Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
40,987
questions
4
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0
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SAGA Tool in QGIS Error: Load table: Proj.4-WKT Dictionary... failed
I have some problems with running SAGA tools in QGIS. I've downloaded and installed the software via the OSGeo4W Installer. It downloaded QGIS 2.12 and Saga 2.1.2. I wanted to use the Tool "Shapes To ...
2
votes
1
answer
92
views
applying a gradient to terrain curves in QGIS: problem
I'm trying to apply a gradient to terrain curves generated from a geotiff. I then choose a graduated style with a gradient color palette.
everything seemed fine until I noticed that from a certain ...
2
votes
0
answers
146
views
Split Polyline QGIS - Too Many Resultant Features
I'm trying to split a single polyline into 2 polylines (I have lines that loop back on themselves, and I need to split each one into two lines: one for going, and one for coming back).
When I use ...
0
votes
1
answer
127
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Reprojecting Tifs [duplicate]
When I import some geotifs into QGIS, they use a reference of 0, 360. My basemaps are all -180, 180. Both the basemaps and geotifs use the same CRS, WGS84. So the geotifs display starting at 0 on the ...
1
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0
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2k
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python script in QGis - help using gdal.Polygonize
I want to create a very simple script in python that polygonizes a raster.
Based on python cookbook + forums search I wrote the following code
#import des modules
from osgeo import gdal, ogr
from ...
3
votes
2
answers
879
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QGIS: Saving a Vector Layer renames the column field title as "cen2010_1", etc
I'm trying to create a custom subset block map of the 2010 Census shapefile for Massachusetts. I've joined population data from other DBF files and am trying to save the shapefile vector layer as a ...
1
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1
answer
478
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QGIS and 'Layer to labelled layer' plug-in
I'm giving a try to this plug-in and I noticed this:
When you use this plug-in on a layer, it adds a lot of field in the layer table.
The field LblColor has a 7 character field, but it needs a 'r,g,b' ...
1
vote
1
answer
757
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Spatial join multiple attributes from smaller polygons to the bigger one
I'm trying to join (to the rectangle) values from multiple polygons intersecting for this rectangle.
I've tried to use some Reference functions in Field Calculator like geomintersects() but it joins ...
1
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2
answers
217
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How to set independent path in QgsOverlayAnalyzer >> intersection statement using Python?
How to set independent path in QgsOverlayAnalyzer >> intersection statement using Python?
QgsOverlayAnalyzer.intersection(QgsVectorLayer, QgsVectorLayer, QString, bool onlySelectedFeatures=False, ...
1
vote
2
answers
843
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Mapinfo Vertical Mapper interpolation VS QGIS
I am currently trying to fade out the use of MapInfo and only use QGIS (or Global Mapper) however I find that I am still needing to use Vertical Mapper for interpolations. We are using MapInfo V12 and ...
2
votes
0
answers
2k
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Raster layer not visible after changing color rendering in Qgis
I created a new raster and it appears in the layer list, its visible on the screen and the values seems to be correct.
When I change the "band rendering" from "Singleband gray" to Singleband ...
1
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0
answers
32
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QGIS 2.12 symbology does not work correctly [duplicate]
I use QGIS for a long times on mac and windows and I have a problem with the 2.12 version on my OSX 10.8.5 when I want to edit style of my vector layer.
When I click on properties of a vector layer ...
6
votes
1
answer
315
views
Centrally stored QGIS print templates
In my organisation we would like to have a set of organisation configured print templates. It would be convinient to stores these at some central location so we only have one copy of the templates.
...
5
votes
1
answer
486
views
Get values from metatada.txt
Is there a built in function in PyQGIS to import the values from a plugin's metadata.txt?
I am developing a plugin and want to show the version corresponding to the value from metadata.txt. Is there ...
4
votes
1
answer
3k
views
QGIS : Creating point feature from Lat, Lon SQL Server 2008R2 data import
I am importing a table having no spatial columns from SQL Server 2008R2 database into QGIS 2.10.1. The table has latitude & longitude values. How can I create point features using the latitude, ...
3
votes
1
answer
276
views
How detailed should I make the shapes.txt for a General Transit Feed?
I am working on creating a transit feed with General Transit Feed Specifications in mind. I'm torn into how detailed the routes should be for the shapes.txt. Do I map just when the bus is on the main ...
