Tagged Questions

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

learn more… | top users | synonyms (1)

1
vote
1answer
240 views

How to add MS SQL table using python console?

I have MS SQL Server 2008 R2 database. How to add MS SQL Table using python console in QGIS?
2
votes
1answer
220 views

Cannot find my schemas in QGIS's “Add PostGIS layers”

When I connect to my PostGIS database using QGIS's Add PostGIS Layers, I see only public topology pg_catalog information_schema My other schemas that I have created are not shown here. Anyone else ...
2
votes
0answers
109 views

Storing features in PostGIS and then creating layers using queries

I have a whole set of line segments or tracks that represent real tracks or, in some case, boundaries between areas. These segments form a network of lines on the map. I have a number of GIS layers, ...
3
votes
3answers
244 views

Can one load multiple GPX files at once?

I have a whole bunch of GPX files that I need to load into qgis and loading them one at a time using the GPS plugin is a bit painful. It will not allow one to select multiple files -- is there ...
2
votes
1answer
108 views

Join attributes by date in Qgis

I learned (thanks!) to use the join feature built into the layer properties, but in my case it doesn't work because data do not match perfectly. Infact shape refers to geotagged photos, csv is a log ...
1
vote
0answers
192 views

How can I move two layers at once in QGIS?

I'm trying to move two digitized layers, one containing points, the other polygons to a different location at the same time. QGIS doens't seem to allow this. Even if I select both layers and features ...
1
vote
1answer
74 views

How do I get a decent easy to use watermark from an image in Quantum?

Our users need to be able to put a graphic watermark onto maps they create in the print composer. Currently we get them to georeference the image as a raster and then create a transparency. This is ...
0
votes
1answer
410 views

qgis plugin: “WindowsError: [Error 6] The handle is invalid”

OS: Windows 7 64bit GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe) path variable: GISBASE=C:\Program Files (x86)\Quantum GIS Lisboa\apps\grass\grass-6.4.3RC2 ...
0
votes
1answer
413 views

Problems using v.split in SEXTANTE toolbox to split lines

I got this error: Or don't click "open output file after running algorithm", but there is no new shapefile created on my desktop. How to solve this problem and split lines at a specified distance? ...
0
votes
1answer
237 views

Using the API of QSpatiaLite plugin

I am using the popular QSpatiaLite plugin for QGIS. Since I am creating and modifying SpatiaLite tables directly with Python (using pyspatialite), I wonder whether I can automate tasks such as ...
1
vote
1answer
187 views

How to set the path to shapely?

I am using QGIS 1.8.0 on Mac OS 10.8.3 with python 2.7. Thanks to other threads in the forum, I have successfully installed shapely here: ...
3
votes
1answer
880 views

How to split line at a specified distance and getting coordinates of start and end points of each line segment?

I tried v.split in GRASS: and my notebook ran a lot of time but showed this error:bad allocation, then I click "OK", and got nothing. Are there other ways to split lines?and I hope to get 2 new ...
1
vote
1answer
52 views

Is there a way to traverse and select all vectors connected to a starting vector?

Preferably using QGis I'd like to remove errors from a road network .shp file and was wondering if there was a away to perform a flood fill or traversal on a vector layer to select all connected ...
4
votes
1answer
843 views

Why does Google satellite layer change the project CRS?

I have a project and a topomap in WGS84 (EPSG4326). On the fly CRS transformation is activated. I open Google satellite layer from the OpenLayers plugin. The Google layer is WGS84 / Pseudo Mercator ...
1
vote
1answer
457 views

import grass.script as grass under windows 7

OS: Windows 7 64bit GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe) I have created a plugin for QGIS, with the QGIS plugin builder. Now i would like to import grass.script into ...
2
votes
1answer
40 views

Is it possible to always see all band values with Identify Features?

Does anyone know if it is possible to get the Identify Features tool in QGIS to show the band values for all the layers shown in the results window? To clarify, whilst I have several bands "showing" ...
0
votes
0answers
123 views

How to join edge of International Date Line in world file?

I am currently using world file (http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html) for international boundary information. Now I have difficulty with map projection that the map ends with ...
1
vote
1answer
67 views

How to identify to which polygon a point belongs to?

I have 3-4 polygons containing lots of lon/lat points. I want to identify to which polygon a specific point belongs. Any help in this matter is appreciated.
1
vote
0answers
162 views

How to fix “Error processing specified tolerance!” in Polygon Centroids tool?

