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

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2
votes
2answers
394 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
336 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
652 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
498 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
173 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
772 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
119 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
105 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
291 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
257 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
172 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
224 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
1answer
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
684 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
314 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
115 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
330 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
132 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
261 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
142 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
803 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
136 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
250 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
275 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
490 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
998 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
195 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
126 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
891 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
117 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
81 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
119 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
832 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
263 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
240 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
76 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
105 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
286 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 ...
0
votes
1answer
78 views

Two different ways of labeling in QGIS Layouter

I've made a map with points and labels related to those points. In one area, the points are very dense, therefore, I'd prefer to create one small scale map and in the corner a large scale map, to get ...
1
vote
0answers
137 views

graduated pattern polygon fill

I'm sure this question is really really basic but I appeal to you because I hate the idea that I have spent 20 minutes trying to do such a simple thing... All I want to do is style a polygon layer by ...
2
votes
2answers
144 views

Looking for Floodplain Modelling instructions

I'm really new to GIS, yet I have a project that I am doing that is GIS entensive. I want to do a flood plain (for a river whose shapefile i have) and publish whatever output (its a map i presume) ...
1
vote
1answer
720 views

How to change vector attributes values?

I want to change vector attributes values. i could not get the command fet.setAttribute indeed, it is mentionned in http://hub.qgis.org/issues/7223 that: "The QgsFeature instance now must be ...
0
votes
3answers
696 views

How to rasterize a vector map?

I am looking for a way to create a raster grid from a vector map. I have a map consisting of shapefiles which I want to export as a raster with UTM coordinates. I was thinking of something using the ...
3
votes
3answers
108 views

Automated way to join

I have river networks (polyline) of several adjacent countries as shapefiles that almost match up at the borders, but not quite. Is there any way to automatically connect them to a consecutive river ...
3
votes
1answer
1k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
3
votes
2answers
823 views

PyQgis overwrite shape file and adding layer to Qgis

I am creating a shapefile in python by: driver = ogr.GetDriverByName('ESRI Shapefile') datasource = driver.CreateDataSource('c:/temp/toke2.shp') layer = ...
6
votes
1answer
125 views

Previewing File Geodatabase in QGIS Browser - Is it Possible?

Can I Preview/look at file geodatabase attributes in the QGIS browser if I have installed QGIS using OSGEO4W installer and FileGDB API? Currently I can add/edit file geodatabase feature classes to ...