3
votes
1
answer
5k
views
Using processing.runalg in python script
I'm trying to run the following python script:
from qgis.core import *
import sys
import os
import qgis.utils
from qgis.analysis import *
app = QgsApplication([],True,"")
# supply path to where is ...
1
vote
0
answers
58
views
Print composer: Frozen layers disappeared after server migration
I am currently working on a project file with around 30 print composers using different layers. Some of the layers come from a PostGIS database connection, others were imported through the Add Layer ...
6
votes
1
answer
4k
views
OpenStreetMap and Country Borders in QGIS?
I am new to QGIS and I am using OpenStreetMap and OSM place search to create a map for latin america. However the peruvian terrritory includes the maritime area. How can I avoid/modify this. All other ...
12
votes
2
answers
3k
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What is the difference between spatialreference.org catalogs: EPSG, ESRI, and User-defined?
I'm trying to understand EPSG codes. I've been to the spatialreference.org site, and in its "about" link, it states:
"There are currently three distinct catalogs of spatial reference systems on this ...
1
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1
answer
315
views
Saving edited vectors to new file does not save changes?
Perhaps I do not understand how QGIS saves edits but here is what I am experiencing.
Load up a vector .shp file
Immediately "SAVE AS" and give it a different name.
Delete some vector lines on the new ...
7
votes
3
answers
2k
views
Is there a way to have a 'live' buffer in QGIS
I use QGIS (2.10.1) to create buffers around polygons. I often create a series of buffers, and later need to edit the underlying polygons. It is frustrating to start from scratch in re-create ...
1
vote
0
answers
129
views
QGIS Time manager [closed]
I am trying to use the Time Manager plugin in QGIS to create a time series of some raster data. I get the following error message:
AttributeError: 'QgsRasterLayer' object has no attribute '...
5
votes
1
answer
284
views
Print Composer using input from several Spatialite-tables with PyQgis
How can I create PDFs out of QGIS using the Print Composer Templates that include a lot of text (from a text-template) and within the text several information comes out of my spatiallite-database. A ...
3
votes
2
answers
2k
views
how can I speed up openlayers plugin for Google images in QGIS?
I use Google aerial photos when using QGIS (2.10.1) using the openlayers plugin.
I find that it is very slow, and often hangs when I refresh or move around the map.
Is there a way of improving its ...
3
votes
1
answer
391
views
Duplicate print composer or use template?
I want to duplicate a print composer in a project to use with a different atlas coverage layer but I am having problems generating the atlas.
I have tried to both duplicate the print composer in the ...
7
votes
1
answer
582
views
How to index large VRT files in QGIS?
I have a large number of small tiles merged into a single VRT. The rasters are only viewed at large scale, so only a few of them are visible at the same time. The map refresh in qgis is slowing down ...
3
votes
0
answers
666
views
How to find mountain-peaks in SRTM TIFF
I'd like to identify mountain-peaks from an SRTM TIFF (created/composed from the original HGT ones).
How I'd wish it would work: Check for each pixel whether it is the highest value within a given ...
3
votes
2
answers
790
views
How to open and save QGIS datasource with/to lower case fields?
I want to be able to change all field names to lower case from a data source when loading them in QGIS (SHP in particular).
Is it possible? Via the GUI, via Python.
Is it possible to convert field ...
5
votes
1
answer
717
views
Initialising QgsFeature with predefined field names using PyQGIS?
I need to create function that assembles QgsFeature from scratch: takes id, dictionary of attributes, and geometry as input. The issue is that feature that is being created doesn't belong to any layer ...
1
vote
0
answers
3k
views
WMS layer throws "IReadBlock failed at X offset 0, Y offset 1" error. Possible XML issues
I am working with a few WMS layers to try and see which one would work best with an application I'm developing out of QGIS 2.8. I need the CRS to be in EPSG 4326 but, as many of you know, most webmaps ...
3
votes
1
answer
2k
views
Coordinate translation in QGis?
Is there a way to apply an arbitrary coordinate translation to a layer in QGis 2.8.2? I have some data sets that are in a truncated coordinate system, and I need to shift them by a certain amount to ...
2
votes
1
answer
821
views
Generating circular histogram plot of joint directions from vector layer in QGIS?
I would like to extract the joint direction from a vector layer. Joints are best described 'relaxation fractures' found on rock outcrops are are easily visible if no vegetation exists. The orientation ...
