Tagged Questions

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

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1
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1answer
366 views

What is the best way to ortho-rectificate image from the plane?

I am very new in GIS and I am trying to ortho-rectificate my images. But after putting it on the map I see that results are not precise. We have images taken from the airplane, it's longitude, ...
1
vote
1answer
143 views

How to find matching pixel values in seperate rasters

I am looking to scan two separate rasters, capture the pixel information, then draw a polygon of the matching pixels. any thoughts? I am at a loss. Edit: I have two aerials, both are in ...
0
votes
1answer
49 views

What could cause issues migrating a Python plugin to another Windows version? [closed]

I am developing a plugin in my laptop and the plugin runs well. So, I installed the same version in other computer and the plugin doesn't run well. Sometimes I develop the code in laptop, sometimes in ...
0
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1answer
81 views

QGIS Web Url paramater zoom / scale

I have a link for wms in QGIS Server like this: ...
4
votes
1answer
2k views

QGIS on Mavericks

I have been trying to install QGIS on Mavericks and I have failed. Prior to installing QGIS, I installed GDAL using homebrew. I also installed Numpy, SciPy and pyqt using the detailed instructions ...
1
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2answers
97 views

How to create buffer zone in metres for OSGB1936 layer?

I am creating buffer zones in metres on top of UK Ordnance Survey map files that are in OSGB1936 which uses degrees. How do I draw the buffers in meters? Many thanks
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0answers
149 views

Best way to join and handle multiple attributes related to the same feature

this is not going to be a question, I'm just trying to find some advice. Suppose I have a point shape file (for example just 2 point, actually I have many more points) representing water control ...
0
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1answer
83 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 ...
0
votes
1answer
59 views

How do I get basic statistics on a field in a joined table?

I have a shapefile to which I've joined a table, matching with an ID field. All the fields of the table show up correctly when I open the shapefile's attribute table. But when I go into ...
0
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0answers
31 views

QGIS - identifying polygons and distances along the edges of a superset

I have two layers of polygons. layer A is a superset of dissolved polygons from my other layer, B. Using QGIS, how can I determine polygons in B, that lie along the edges of A? There would be some ...
3
votes
2answers
214 views

Working with GDB in QGIS 2.0 - plain language instructions please!

I'm a QGIS user running v2.0 (Dufour) on Mac OSx10.8.5. I have some data in .gdb format and need to access this and work with it in QGIS. I'm a relatively savvy computer user, but not at all a ...
1
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0answers
128 views

Problem installing QGIS on Mavericks. Says I need 10.6.8

Trying to install QGIS for first time on a Mac OS X 10.9 (Mavericks). Loaded up all the prerequisites (GDAL, etc.) but the QGIS installer tells me "QGIS requires Mac OS X 10.6.8.". Saw that QGIS is ...
2
votes
1answer
84 views

How to translate (reposition) a .tif raster layer?

I'm starting to use QGIS for my thesis (environmental physics) and have to admit I'm pretty ignorant about it - I've always used Mathematica or Matlab. My problem is: I have a raster layer, in .tif ...
1
vote
1answer
161 views

Select polygons by attribute belonging to another layer

I'm a recent QGIS user. I have a shapefile A with a series of polygons indicating land use of an urban region (urbanised areas). Now I want to select them in relation to a second shapefile B with the ...
1
vote
2answers
283 views

Import Esri/ArcGIS .e00 files to QGIS on Linux (getting error message)?

I can't seem to import Esri .e00 files into QGIS, and I can't figure out why. I'm trying to import files I've downloaded from ...
0
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0answers
53 views

Loading QGIS and files from Python's use of os.system?

