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4
votes
2answers
11k views

How to clip a line layer based on polygons with QGIS?

I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons. I tried in QGIS the Vector -> Geoprocessing -> Clip ...
0
votes
0answers
1k views

How to convert lines to start points and end points?

I know there are several ways to convert lines to points in Qgis but I have not been able to find a solution that will convert the file so that it indicates if the point is the start point (upstream) ...
3
votes
2answers
3k views

Read gpx track points in QGIS

I want to read GPX track points with their time stamps into QGIS. I try GPS Tools, GPX Conversions, Waypoints from a track. This fails on my PC at office (QGIS code revision d94c044). Sometimes QGIS ...
0
votes
1answer
394 views

Set QGIS vector layer custom properties

I'm trying to set some labels and styles for some vector layers that are loaded programatically from a Spatialite database. I have the following code, which returns no error, and includes the changes ...
0
votes
1answer
291 views

How can I always run an algorithm with standard input shapefiles from mapcanvas in QGIS 2.0.1?

I created a model in the graphical modeler and I want to run that model always with two specific polygon shapefiles from my project, e.g. pst and astenot. Whenever I run my model, it asks me to set ...
0
votes
1answer
837 views

Field Calculator - replace string function - data value recognised as a column and is “not found” [closed]

I have the same challenge as GrahamD - Field Calculator - replace string function I have exactly the same challenge. Exactly the same as GrahamD's challenge, p abbreviated for pan. Type_2 as a test ...
1
vote
0answers
209 views

Why does the SAGA raster calculator fail when used in a Processing model?

I have a problem with the modeler and the saga raster calculator. When I'm using the raster caculator without the modeler it works fine. When I'm using the saga raster calculator in my model I always ...
2
votes
1answer
747 views

Qgis OSM and layer projection problem

I am using QGIS 2.1.0, and trying to import my vector layer(parcels) with OpenStreetMap layer. My vector layer (parcels) use EPSG 31277 coordinate system. This is the definition for EPSG 31277: (+...
2
votes
0answers
626 views

Google Maps Engine Connector error

I have recently installed the Google Maps Engine Plugin for QGIS 2.0 and it doesn't seem to work. Whenever I click on the Log in button it pops up with: Google Error:invalid_client Bad request. ...
1
vote
3answers
621 views

Table Relate Spatial and Tabular data in QGIS 2.0

I am self taught in GIS, so I apologize ahead of time for my noobness. In ArcGIS you have two options to associate data in a table to spatial data. Based upon my understanding, the first is Join ...
2
votes
1answer
141 views

How do I create smaller maps for publishing from multiple tiles representing a large map using QGIS?

I am completely new to cartography and QGIS - I'm a writer, editor and acceptable designer (Adobe Creative Suite). I wish to produce PDF tour guides featuring maps that display a route. One version ...
3
votes
2answers
4k views

How to use the replace string function in Field Calculator?

Within an attribute table I'm trying to replace one string with another using the 'replace' function . As an example, there are a number of features whose field 'NAME' contain the string '(B)' and I'...
2
votes
1answer
155 views

Loading / georeferencing OS rasters in QGIS

I have got some OS rasters but there isn't georeferencing file (TFW) with them. When I try to load them, it will obviously load in the wrong place. They are loading fine in a different GIS software (...
1
vote
1answer
201 views

What is the 'water retention capacity' tool and how is it used?

In the latest version of QGIS, I found a geoalgorithim in the processing toolbox that will generate 'water retention capacity.' I am familiar with DEM-based hydrologic modeling tools in QGIS, but I ...
1
vote
1answer
256 views

QGIS how to compute a trendline of two point lines? [closed]

Does anyone know how to compute a trendline for two lines of points? I have two lines of points of a 10 km long urban road. 1st line is one driving direction and the 2nd line of points ist the other ...
1
vote
3answers
962 views

How to access user credentials in database connection?

I am trying to automate a couple of things when a QGIS plugin is activated: If Layer A is not in the TOC, add it. This requests username and password to access a PostGIS table using the inbuilt ...
3
votes
3answers
1k views

How to draw (or add) a line indicating a specific latitude/longitude?

