Tagged Questions

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

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3
votes
2answers
225 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
352 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
661 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
427 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
90 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
117 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
182 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
445 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
413 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
748 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 ...
0
votes
1answer
563 views

How to clip raster by multiple polygons in multi rasters?

Using QGIS, I want to clip a raster by multiple polygons contained in a single shapefile. I read that gdalwarp can clip my raster by multiple polygons BUT the output is a single merged clipped raster. ...
3
votes
2answers
206 views

Is there a way to call the clip function in pyQGIS from the python console?

Is there a way to call the clip function in QQGIS from the python console? It is found under geoprocessing tools in the vector menu.
2
votes
2answers
966 views

How to add a column in QGIS via python

I have a point shapefile and a polygon shapefile in QGIS now I want to use the point shapefile's value add to polygon shapfile(be a column in the end) there are colors with each value and make the ...
0
votes
2answers
125 views

Manually add a new point to PostGIS table [duplicate]

I did accidently delete a table row - or well, in fact a whole subway station. My attempt to solve the problem was this PostGIS function: ST_GeomFromText('POINT(coordinates)') But then PostgreSQL ...
3
votes
1answer
119 views

Differences in raster extents in gdalinfo, SAGA & Quantum after resampling

I recently resampled a raster file using SAGA's Resampling module. The aim was to widen the extent of the new raster to two decimal places, where the original raster has three decimal places. The ...
2
votes
2answers
336 views

What's the correct transformation for Lambert Conformal Conic for Wyoming?

I am a newb in QGIS. I have loaded QGIS 1.8 (Lisboa) and practicing with a number of maps for portions of the state of Wyoming. My maps are mostly in UTM 12N NAD 27 & NAD 83 some are in decimal ...
0
votes
1answer
302 views

matching a border of one polygon to another [duplicate]

I have a polygon (A) that I drew the eastern border of in QGIS. I have another polygon(B) whose western border I want to nest against the eastern border of polygon a so they are touching but not ...
1
vote
2answers
186 views

Problem with reprojecting raster from MGI 6 to WGS

When I reproject a raster from Mgi 6 to WGS 84 using Warp in Quantum gis it makes mistake ( about 380m). Is there any way to avoid this?
4
votes
2answers
237 views

Autocorrelated DEM with QGIS or Grass

I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
4
votes
2answers
1k views

QGIS Server limitations?

QGIS Server seems to be fairly simple to setup and create services, however I'm wondering if there are any limitations with using it opposed to MapServer or GeoServer. My current server ...
2
votes
2answers
892 views

Reducing the resolution of a huge raster

I'm not much of a GIS user, but I've got a big ascii file that I'm trying to convert into a lat long data x1 y1 d1 x1 y2 d2 x1 y3 d3 x2 y1 d4 ... etc format, so that I ...
13
votes
5answers
1k views

Where to start learning how to make maps with QGIS?

I have no skills in GIS, "map-making," or any other map program. Been a county planner for 25 yrs, where there was always a "drafting" staff. I'm in another agency now and need to be able to produce ...
3
votes
1answer
355 views

How to calculate all paired shortest path using PyQGIS?

The code for shortest path analysis with PyQGIS specifies start and end nodes explicitly: pStart = QgsPoint( -1.37144, 0.543836 ) pStop = QgsPoint( -1.1027, 0.699986 ) ...
1
vote
0answers
133 views

Event Layer plugin - setting/verifying z coordinate (Measure attribute)

I've loaded a shp file (ROUTES.shp) layer containing geometry for highway segments with a ROUTE attribute for each. I understand that the plugin uses the "z" coordinate of the shp file segments to ...
0
votes
1answer
414 views

How to label each polygon in a layer?

QGIS 1.8.0 Mac OS 10.6.8: I want to label each polygon in a layer in a similar way to this image (done in WP Presentations) and am totally confused by the manual. Obviously I have to find a list of ...
1
vote
1answer
146 views

Modify CRS to match boundaries of shapefile

I have boundary data in WGS'84 lat/long and data in a custom generated CRS. The data in the generated CRS appears to be offset by a particular vector compared to WGS'84. I want to attempt to match the ...
2
votes
1answer
320 views

How to join nodes to network lines ( and not the other points)

I'm trying to do a shortest path analysis on my network. In order to prepare the network and attach polygon centroids to the roads, I used GRASS' V.NET operation=connect. the problem with this ...
1
vote
1answer
151 views

plot path of points

I have a sample of the address histories of households. ID ZIP1 ZIP2 ZIP3 01 XXXXX XXXXX XXXXX 02 XXXXX XXXXX XXXXX 03 XXXXX XXXXX XXXXX 04 XXXXX XXXXX XXXXX ... It's easy enough ...
3
votes
1answer
1k views

How does Flow Mapper Plugin work?