I am using QGIS 1.8.0 to find the centroids of 92 features (i.e. smaller polygons) in a polygon layer. However, while using (Vector -> Geometry Tools -> Polygon centroids), I encountered the ...
0
votes
3answers
347 views

clipping polygons (vector) map with a polygon (vector) layer

A frustrated newbie with QGIS Lisboa version in Windows 7. I want to clip a soil map (multiple polygon vectors) with a single polygon (rectangular polygon vector). The project projection is set at ...
1
vote
0answers
405 views

GRASS Plugin to QGIS error

I am installing QGIS and GRASS as part of an FOSS GIS class I'll be teaching this summer. I used the OsGeo4W installer. This installer has always worked flawlessly for me except on the machines at the ...
1
vote
1answer
373 views

Problem to clip a raster with a shapefile

I need to clip a rasterlayer with a vector layer. When I try this, the following error appears: **ERROR 1: Attempt to create 0x0 dataset is illegal,sizes must be larger than zero.** What am I ...
2
votes
2answers
234 views

Data points Imported into QGIS are in the middle of ocean

I'm new to QGIS and tried importing some GTFS data in the CSV format (stops.txt). The project CRS, base map CRS and GTFS CRS have all been set to Google Mercator, but the points that are supposed to ...
1
vote
1answer
774 views

How to create a 3D shapefile from a raster?

I´m trying to make a 3D shapefile from a raster feature but not working. Tried already to run the command in OSGeo4W but nothing happen. I'm using the Qgis 1.8.0 Lisboa. The purpose is to get a final ...
1
vote
2answers
168 views

How to handle adding a PostGIS layer in pyQgis without saving password?

I'm writing python plugin and trying to find the right way to add PostGIS layer on the map without storing user password. After adding layer on the map, I strip out the password from uri like this: ...
8
votes
1answer
445 views

How to address the new “Task-Completed” QgsMessageBar in Python?

I am really amazed what huge steps the QGIS development has taken in the last months. The new iconset, the improved Print composer and many more changes to be seen in QGIS 2.0 are really awesome! ...
1
vote
1answer
702 views

QGIS - Save as GPX [duplicate]

I would like to convert .shp into .gpx. I tried to "save as" gpx but it gives an OGR error: creation of field ObjectId failed (OGR error: Field of name 'Name' is not supported in GPX schema. Use ...
1
vote
1answer
198 views

How to enable label orientation?

Mac OSX 10.6.8 QGIS 1.8.0 : I'm mapping an area that's a rectangle slanted at 26 degrees, and neighbourhood maps are always printed so the rectangle is horizontal. I'm trying to make the labels ...
1
vote
1answer
97 views

Vector Layers are not lining up and are scaled differently

Hey I am a first time user of GIS and I am working for a transportation map of North Carolina for a project at my work. So what I have been doing is first placing the Tiger County Boundary by using ...
2
votes
1answer
98 views

With multi-line labels, how to show the 2nd line only for labels that need it?

Mac OSX 10.6.8 QGIS 1.8.0 : I've two columns in the attribute table, name, and name2 for those labels that need to be 2 lines; multiline labelling is checked. But when I use "name"||'\n'||"name2" I ...
3
votes
2answers
384 views

QGIS Field Calculator Results Removed When Saving Edits

Mac OSX 10.6.8 QGIS 1.8.0 : Using the field calculator from the attribute table, the $area of each feature is shown nicely in the table until I try to save it, then all the values are replaced by NULL ...
0
votes
1answer
78 views

Why can't I see any joined string fields for categorization?

After the join I can see all my data in the attributes of the card but when I want to select statistics in the tab style to categorize, I don't see them. I see that the real type variables and not ...
1
vote
0answers
39 views

Do I need to deal with warnings about row count and spatial index to use pgRouting?

After read this nice post from underdark A Beginner’s Guide to pgRouting, although I still have some little problems, I think I can begin the "Creating a routable road network" stage right now. I got ...
2
votes
1answer
362 views

How to add one or more points to an existing polyline or polygon?

