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

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0answers
12 views

where are old function of qgssymbol

in the new version of qgis 2.8, in the c++ API and in the class QgsSymbolV2, a lot of function has been deleted, by exemple setfillcolor, setcustomtexture, setnamedpoint, setpointsize i would like to ...
2
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0answers
23 views

Setting constant input layer in QGIS modeler?

I have a model in QGIS where there are two vector layers that remain the same everytime I execute a model. Is there a way that I can configure my model so that these layers don't require the user to ...
1
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1answer
80 views

QGIS forms: How to limit available values in a dropdown field according to value selected in a previous field

I'm building a rather complex entry form for the layer stored in a PostGIS database. I have a following usage scenario: On several occasions i have dropdown fields which let user select a type of ...
3
votes
1answer
76 views

Problem with distance in QGIS

I start a new project with base on OpenLayers plugin but if I check the distance on QGIS with distance tool (I choose a straight road) I view 5.466m on QGIS and 4.300m on google (by walking). How is ...
2
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0answers
41 views

How to change the symbology of selected features in QGIS

In QGIS selected features are normally highlighted in a different color to draw user’s attention on the selection. The default color can be changed programmatically. As a nice to have my standalone ...
1
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0answers
31 views

Object based classification using segmentaiton - QGis and Orfeo toolbox

I would like to apply an object oriented classification of Land Use and Land cover changes based on image segmentation of a Landsat 8. I am using Linux Mint 17.1 (64bit) and QGis2.8.1 and Orfeo ...
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0answers
42 views

calculate Z~F from polygon and raster

I have a polygon shapefile and raster layer. How I can calculate the elevation and area (Z~F) relationship for each polygon by using QGIS or ArcMap?
1
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0answers
12 views

Creating an Action using the Value column in Value Relation widget

I want to create an Action that would use the attributes (such as report_id and county) of a site_investigation_report feature to generate a file path to a PDF report. The county attribute uses the ...
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0answers
34 views

I am clipping my data points but the clipped layer is empty

I am new to QGIS and using QGIS 2.8.2. I have some points data of a whole town and I want to clip a specific region of data from it using a polygon layer. I am clipping my data points but the ...
4
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1answer
110 views

Raster to vector (polygons) with generalisation

I have created rasters showing different types of vegetation (bushes, trees, open land) with help from lidar data. Now I'm looking for a method to turn these images into polygons. I'm using a Mac ...
1
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0answers
22 views

New Issue with Open Layers Plugin Google Satellite - low res?

Recently I've noticed this issue with the open layers plugin google satellite layer where the imagery is dark and of a lower-resolution than it used to be. I frequently use this imagery with ...
10
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2answers
196 views

How to create dynamic leader lines?

I'm trying to create dynamic leader lines by using a PostGIS view in addition to the QGIS „Move Label“ tool. CREATE VIEW leader_line AS SELECT gid, ST_MakeLine(geom, ...
2
votes
1answer
48 views

Get nearest node following segment

I am trying to get the nearest node from a point(Id 1) . The coordinates (lat/long) are input by an user . I am using some functions like pgr_nearest_node() or get_nearest_node() from get_nearest_node ...
2
votes
1answer
34 views

QGIS: Labels shifting to different locations after I save from the attribute table

I just started working with QGIS, and I'm having a problem with my labels. I have figured out how to manually move labels for the points on my map (thanks to this forum!)--I have edited the attribute ...
1
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0answers
52 views

Removing pseudo-nodes using QGIS Sextante plugin?

I have a road network (vector) that i'm interested in carrying out some space syntax analysis on. Predictably my GIS data is in a pretty terrible state. For example, there are a bunch of roads on the ...
2
votes
1answer
42 views

QGIS: raster image georeference and overlay

I've created a grid and points in QGIS which I used to survey. Using a test image at the moment and I'm trying to fit this image as an overlay within a boundary. When I insert the image it has a white ...
2
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2answers
51 views

Can the QuickOSM QGIS plugin be used with Overpass QL (rather than xml)?