I downloaded the Flowmapper plugin for Qgis and I can't seem to find any information on how it is supposed to work... Also the text seems to cut-off and not fully showing for the input fields so I'm ...
0
votes
1answer
148 views

Problem with encoding of CSV and SHP files in Linux

I am new to using QGIS. I came up against the encoding issue of shp files. This solution to solved my problem in Windows (for source I had to put windows-1253 instead of utf-8) My question is what ...
1
vote
0answers
288 views

intersect two shape files using QGIS API

I am trying to automate a process of a shape file. We are using google maps engine and we have limitation on number vertices in a shape file. so I am using a grid to split the shape files. In GUI , I ...
1
vote
1answer
348 views

How to get vector feature by mouse location?

I'm writing a photo grouping plugin. My current problem can be broken up into "end goal" and "baby steps", because I think that's what I want. But if there's a way to get to the end by a different ...
1
vote
2answers
585 views

Problem with WMS layer from SAGIS: Invalid format/can't parse XML

Can you help me the following problem: I try to load WMS layer from SAGIS (Salzburg GIS) into Qgis: http://www.salzburg.gv.at/themen/se/sagis/download.htm for example: Geoland WMS ...
3
votes
1answer
1k views

How to handle “Mount: Access Denied” when installing QGIS on Win7?

I tried to install qgis on my laptop with Windows 7 Professional and it is a 64 bit machine. after going through the procedure described below I got the message "Mount Access Denied". What is going ...
1
vote
1answer
206 views

How do you parse an HTML formatted attribute value to seperate columns in a database table?

All, I have an attribute field formatted using HTML all ready to go for google earth markers. The KML in question is here: http://dl.dropbox.com/u/95231813/state_pts_MI.kml Here is the value: ...
1
vote
1answer
143 views

How to add another layer origin in my installed OpenLayers plugin?

Can I modify my installed Openlayers plugin files to add a new layers origin? If yes, what files?
1
vote
1answer
983 views

QGIS can't find osgeo after GDAL upgrade

Mac OS 10.6.8: I installed QGIS 1.8.0 with GDAL 1.8; then another app requires GDAL 1.9 and installed it; now QGIS can't find osgeo [python-gdal]. (I can't find any trace of GDAL 1.8 left in my ...
3
votes
1answer
135 views

How to create a small globe locator map in QGIS?

I've tried searching on gis.stackexchange and elsewhere but can't seem to figure this one out though it seems simple enough. The type of locator I'm thinking of is similar to the one from the map in ...
7
votes
6answers
2k views

Unable to connect Postgis from QGIS 1.8.0

I have installed PostgreSQL and PostGIS on my laptop (Win 7 64 bit OS). I am running QGIS 1.8.0 on my machine . When I am trying to connect Postgis I am getting connection failed error then I tried ...
1
vote
0answers
88 views

How to randomize colors for large datasets in QGIS new symbology?

Someone has already asked how to randomize colors by class in QGIS new symbology, but the answer there does not work with datasets containing more than 100 unique values since the Random option only ...
1
vote
1answer
124 views

Is it possible to fix a vector layer after I badly georeferenced a map? [duplicate]

Sorry in advance if I missed another question on this topic. I searched for everything I could think of, but I didn't find anything with a solution to my problem. I am quite new to GIS tools and ...
0
votes
1answer
921 views

How to add the Delimited Text Plugin for QGIS 1.8?

I can't find the Delimited text Plugin- everything keeps telling me it's in the core build, but which core build? the Mac OS variant comes in multiple installers so without programatically unpacking ...
2
votes
1answer
301 views

View HTML field data with QT4 browers as a QGIS Run Feature Action Tool

I've successfully populated a sqlite table with an HTML-encoded-table as a field attribute, and so there is literally a Table within a single field value in sqlite, for each record. This is going to ...
2
votes
3answers
277 views

How to route railcars along railroads?

I'm very new to the world of GIS, but I'm learning a great deal from this site, as well as others. I fell like this should be 'easy' but I need to be pointed in the right direction. I'm trying to ...
0
votes
0answers
88 views

Display raster outlines

I guess mine is a very simple task, however I don't know how to solve it. I m trying to display the outlines of a raster created from a polygon shp. What I would like to come up with is an image where ...
2
votes
1answer
1k views

QPJ files on ESRI software

We have some GIS data, which was converted from AutoCAD dwg to TAB using mapinfo, then converted to shapefiles as that's what we are required to create. Editing the data fields was done in the shape ...
1
vote
0answers
119 views

Normalize with gdal_translate

I do not understand the command line when I try to work with gdal_translate in QGIS. I found this at the forum: Normalize raster values to 0-255 And tried this: *"If not, from within QGIS choose ...
5
votes
0answers
345 views

Modifying File GDB Feature Class Features Using QGIS

I've installed the File GDB API using the OSGEO4W advanced installation when installing QGIS. I've had a bit of trouble with it initially and have posted a few questions with some helpful Stack ...