I am trying to open QGIS and load two files using the following code in Python: os.system('qgis D:\data\vector.shp D:\data\raster.tif') However it returns this error message: 'qgis' is not ...
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2answers
89 views

Python Error in QGIS Ubuntu 13.10 while trying to join .csv tables

Using the mqgis plugging in QGIS I cant join my csv file... This is what QGIS returns me: An error has occured while executing Python code: Traceback (most recent call last): File ...
1
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1answer
103 views

Clip raster with shapefile

I want to clipping raster (Lidar) with shapefile in qgis ver.2.0.1. Which plugin in qgis could I use it ? Thanks for help me.
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0answers
101 views

Google Maps basemap not showing up when KML file added as a vector layer in QGIS - only point markers appear

I am trying to make a basic XYZ contour plot in QGIS 1.8.0 (longitude, latitude, depth in an excel file) and can't get past the first step of adding a basemap in QGIS. I've tried using the Open ...
0
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0answers
89 views

Invert axis orientation in QGIS

I'm loading two WMS layers served from GeoServer with declared srs EPSG:4326 in QGIS 2.0 in EPSG:4326. The two layers displays correctly when I zoom in to Sweden. If I display the two layers in ...
3
votes
1answer
392 views

How to set up a Web Map Service with QGIS?

I am very new to QGIS environment.I wanted to work with creating Web Map Service using QGIS server.Does it possible to create Web Map Service in QGIS sever? can anybody help me with resource link and ...
1
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1answer
43 views

When I save a project to a folder, I get this error message

I opened QGIS, started a new project, and loaded rasters. Then I saved the project to a folder I had already created. I got the following error message. The same exact message appeared when I closed ...
1
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1answer
41 views

Rough edges on tiles in QGIS

I'm loading four .ASC files into QGIS, each containing topographical data about a tile of 10 x 10 km. On the map, this data is displayed as black/white and different shades of gray. My problem is that ...
1
vote
1answer
79 views

Retrieving lost data from QGIS

I'm trying to help a friend retrieving QGIS data from a formatted drive. Finding the .qgs project that was saved on the desktop is no problem, but it seems that there is no actual data located in ...
2
votes
0answers
125 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
1answer
120 views

Trying to set NAD 1983 EPSG 102631 in QGIS

I was able to find the right coordinate system online NAD 1983 Alaska But now I don't know what to do. I can't find the coordinate system on QGIS. When I choose the one I think is correct it warps ...
1
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0answers
137 views

How to improve creating contours for super-high unnatural mountains?

in a current project I am working on we are not mapping the actual height of a landscape rather mapping the interest which specific stakeholders have in parts of the region. So, what we did was the ...
3
votes
1answer
209 views

How do you export to georeferenced PDF from QGIS 2.0?

When I use the print composer in QGIS, there is no option to export to georeferenced PDF using GDAL. Do I need to export from somewhere else or how do I go about exporting to georeferenced PDF? I am ...
4
votes
3answers
2k views

3D visualisation with open source GIS software [closed]

I'm searching for QGIS (or other open source GIS software) tools that can analyse XYZ data. Also I'm interested to hear about if anyone have migrated to non commercial software regarding geological ...
0
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0answers
30 views

qgis python plugin enabling other plugins

maybe it is a stupid question but i am new in qgis. I developed some python plugins and they work correctly, now what i would like to do is to install a "door" plugin that after asked ...
5
votes
1answer
1k views

QGIS and SQL Server Spatial Tables Performance

I'm trying to get a SQL Server 2008 R2 spatial database up and running to streamline the production of maps using QGIS. Currently I just have a handful of spatial tables (a postcode level point table ...
1
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0answers
135 views

QGIS: How to reverse vertex ordering in polygons

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
4
votes
1answer
195 views

How to find a single point furthest from any road?

I have a road layer of a country. What method or plugin would you suggest, to find a single point furthest from any road (but as you can see, there is a coastline, so points in the sea can't count) ...
1
vote
1answer
176 views

How to add the current document path on Print Composer?

