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

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2
votes
1answer
190 views

How to calculate correct angles for lat/lon points with the QGIS API?

I am trying to use qgis API to calculate the angle between two points by using function azimuth of class QgsPoint ( http://qgis.osgeo.org/api/classQgsPoint.html ), and my CRS is EPSG:4326 - WGS 84 , ...
2
votes
3answers
412 views

Why are some points in my PostGIS layer not displayed?

I have PostGIS table with some points and various attributes. Yesterday I added some more points to the table and now weird things are happening when I try and display layers built from these points. ...
2
votes
1answer
97 views

How to remove/disable last row/column of SRTM GeoTIFF in QGIS?

I've started using QGIS yesterday, and one of my main reasons to use it is to apply colormapped SRTM v4 over Google aerial imagery. Everything is working fine, except that SRTM v4 elevation tiles ...
4
votes
1answer
748 views

Why is tiff different in epsg 3857 and epsg 900913 in gdal

When I transform tiff from 4326 to 3857 and from 4326 to 900913 in gdal, I get different result(when display in Qgis) eventhough these two projections(3857 and 900913) should be the same. What is ...
3
votes
2answers
360 views

How to handle PostgreSql 1:m relationship data by using “Data-Driven Input Mask” QGIS plugin?

I have 1:m relationship tables in my PostgreSql. I like to show the main table attributes as well as the relational table attributes (like grid rows) in QGIS attribute-edit-form. What are the entries ...
0
votes
1answer
376 views

Field Calculator returning incorrect length and area values when QGIS project is reopened

Similar to Field Calculator returning incorrect length and area values, but as always slightly different. I have QGIS 2.0 and when I create a polyline shapefile, the field calculator returns the ...
7
votes
3answers
2k views

What format and settings to use for aerials photos in QGIS?

Following question which was more about handling Aerials with ArcGIS: Most Effective Format to Manage Aerial Photography for Viewing Only It seems there are 2 major options for storing / resampling ...
1
vote
1answer
441 views

How to use MOLUSCE plugin in QGIS?

I am trying to explore MOLUSCE ver 3.0.4 in QGIS Dufour. I am trying to simulate the land use change using this tool. I have following querries: It asks for Initial and final year at the first step. ...
6
votes
3answers
4k views

Simplifying adjacent polygons using QGIS “Simplify Geometries” tool

I have a big Shape file with 200,000 polygons but the file is too big for the application that will use it. I would like to generalise these polygons and create much smaller file. I have tried to do ...
0
votes
2answers
626 views

How to draw line pointing in compass bearing direction from point shapefile? [duplicate]

I captured waypoint data in the field including the compass azimuth when looking at some summits. I want to use these waypoints, that I have now in Shapefile format, to draw line shapefiles that ...
2
votes
1answer
452 views

How to use “Data-Driven Input Mask” QGIS plugin?

I have installed Data-Driven Input Mask plugin in QGIS and added necessary relationships between PostgreSql tables. But I don't find any changes in the UI. How to enable/configure this plugin ...
0
votes
1answer
3k views

How to use GRASS module to delineate watershed area?

Update#1:I changed to work under qgis 1.8, I only input the DEM file and run the r.watershed module, and I got this: I have a DEM file of one specified region, and I take the following steps to ...
5
votes
1answer
478 views

How to convert ArcMap color ramps to QGIS?

I have both ArcGIS 10.0 and QGIS 2.0 How can I reproduce a specific ArcGIS color ramp in QGIS? If possible, I would like to simply convert the Esri *.style file but perhaps there is another ...
1
vote
1answer
117 views

How to read the count of the cells with data with non “no-data” values ,in QGis?

How to read the count of the cells with data with non "no-data" values ,in QGis
3
votes
1answer
809 views

How to convert a CSV from DMS to WGS84 in QGIS?

