general) and I'm trying to learn its fundamental features. I have a big dilemma about vector shapefiles, and points in particular: basically, I don't ...
4
votes
1answer
712 views

How to break (both) lines at their point(s) of intersection in QGIS?

I'm working with a road network where some of the road segments cross each other but no point is inserted at their intersection. Is there a way to break these line to shorter lines at their points of ...
3
votes
5answers
1k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...