1
vote
0
answers
159
views
Render single band gray raster define gradient and cumulative cut
I want to save an image with these characteristics:
gradient: white to black
std deviation = 5
Until now I get to apply the gradient but the minimum and maximum values are used instead of cumulative ...
1
vote
1
answer
917
views
Why should Google Earth's satellite imagery differ from what is available via the Openlayers plugin on QGIS?
I suspect that there's likely to be a relatively straightforward explanation of why, in some instances, satellite imagery on Google Earth may differ from that which is available from Google Maps on ...
1
vote
1
answer
250
views
How to create a map from separate ascii files without merging them?
I have three ascii files including longitudes, latitudes and pixel values. I just wonder whether there is anyway to display a map from the three files and save it in geotiff without merging them into ...
9
votes
1
answer
270
views
Styling polyline to view which part is above another in self-intersection in QGIS?
I need to view a polyline constructed from waypoints of a gps track that has self intersections in curves; like an exit loop from a highway.
I need to visualize it in a way that shows which part is ...
1
vote
0
answers
46
views
Should I set the projection if the data has already been projected?
I need to plot some data which was produced on a native grid with a lambert conformal conic projection. I need to create a geotiff (using python and gdal) and was wondering how to go about and do ...
1
vote
0
answers
85
views
Spatial Join with start and endpoints of polylines in QGIS?
I want to join 2 layers. One of them is are polylines and has two pairs of lat/long, representing the start and the end.
id lat_start long_start lat_end lat_start
The other layer is a ...
2
votes
1
answer
170
views
Problems with labels in QGIS 2.10
I want to label my polygons with information, and I want the labels to be in two rows - name on row 1 och volume on row 2.
My problem is, that I get an extra "quare" at the end of row 1?
That has ...
1
vote
0
answers
154
views
Querying for points within polygon in MySQL?
I have polygon in this format
POLYGON(23.816364700000001 87.574939799999996 ,23.814872699999999 87.572279100000003 ,23.812595399999999 87.572279100000003 ,23.809925700000001 87.571678300000002 ,23....
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0
answers
145
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Making contour lines out of points with different heights using QGIS?
I have different points in a polygon. The points have the attribute "depth" and either have 0m, 2m or 4m depth. My task is now to create some sort of contour lines with the points with the same depth ...
2
votes
1
answer
122
views
Displaying label text when polygon layer is rotated in QGIS?
How can i have the text labels display when the layers are rotated? I have several polygons layers rotated and i can not get the label text to display. When the rotation is removed the label texts ...
4
votes
1
answer
3k
views
Calculating shortest paths from all points in one layer to any points in another via road layer in QGIS?
I'm trying to calculate the shortest paths from all the points in a layer representing population settlements (the green points) to any of the points in another layer representing the hospitals (...
1
vote
1
answer
2k
views
QGIS - how to see the minimum and maximum elevations in contour layer
I am using QGIS 2.12 on a Macbook Pro running OS X Yosemite 10.10.5.
I have a contour layer representing elevations. How can I find what the maximum and minimum elevation values in the layer?
2
votes
1
answer
291
views
Visualizing large number of WKT files in QGIS
I have a directory which stores the result of breaking up a big geometry into many parts. There are 100 files named part-0000.wkt to part-0099.wkt. I need to point QGIS to this directory and have it ...
3
votes
0
answers
322
views
Why doesn't the Undo/Redo History Widget run my custom undo/redo methods?
We're writing a Python plugin for QGIS 2.8.3. I've derived a class from QUndoCommand to contain "undo-able" work. When I push it onto the undo stack, its redo method gets called as expected, but QGIS ...
2
votes
1
answer
153
views
QGIS simplify geometries shifts polygons north
I'm trying to simplify polygons in a shapefile using the "Simplify Geometries" tool in QGIS 2.10 (Pisa). This works as expected, except for one strange effect: the resulting features (shown in green) ...
1
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0
answers
323
views
QGIS Data Frame scale
I am trying to setup the Data Frame in QGIS to a minimum scale of 1:0 like ArcMap does. Zooming in goes down to 25.000:1
Any suggestions?
1
vote
0
answers
563
views
QGIS and Android Tablet
I can't download QGIS 2.8.2 via googlePlay. Device is not compatible. Device is Nexus 7 2012 with android 5.1.1
Do you have same issue? On old android 4.4 it was working fine.