I would like to automatically convert from a Degree - minute - second system to WGS84 EPSG:32632. I have a CSV with these kind of values: LATITUDINE LONGITUDINE 46°01’24,7” 11°13’47,5” 45°42’07,5” ...
3
votes
2answers
665 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 ...
1
vote
2answers
1k views

Trying to use a QGIS plugin - getting classFactory error

I've had to create a GIS for the company I work for, choosing QGIS over ArcGIS due to price (company doesn't want to buy another copy of ArcMap). In any case, it's not a HUGE GIS but it would be good ...
5
votes
3answers
189 views

How to label only some places instead of all?

How do I turn of some place names, or rather turn on some places names but not the rest. How do I turn of or hide that? [s]I also get a red cross under the place names which I dont like to see. How do ...
1
vote
1answer
192 views

How do i install QGIS with FileGDB?

Please help me i am very new at this and the last time I asked i was sent to a link about an older version of QGIS. I need to know how to install QGIS 2.0.1 for Windows 8 64 bit so it can recognize ...
1
vote
1answer
87 views

QGIS Grid Division/Grid Product etc. results are wrong projection

I have several raster grids, all 4320 columns, 2160 rows in WGS 84 projection. They are loaded from ESRI ascii files. When I use the Processing Toolbox to carry out arithmetical transformations on the ...
2
votes
2answers
1k views

Unable to load 'nviz' through GRASS

I am using QGIS 2.0.1-Dufouron on Windows 7. When I try to load nviz via GRASS, I get the message "Module nviz not found". Weirdly enough, I can load it via the toolbox and be able to 'run' it (it ...
2
votes
2answers
806 views

Can I achieve one-to-many relationship in QGIS custom forms?

My PostgreSQL database has ElectricLine geometry table which has one-to-many relationship with ElectricLineMaterial non-geometry (attribute only) table. This PostgreSQL table added as layer in QGIS ...
4
votes
2answers
3k views

Multiple labels in QGIS [duplicate]

Is it possible to show 2 or more labels for 1 layer? For example - 1 label will show the name of a school and the 2nd label will show the number of students? They should be completly different labels. ...
3
votes
2answers
314 views

How to (image) capture map and copy it to clipboard using QGIS?

Essentially, I want to copy a map to clipboard (not Save as Image).
2
votes
2answers
169 views

How do I set a CRS when it isn't listed in QGIS? (Mac, not PC)

I want to work with a shapefile that is in a Coordinate System that I can't locate in QGIS for Mac. When I load this shapefile data, it shows up fine, on-the-fly has generated the CRS data most likely ...
3
votes
2answers
2k views

Set feature attribute by name via QGIS python api

I try to set feature attributes by attribute name with this code pr = layer.dataProvider() pr.addAttributes([QgsField("test", QVariant.Int)]) layer.updateFields() for feature in layer.getFeatures(): ...
2
votes
1answer
363 views

Open Layers and OSGB 1936 (CRS 27700)

I've been working with loads of shapefiles projected according to OSGB 1936 (CRS 27700). THe project CRS is set to 27700 and "On the fly reprojection" to 27700 is set (I keep this as a default as I ...
1
vote
1answer
98 views

How to set symbology type and color based on data?

I have a point vector layer with several attributes in QGIS Dufour. One of them is satellite name, and the other is date. I want to display different dates with different colors (using some gradient) ...
2
votes
1answer
489 views

How to find neighbouring polygons with same attribute value?

I have certain amount of polygons with different classes (numbers). I would like select/find all these polygons that have a neighbor-polygon with the same class. Is there a tool in QGIS, ArcGIS ...
2
votes
2answers
399 views

Can I use QGIS 2.0.1 with the National Hydrography Dataset (NHD)? [closed]

I'm a trying to learn QGIS. I am trying to download and open with QGIS state-specific data from the USGS NHD Viewer, and i think i have at least managed to do the downloading correctly. For example, ...
1
vote
1answer
1k views

Create cross section with polygon intersects in QGIS [duplicate]

Is it possible to create a cross section that shows the intersected polygons on the relief (in QGIS 2.0.1)? I would like to try this out for a geologic map. I'm using VoGisProfilTool: ...
2
votes
0answers
74 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 ...
0
votes
1answer
58 views