I'm trying to add a single line that show a specific latitude (e.g. the Tropic of Cancer) I don't want a gird but only a single line even in a vector layer.How can I do that I've try with pyQGIS ...
2
votes
0answers
472 views

Editing of vector layer programmatically with QGIS

I'm trying to edit vector layer using Python console and have couple of questions. Why this approach doesn't work and I have to use canvas.refresh? If I will use this code not in python console but in ...
0
votes
0answers
71 views

Problem with GRASS in QGIS

I am trying to import a vectorlayer to GRASS from QGIS. I get an error and hope someone here can help. Been trying to fix it for hours, but come no closer to a solution..... This is the error I get: ...
1
vote
1answer
231 views

How to fix QGIS crashes when using GRASS toolbox?

I've installed QGIS 2.0.1 on Ubuntu 12.04. exactly as explained on qgis.org . Unfortunately QGIS crashes when trying to use any GRASS model (r.aspect as example): just opening QGIS, click on toolbox ...
4
votes
2answers
2k views

keep the same field headers after joining a table to a shape file in QGIS

I noticed that after joining a table to a shape file the headers of each fields in the table used for the join are changed by QGIS and they are attributed to a different name. For instance, i had a ...
4
votes
2answers
157 views

How to replicate trunc function on QGIS?

I've search a bit before asking this question, but I haven't found the answer. Is there a Trunc function on QGis? I've tried using floor, but it doesn't work (like I want) if the number is negative, ...
1
vote
1answer
315 views

Is there a way to automatically calculate attribute values for new features?

I am creating a vector point layer which will be added to over time. I have been using the field calculator to populate fields such as X and Y coordinates. I'm wondering if there is a way to have ...
4
votes
1answer
2k views

How to pick the coefficient in Inverse Distance Weighted method?

I'm using QGIS 1.8.0 to interpolate weather data. This is, I have a weather station located in say, A and C. With the Inverted Distance Weighting or Triangular Interpolation methods, I can know/...
0
votes
0answers
914 views

Trying to make QT + QGIS working

I'm mostly a Java programmer, I worked on C++ many years ago, and knowing this my project manager has asked me to create a little app in Qt that can open a shape file, using QGIS. But I'm encountering ...
1
vote
1answer
906 views

QGIS, making a topo map from an excel file

I will appreciate your help. I am new to QGIS, this question might be common but trough me search I did not find the answer I needed hence my question here. How do I make a topo map ( raster) from ...
3
votes
2answers
2k views

QGIS 2.0.1. missing Google Mercator CRS

I've downloaded the latest QGIS version and I cannot add basemap. I installed OpenLayers plugin and while adding any map from list QGIS crashes. I tried to enable Google Mercator CRS first, yet it's ...
0
votes
1answer
25 views

QGIS 1.8 or 2.01 select entries in .shp file that match a field entry [duplicate]

I've got a .shp file with 40k points (trees) in it. One field is the species name. Is there a way to select those entries that match a desired field name e.g. 'black walnut' so I can move them to a ...
3
votes
1answer
249 views

How to get projected centroids in QGIS?

I am trying to get a centroid for several polygons on a global scale, in a way that it would correctly represent the common centre of all the polygons, taking Earth's curvature into account. The ...
0
votes
0answers
183 views

How to install GRASS in QGIS Dufour?

How do I install GRASS to run in QGIS 2.0.1? GRASS is not listed in the Plugin Manager and attempting to access it via the Processing Toolbox gives me the following error:
0
votes
0answers
104 views

How do I shorten the refresh rate of qgis_mapserv.fcgi?

Is there a way to shorten the refresh rate of qgis_mapserv.fcgi? After having uploaded a revision of a file these changes do not take effect in qgis-web-client. I guess it's because the computed tiles ...
2
votes
1answer
43 views

Get coodinates from point shapefile

I converted a line shapefile to points as you can see in the attached image. Is there a way to know the coordinates of each point? Any help would be really appreciated! PD Im using QGIS 1.8.0
2
votes
2answers
214 views

Merging contour lines along tile boundaries

I am working with the CANVEC data set. The data in canvec is broken up in to mapsheets. eg. 116B04. I have data covering the entire province of the Yukon. I have merged all the data in to one ...
0
votes
1answer
165 views

How does QGIS Topology Checker check the topology of SHP and OSM files? [closed]

Can anybody make me clear if .shp & .osm (OpenStreetMap Data) are holding topological data/relations or not. if .shp files are not holding then how qgis plugin topology checker checks for the ...
0
votes
1answer
212 views

Is it possible to connect to FEMA's WMS and WFS using QGIS?

