Questions tagged [qgis]

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

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22 views

Clipping by mask results in blank output

After clipping by mask in QGIS 3.6 the output file has been blank (empty). Raster file and vector mask file have the same projected CRS: USER:100029 - * Generated CRS (+proj=igh +a=6370997 +b=...
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0answers
26 views

Error georefencing an aerial image with QGIS (for relatively small area)

I have an aerial image (.jpg format) of a relatively small site and have been trying to georeference it and generate a corresponding .tif file. I followed several online tutorials, but I keep getting ...
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1answer
27 views

QGIS3 data defined overide not active

In QGIS 3.4 MADEIRA, I get no active "data defined override"; I click on the sybol right toio "Size", that I want to modify with a function. The words "data defined override" are pale grey and italic, ...
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0answers
21 views

Reprojected raster return only zeros from QGIS raster calculator

I am experiencing an issue when trying to use my reprojected raster in QGIS raster calculator; First, my raster is reprojected from degrees to meters. After that, I want to process the layer by ...
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0answers
46 views

QGIS GRASS plugin not found?

I have seen this question come up before and have tried the related fixes as best as I could but nothing seems to work. I am running the most recent LTR of QGIS, 3.4.8 but my GRASS plugin cannot be ...
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1answer
29 views

Simplifying polygon

I am trying to simplify the overlaying polygon (green). Aim is to fill the area which is marked orange (underlaying polygon). Which tool can I use? I have tried v.generalize and v.clean but none seem ...
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0answers
15 views

QGIS SCP plugin classification error [on hold]

I'm using QGIS with the SCP plugin. I want to segment hedgerows in my satellite image. So, with the plugin, I selected different area for the Nearest Neighbor algorithm. I have a correct preview of ...
3
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1answer
65 views

Building single sided buffer around categorized polygon layer

I need to build a 100m buffer around a categorized polygon layer using QGIS 3.2. The layer has four classes and no holes. The difficulty here is, that the buffer needs to be split into the 4 ...
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2answers
31 views

Converting point to polygon in a given distance

I'm working in QGIS 2.18 but I can work with QGIS 3 or ArcMap 10.2. I have a multipoint layer providing from a lasDataset where I've isolated the buildings. I want to create a polygon layer where ...
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0answers
31 views

Grouping layers by attribute value and finding nearest neighbour using QGIS?

I am new to QGIS. I have two layers (layer_a and layer_b) consisting of two sets of points. If I want to find the nearest point in layer_b for each point in layer_a, I can just use the Distance ...
2
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1answer
44 views

Recover lost polygons from shapefile in QGIS

I've committed a newbie error it seems in GQIS with a polygon shapefile. I wanted to remove about 15 of the 210 polygons, and put those 15 in another file. I made a duplicate of the polygon ...
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0answers
21 views

Exporting data to map? [closed]

I am using QGIS software( QGIS3) and I am trying to load a data set I computed using excel and converted this data into CSV accordingly. But now I can not figure out why the data does not appear on my ...
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0answers
30 views

Joining .csv with duplicate values to .shp layer with points and getting all points visible using QGIS?

My problem with QGIS (version 3.4.8) I have a .shp map layer containing point data of buildings. I want to join .csv spreadsheet to this layer so I can look into it and visualize different variables ...
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0answers
35 views

Multi-User QGIS Editing? [closed]

I'm having a shapefile which I want more than two users to work simultaneously from different location on that file. What the easiest way to do this? PostGIS Database? QGIS clients? Or any ...
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0answers
14 views

How to use the Raster Calculator in PyQGIS (Console) in QGIS 3?

I want to use a script to do some raster calculations. I found this and this posts which seem to answer this question, however, it seems that they work for QGIS 2 and not for QGIS 3. I think the ...
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1answer
19 views

How to mask raster image (DEM) on QGIS Grass

I am doing research at graduate school. Using QGIS GRASS, I made a raster image (DEM) by spline interpolation from point data. Next, I decided to limit the range to within the vector (within the point ...
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0answers
73 views

What are the arguments for QgsDistanceArea().setSourceCrs() [duplicate]

I am really struggling with migrating a custom plugin from QGIS 2.x to 3.x. Below is a code snippet that seems very straightforward, but I can't find documentation that I understand for setSourceCrs()....
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0answers
19 views

Issue displaying UTM coordinates in QGIS 3.6.1

I am having trouble properly displaying my .shp layers in UTM (QGIS 3.6.1). Whatever I do, the coordinates always display as lat/ long, and measurements are way out. I have re-saved all my .shp layers ...
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1answer
36 views

Turning one column to multiple columns in Attribute Table?