Calculate best area with overlaying multiple layers buffer shapes

I am using QGis and I have a set of 20 layers with buffers. I'm interested in where they overlap most and I want to create a single layer that shows which are the places where they overlap most and ...
2
votes
1answer
61 views

Installing Demo Datasets

I installed QGIS without selecting the demo datasets. Now I realise that was a mistake. Is there a way to install these after QGIS installation or do I have to uninstall completely and re-install? ...
0
votes
1answer
182 views

How can we split a polygon within another polygon in Qgis? [duplicate]

How can I split the green area as a separate polygon fro the grey one in QGIS?
0
votes
1answer
132 views

Graduated colouring Voronoi polygons? (QGis)

I've got a huge database of depth points for the whole Irish sea which I'd like to be a nice smooth surface, or at least have a depth value associated with the entire area (i.e. include the ...
2
votes
0answers
32 views

How to save complex expressions in QGIS Field Calculator? [duplicate]

I have been debugging some long case expressions in the field calculator and getting frustrated because I have to remember to copy the expression before I test it otherwise I end up having to reenter ...
3
votes
1answer
85 views

Do pad functions of QGIS Field Calculator have bug?

I have this expression in the field calculator: regexp_replace('1', '^(\\d+)', rpad('\\1', 3, '0') ) gives 01 rather than 001 as expected. the *pad functions work fine when called outside ...
1
vote
2answers
115 views

How can I do more flexible matching in conditional expressions than provided by LIKE?

With LIKE '%' works but I have had no luck with character ranges, i.e. [0-9] to match a digit. Oh for a regular expression ;)
2
votes
1answer
90 views

Can QGIS save layer direct to PostGIS?

I see that there is no option in the layer->save as menu for saving to a postgis database. There are for both SpatiaLite and SQLite. I am guessing that the interface to PostGIS is significantly more ...
4
votes
1answer
227 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 ...
11
votes
9answers
9k views

Open Source equivalent to Collector for ArcGIS to use with QGIS/PostGIS?

From my reading of the Esri web pages the Collector for ArcGIS is tightly tied to that platform. I would be delighted to learn that I am wrong about this. I have a strong interest in generic mobile ...
3
votes
1answer
272 views

How to programmatically add an algorithm from external plugin to QGIS processing toolbox?

I'm writing a python plugin for QGIS and I'd like to know if it's possible to provide an interface to it from the processing toolbox. I can see how the existing algorithms are loaded into processing ...
5
votes
1answer
1k views

How to extract pixel value counts from a raster in QGIS?

How does one go about obtaining a summary of the counts of cell values within a raster in QGIS? I know QGIS is doing this, in order to provide the summary statistics and histogram in the properties of ...
2
votes
2answers
967 views

Does QGIS attribute edit form support “relationship” data?

Consider I have a geometry table having one-to-many relationship with a no-geometry table. When I create a feature (geometry), I would like to be able to add the relative no-geometry table data in the ...
3
votes
4answers
942 views

Esri File GDB multi-user edit through QGIS

I have an Esri File GDB with relationship classes. I would like to import this GDB in PostgreSQL or MSSQL to enable multi-user edit through QGIS (dufour) tool. What are the steps/procedures to ...
1
vote
1answer
165 views

Is there a bug in Georeferencing in QGIS 2.0?

I recently updated to QGIS 2.0. But now, when I need to georeference some pictures, I have serious problems. When loading the files to be georeferenced, I can see only a part of it in the window, so ...
2
votes
1answer
552 views

How to format labels with leading zeroes?

I'm trying to display a number next to a symbol in QGIS 2.0.1 - The numbers are from an integer-field in a postgresql database. The goal is that single digit numbers get a leading 0. Examples: 12 ...
1
vote
2answers
343 views

Georeferencer plugin will not load in QGIS

I have downloaded and installed QGIS. I would like to georeference an image using the core georeference plugin. When loading it no toolbar appears and the 'update', 'reinstall' etc boxes in plugin ...
0
votes
0answers
104 views

Export additional data with ogr2ogr

I am trying to import my ESRI-shapefile with OGR2OGR to an existing mysql table. This works fine but unfortunately only the featureID and the geometry data is exported. How do I add the labels of the ...