Using the following code, I make a polyline with two points. vl = QgsVectorLayer("LineString", layerName, "memory") pr = vl.dataProvider() vl.startEditing() fet = QgsFeature() ...
0
votes
0answers
211 views

Compilation of QGIS master branch under CentOS 6.3

I tried to compile QGIS master branch 1.9 (qgis-Quantum-GIS-b99ff61) under CentOS for many hours now as explained here and here / here Compilation: [ 7%] Generating ui_qgsmapserverexportbase.py ...
2
votes
1answer
111 views

How to check if two qgsPoints are equal in PyQgis

I have two points: a=QgsGeometry.fromPoint(QgsPoint(227739,908343)) b=QgsGeometry.fromPoint(QgsPoint(227739,908343)) but when I run: a==b it returns False. What am I doing wrong? Update: it ...
1
vote
1answer
676 views

QGIS python location problem

It seems that MacPorts installs Python27 in /opt/local, but that MacPorts QGIS updates and uses the Apple Python27 in /Library. The result is that MacPorts additions to Python27 such as OpenCV don't ...
1
vote
1answer
132 views

How to save after using fet.setFeatureId in pyQGIS?

By using the following code, I want to change the id of the line when saving the line. But the setFeatureId command, gives a false when doing the commitChanges(). Any idea how to change the id? vl = ...
3
votes
2answers
228 views

How to write an equivalent to MapBasic's CreateLine in pyQGIS?

I know this kind of question has been asked, in part, before - specifically: Seeing QGIS Python Commands and: How is object created as line using createline stored in .tab file? but this is a specific ...
1
vote
1answer
363 views

How to store selected attributes of vector layer using PyQGIS

I'm following this PyQgis workshop: http://www.qgisworkshop.org/html/workshop/python_in_qgis_tutorial2.html#accessing-data-attributes I have a point layer shapefile. I want to be able to retrieve and ...
1
vote
3answers
732 views

export 3D data dxf file

I'm trying to export a DXF file from Qgis1.8.0 Lisboa and can not have a 3Dfile in Autocad! Or micristation. It results always in 2D file. How can I export height data from a shape file in Qgis? ...
3
votes
1answer
452 views

Varying Line Widths According to Attribute Values

I'm trying to draw a vector map of Europe on QGIS 1.7.3 with lines symbolizing the transmission of energy (power transmission lines) between the different countries on the map. I am trying to ...
0
votes
0answers
93 views

'D8 Slope Grid' in Sextante-QGIS is not working

I can't make 'D8 Slope Grid' work in QGIS-Sextante. 'Pit Filled' and 'D8 Flow Direction Grid' output work okay. I used the function: Geoalgorithms > Uncategorized > Basic Grid Analysis tools > D8 ...
0
votes
2answers
2k views

How to convert Shapefiles to 3D DXF?

I'm using QGIS version 1.8.0-Lisboa and I'm trying to convert a vector line file and it's not working. I right click on the layer>Save as>Autocad file>DXF. After that I try to open the output file in ...
0
votes
1answer
118 views

problems about setting pgrouting with QGIS under windows

I followed this website:A Beginner’s Guide to pgRouting and now facing some problems. I finished steps before "Creating a routable road network", and open QGIS 1.8, click the PostGIS Manager plugin, ...
0
votes
0answers
51 views

Problem with compilation

I have tried to compile Quantum GIS by it's source code on Windows 7 (32 bit).i have follow it's installation guide.i have download and install all it's dependencies . i have run it on C-Make but it ...
2
votes
2answers
184 views

How to create a line from more than two points?

I have a loop which calculates two points for each iteration (x3,y3) and (x4,y4). As seen in the code these two points are added for each iteration, which gives i-1 lines. Each line has a individual ...
2
votes
2answers
458 views

Flow modeling and FOSS GIS; lahars and HEC-RAS

What are the options for FOSS flow modeling of dilute debris flows in QGIS or GRASS? Have you, or can you refer me to studies where the authors, tested these models/plugins/functions/etc. for use in ...
1
vote
0answers
446 views

How to calculate weighted mean coordinates within polygons?

I'm using QGIS 1.8 on OSX 10.8.3. I have a polygon shapefile of all of the US state legislative districts. I also have a layer of points that are centroids of US Census Tracts, with a field for the ...
1
vote
1answer
800 views

Multiple reclassification using RasterCalc in QGIS [duplicate]

Is there any way to perform multiple reclassification using RasterCalc? For example reclassifying value 1 to 100 in map Map can be written as: eq([Map]@1, 1, 100) But if there are multiple values ...