I have just found out about the wonderful world of WMS and WFS. I have added the FEMA versions of both to QGIS. WMS and WFS. The WMS seems to connect and adds something to QGIS, yet it is not visible. ...
0
votes
0answers
610 views

How to share ArcMap shapefiles with QGIS?

I'm trying to send a ArcMap 10 shapefile for a QGIS user and something happens with attribute table during the process. Columns will be rearranged, hidden digits will appear to coordinate columns and ...
7
votes
1answer
483 views

Can I create a reusable text annotation style in QGIS?

I want to create a fairly simple map with a few locations emphasized using annotations. I don't like the default annotation formatting: So, I've reformatted the annotation background color, ...
11
votes
3answers
2k views

Ortho Projection produces artifacts

I`m trying to create a sphere-like view using qgis and the "world from space"-projection http://spatialreference.org/ref/sr-org/6980/ (essentialy an ortho-projection). ArcGIS wraps the shapes ...
1
vote
0answers
193 views

Using 3d Polyline in QGIS to calculate Volume?

This question may be completely off the mark. I have a survey drawing in DWG format, I use AutoCAD 2d but the survey was created in LSS. The Countour lines in the DXF have XYZ coordinates. Firstly ...
1
vote
1answer
465 views

How to automate creation of PNG maps using Python?

I have a project with 50 vector layers and I have done custom styling for them. Now I want to make around 30 png files with different xmin, ymin, xmax, ymax. The output size (png) should be width 139....
3
votes
1answer
231 views

What are the set of projections that can be accurately georeferenced using polynomial 2?

Background I'm starting with a map from the internet (Encyclopedia Britannica) and georeferencing it using QGIS 2.0.1, I get really accurate georeference solution using polynomial 2 transformation: ...
0
votes
1answer
82 views

QGIS 2.0 Plug In Repository - How to Set Parameters to qgis=1.8

A number of very useful QGIS plug ins available in 1.8 are not available in 2.0. Is there a way to set the parameter page in "Repository Details" to 1.8 so I can access the 1.8 plug ins and check ...
8
votes
3answers
2k views

Python error with open layers plugin QGIS 2

I've been using QGIS for a while but since using QGIS 2 the OpenLayers plugin doesn't work for me on my home pc. (However, I have installed the same version at my workplace with success.) I have ...
2
votes
1answer
135 views

Find GPS midpoint and SD of GPS coordinate along a certain heading in QGIS

I have a set of GPS coordinates (x, y) along with heading information. The heading for these coordinates is more or less the same and the coordinates are within a few meters of each other. How can I ...
2
votes
1answer
490 views

Which data providers support loading attribute tables without geometry?

I have a table in Memory from a cx_Oracle query (a list of rows, and a list of field names and their types) in my python plugin and I want to load it as a geometry-less layer (Attribute table) in qgis....
2
votes
1answer
1k views

How do I run the nvis tool in QGIS GRASS?

I am trying to follow this workflow: [How to generate a DEM from a countour Shapefile?] and it's running fine, and when I hit view output or view results I end up with a flat raster with shading ...
1
vote
0answers
45 views

problem on loading kriging outputs [duplicate]

My problem is the following: everytime i run ordinary kriging or other interpolation techniques i obtain this error message from QGIS Notice that these are the details for SAGA I would like a ...
3
votes
1answer
706 views

How to create DEM from contours without ArcGIS Spatial Analyst licence?

I'm trying to create a 3d DEM/DTM from a flat contour shapefile which has height data attached to each contour, but I'm not sure how to do this? I've found this post, on creating a dem from contours ...
2
votes
0answers
229 views

Can QGIS display projected coordinate system for map, at same time as lat/long graticule and scalebar in km? [closed]

I am aware of this question, which was posted a year ago, but its accepted answer appears to be a workaround rather than a solution to the issue which is the subject of this Question. I wish to ...
0
votes
1answer
82 views

Export data of points and polygons which are intersected

I have a shp file of roughly 100 Polygon. I also have a corresponding list (including X,Y data) of about 3000 points, in a csv file. Overlayed within QGis the 100 polygons contain about 90% of the ...