The QuickOSM plugin for QGIS can support users with the generation of new Overpass queries (for beginners on Overpass like me). It does this using the xml query language. I'd like to also be able to ...
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0answers
10 views

QGIS: “Attribute index out of bounds” error when hiding fields and using Actions

I have a long table with autoincrementing fields that the user doesn't need to see. I changed them to "hidden" through the field attribute editor. The problem is that I'm also using Actions (a ...
1
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1answer
38 views

Extracting regional data from vector file in QGIS

In QGIS, I have a random points data (coordinates) with assign values I have plotted it in QGIS with CSV file and now I want to extract the specific region data. How would I do this? Please guide me.
2
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1answer
32 views

QGIS: regular points tool numbering

I've made a regular grid and regular points for a grid, I want to set this inside of a boundary so I have deleted the points outside the boundary. However, when I do this the ID still shows up ...
1
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0answers
24 views

problem when building a code under qgis 2.8 c++ api

i have this code QgsUniqueValueRenderer *lRenderer = (QgsUniqueValueRenderer *)pLayer->renderer(); QMap<QString, QgsSymbol*> lSymbolMap = lRenderer->symbolMap(); QgsSymbol *lSymbol = ...
1
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0answers
33 views

Cannot select linesegment in QGIS

Drawing a baseline in an attempt to make a grid. Have managed to draw baseline but cannot select using cad tools "select one linesegment" tool. Worked previously and I'm not aware that I'm doing ...
2
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2answers
61 views

Rotation field is missing in rule-based renderer in QGIS 2.6

I am trying to do rotation of point symbols in QGIS. I am working with rule-based renderer. In other types of classification there is a button advanced (for example in categorized renderer), where I ...
1
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1answer
35 views

How to convert/export a large number of attribute's information shapefiles to txt/csv format using a python script

I'm using the 2.8.1 Wien QGIS version. I have a large number (more than 5000) of shapefiles that I want to convert to a csv or txt files to extract, to tables, the atributte information. The ...
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0answers
39 views

Extracting Building Footprints using ArcGIS [duplicate]

I would like to know if there is a way to extract building footprints from some sort of widely available imagery in ArcGIS such as Satellite imagery, DEM or Lidar Data. I would like to eventually turn ...
1
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3answers
53 views

What's the parameters of heatmap formula on QGIS?

I want to calculate the values by hand to know which parameters effect the result in the image, but i couldn't able to do that because i didn't understand it. I tried with 500 mt and 1000 mt radius ...
1
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0answers
29 views

Clip only works on some areas, and not on others, despite being from the same dataset

I have a shapefile of provinces (nxprovincias), and another shapefile of small, disconnected areas ("protected areas") that overlaps with the provinces. I want to easily calculate the total area of ...
3
votes
0answers
36 views

Printing a 1" scale from 2.8.2 Print Composer

I'm working on a small-scale site survey in qGIS, and for engineering purposes I need to print physical copies of the map that can be used with an engineering ruler. Basically, I need a way to print ...
2
votes
2answers
50 views

Inverted shading with polygons in QGIS 2.8

Is there a way to modify the style of a poygon .shp file so that everything except the polygon is rendered as shaded? EDIT: see these images if you have trouble understanding. I am going for the ...
1
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0answers
22 views

Problem running intersect vector processing with line shp file and polygon shape file

I have been trying to run intersect on two shp files, one is line, the other is polygon. Although processing appears to take place and a new shp file is created and added, nothing is visible. I have ...
1
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1answer
20 views

How to get the upstream average of a raster data layer that falls into a river network?

I have a raster layer of a network of rivers and a raster layer of data I want to extract. For each pixel of the rivers, I need to know the upstream average of the data layer that falls into the ...
3
votes
3answers
43 views

Why does Georef'd image show as a large black area

Using QGIS2.4.0 I just added 2 maps to an existing project. Both are scanned images of pre-1800 plans. One is a jpg file, I georef'd and added to QGIS no problem and plan displays in the project. I ...
0
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0answers
28 views

Snapping feature nodes doesn't work after feature creation (filter involved)

I've experienced a strange behaviour during editing mode: I have set a filter to 2 features (polygons), part of on of my PostGIS layers: "name"='A' OR "name"='B' After that I have created a new ...
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0answers
31 views

Batch processing ( offset of font marker) in QGIS

I have a group of layers with type linestring. Every line consists of simple line and marker line (font marker). I have a batch file(csv) with offsets of font markers. Do you know if there is any ...
1
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1answer
33 views

Spatial Query: The query from “LayerName” using “FID” in field not possible

In QGIS Wien, I am performing a spatial query with two layers (points and buffer areas) and receive the following error when creating a new layer with intersecting features: The query from "LayerName" ...
1
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1answer
61 views

QGIS for geophysical surveying?