I'm trying to demonstrate to my company that we can begin using QGIS in conjunction with (and sometimes even instead of) ArcGIS and MapInfo. I've started setting up some layout templates but have run ...
2
votes
1answer
172 views

How to synchronize the marker's rotation field with the angular distortion in the map projection

I'm Using QGIS 1.8.0 to plot a global dataset showing the positions of aircraft in flight. The data I have are .csv files with three columns: Latitude, Longitude, and angle of travel. I assign ...
0
votes
2answers
50 views

Change precision of Real column

I have a sqllite table which has columns to hold the hectares and acres of polygons but I only want to have two digits after the decimal point - when calculated they have 14! How do I change this so ...
2
votes
1answer
294 views

Thematic map with points QGIS

I would like know how can I make a thematic map (soybean production) with density points. In this case the points are randomly plotted in a municipality area. Please, see an example in the image:
0
votes
1answer
832 views

How to resolve Geoserver ERROR: Operation on two geometries with different SRIDs

I am working on Geoserver Version 2.4.2 . I have one layer 'beat' in postgresql database. I have publish layer in geoserver but its not opening OpenLayers layer preview link. It gives error as ...
0
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0answers
41 views

Why legendLayerActions is not available in QgsLegendInterface

There's a reason why QgsLegendInterface (the python interface to QgsLegend) doesn't expose: QList< LegendLayerAction > QgsLegend::legendLayerActions( QgsMapLayer::LayerType type ) const method? ...
1
vote
1answer
452 views

How to clip an Openlayers OSM Background to a Vector Boundary?

I'm new to QGIS. In my project i have two layers: one is my vector (city boundaries) and the other is the OSM (obtained with the plugin). How can I cut the OSM along the edges of the vector? I want to ...
1
vote
1answer
297 views

QGIS hillshade error “GDAL provider: Cannot open GDAL dataset ”

I am using a DEM and using menu Raster > Terrain analysis > Hillshade. When I type a simple output file name "MyHillshade" and then click "OK", I get a two-part error message that says: "GDAL ...
1
vote
1answer
93 views

Which File to load from National Hydrography Dataset?

Start-over beginner here. I'm using QGIS 2.0 on MacBook with OS X 10.8.5. I downloaded a National Hydrography Database file. Unzipped, it is titled NHD11032_NM.gdb. I try to add the layer as a vector ...
1
vote
0answers
69 views

How to run PostgreSQL stored procedures from QGIS? [closed]

I'm trying to figure out if it's possible to run a stored procedure in a Postgres database from QGIS, more specifically I would like to do this from within a python plugin. In this case I'm trying to ...
1
vote
2answers
430 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 ...
2
votes
2answers
246 views

How to use ggplot with Processing in QGIS 2.0?

I'm trying to use R scripts within QGIS thanks to Processing. There are some example scripts available and I achieved to plots different columns of the attribute table (with the plot built-in ...
0
votes
0answers
52 views

How can I add/define a legend for RGB images in QGIS?

I have a RGB image in QGIS that is the product of some raster analysis (e.g. QGIS's relief operation, results from sound/traffic models) to which I want to add a legend. I'd like to denote several RGB ...
0
votes
0answers
98 views

Can I simplify polygons in QGIS by Size?

Just wondering if it's possible in QGIS to simplify polygons based on size? I've done it many times using the tolerance level to reduce the overall size however in this case each polygon cannot be ...
0
votes
1answer
57 views

Raster to Surface

I have a raster and I have been asked to modify some pixel values in it. Is there an open source way to do this? I would guess that I have to create a 3d surface, then manipulate the surface, then ...
3
votes
1answer
390 views

How to build a confusion matrix for image classification using SAGA or QGIS?

I did a supervised classification of a Landsat image subset using my training data polygons. I used SAGA GIS for that and everything worked out fine. Now I am stuck since I have no clue how to ...
2
votes
3answers
140 views

Generating a polygon tile index from multiple vector datasets

OK. well this is silly, in that there is no way it should be as difficult as it has been for me to find information regarding how to generate a polygon tile index from multiple vector (contour) tiles. ...