I need to make 30x30 and 20x20 grid layouts with co-ordinate points in the corners. These points then need to be relayed to a GPS to be able to set the grids out in person and then survey them. The ...
1
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1answer
28 views

Visualising Multiple Routes from pgrouting in QGIS

I am able to Visualise the Single Route from Source A to Target B by the following code in QGIS SQL "id" in ( SELECT id2 as id FROM pgr_dijkstra( 'SELECT id, source, target, cost FROM ways', ...
1
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1answer
61 views

Layers with the same CRS in QGIS do not line up

I am busy with a project where I have to layer a .dxf and a .kml file but the layers are not lining up. The .dxf file's coordinates are completely wrong and the scale also does not appear to math up ...
1
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2answers
76 views

How to select features containing specific text string using an expression in QGIS

I need to style a survey parcel polygon shapefile, based on whether the polygon is a mineral claim or not. Unfortunately, the only information on whether a polygon is a mineral claim or not is ...
1
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1answer
53 views

Calculating area using dissolve and merge but getting shapefiles with empty attribute tables in QGIS?

I have a shapefile of a country with the 29 provinces. I also have shapefiles with the areas which are protected from construction (there are 4 categories for protection, within 4 shapefiles. Some of ...
2
votes
0answers
27 views

From track+waypoints to elevation profile with waypoints

I have a track and waypoints (1) imported in QGIS. I want to calculate the closest point from every waypoint to the track (2). Then, I want a table with data that allows me to draw an elevation ...
0
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0answers
44 views

QGIS 2.8 Error 1: Can't Load reauested DLL

Greetings, I am attempting to run the Topographic wetness index tool in QGIS with Windows 7. When I run the tool, I get this error: SAGA execution console output C:\PROGRA~1\QGISWI~1\bin>set ...
1
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0answers
30 views

Creating random points using QGIS?

Has anyone else had any issues using the random points tool in QGIS? When I try using it I'm selecting the option to use a value input field. The tool starts but then freezes once it gets to the 10% ...
0
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1answer
40 views

QGIS2WEB white screen on export/preview?

When I export my QGIS2WEB project it goes through, but when it loads up in my browser after the export is done all I see is a white background with the zoom/minus feature in the top left hand of the ...
2
votes
1answer
36 views

How can I save a QGIS project with hyperlinks?

I have already created an hyperlink project using actions, it works, when I click on one point of my shapefile it opens a photo, but when I re-open the project, the action is gone and I have to create ...
2
votes
1answer
64 views

QGIS Plugins & Tools that replicate Select ArcPy Tools

I developed a complex python application for road generation from GPS Devices that uses a few Arcpy Tools. I want to try and replicate this Applications functionality using a freeware like PyQGIS ...
0
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2answers
49 views

QGIS2WEB Error when exporting to Leaflet/OL3

I am having all kinds of problems with the QGIS plugins fr exporting my map to Leaflet or OL3. Whenever I try to preview my project I just get a white screen with nothing. Then when I try to Export to ...
1
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0answers
24 views

How to create displacement vectors in QGIS using GPS points with different dates?

Is there a way to calculate and visualize displacement vectors in QGIS ? I have DGPS points taken at the same place (ground control points), but their position moved over time as they are located on a ...
2
votes
2answers
68 views

PostGIS - How to calculate linestring length from WGS84 after transforming from OSGB 36

I am having problems getting lengths from multilinestrings after transforming data from EPSG:27700 - OSGB 1936 / British National Grid to EPSG:4326/ WGS 84. I'm doing this conversion to import a ...
1
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0answers
20 views

line from min to max of a digital elevation model

I have some geometries as multipolygons and a dem (digital elevation model). I need a line from the max value to the lowest value of the dem for every multipolygon. Is qgis a tool i could use or do i ...