This is kind of a two-part question to see which route would be more efficient. I'm trying to display a label in a shortened version, but the info is all in one column: Township 1 South Range 20 ...
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0answers
16 views

QGIS - How to add joined values table data to shapefile

For some reason I lost my previous question here but I proceeded a little bit after upgrading to the newer version of QGIS. My problem was combining spreadsheet .csv data to the .shp map layer, where ...
2
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1answer
52 views

Identifying unknown map projection for image

I intend to georeference and create a shapefile for some of the features but I'm unable to determine the correct map projection. (Working in QGIS ideally.) The image is from a scientific study but ...
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0answers
12 views

How to generate a layer of points from a database of lat, long using qGIS? [duplicate]

I am a programmer but I am new in QGIS. I have a database of some hundreds of points with lat, long information. It is an excel spreadsheet. How can I create a layer of points of each lat, long from ...
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1answer
36 views

Python code indentation in QGIS [closed]

I'm writing Python macros in QGIS project properties/macros window (3.4/3.6). I lose quite a lot of time correcting errors due most of the time to indentation errors. I find QGIS macro window rather ...
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0answers
17 views

QGIS adding additional (excess) map detail

I'm having a problem with QGIS (3.2.3-Bonn) which I hope the collective wisdom here can help with. I'm currently trying to make a base map with GPS data on top. So far so good. I found a decent ...
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0answers
24 views

Calculate net elevation gain from a vector?

I have a vector data (path/route) with points equally spaced with elevation data (in the attributes table). The elevation data was extracted from a raster. I would like to calculate net elevation gain ...
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2answers
25 views

Pixelated result using SVG as label background?

I have points that are labelled with a 2-digit numeric attribute, shown by default with a circle background (white fill, coloured outline of 1 map unit, buffer of 1 map unit beyond the label). I have ...
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0answers
13 views

How do i get my country's geographical shape from Natural earth data

I'm new in GIS and QGIS. How do I get a country's border/geographical shape from the world's shapefile?
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0answers
24 views

Fine-tuning tooltip position in QGIS?

When the tooltip is activated on a geographical layer it pops up with the cursor on the top-left corner of the label thus covering part of it ... Is there any way to fine-tune this behaviour (without ...
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0answers
13 views

Finding the local extrema contour line on a DEM

I need to trace the top of a small levee on the side of a riverbank, based on a DEM. This line is similar to a contour line, except that it goes through the local maximum instead of a constant level....
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0answers
29 views

Loading collada into 3D view of QGIS using Qgis2ThreeJs Plugin?

I have been looking at documentation and other posts but cannot find a way to load a 3D model into QGIS. I Installed the qgis2ThreeJs Plugin. I have tried to load a collada file in a temporary ...
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2answers
68 views

Using Open Google Earth cache file in QGIS?

I have a Google Earth cache file. Is there any way to open the Google image from a cache file in QGIS 3?
2
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0answers
17 views

Moving individual labels & rule-based labelling in QGIS

I have been playing around with labels and came to a problem. Hopefully someone can pinpoint whether I'm doing something wrong or there is a systemic hurdle in Qgis. Are you allowed to move labels ...
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0answers
21 views

Learning Geocoding and addressing in QGIS? [closed]

I am civil engineer and I do not know much about QGIS but I need to get started. I have a project that creates an addressing system. Basically, I want to recover the area from OpenStreetMap, mark the ...
2
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2answers
63 views

Difference between WMS layers and XYZ-Tiles

When I want to download a basemap that represents my study area, I can use WMS Services or I load a XYZ Tile from lets say OSM. But where is the difference? Perhaps it's that XYZ-Tiles are always ...
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0answers
24 views

Getting duplicate values when joining .csv spreadsheet to .shp map layer using QGIS?

I need to join .csv/spreadsheet data to the .shp map layer. The join itself isn't a problem with same join & target values (building) but some data goes missing because of duplicate values. For ...
4
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0answers
30 views

QGIS shared project (monitor changes)

I have a software-development background with a powerful use of svn and git. I work now for a public authority with two offices far from one another. Two other colleagues and I are sharing several ...
2
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1answer
25 views

QGIS - Create buffer circle around particular point using its geometry

Can I create a buffer circle around a particular point using its geometry in pyQGIS? I have my code as below: myVariable = '123456' expr = QgsExpression( "\"identificatie\"={}".format(str(myVariable))...
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0answers
10 views

SAGA Topographic correction process will not change original

I am having a problem with processing a file with the "SAGA Topographic Correction" function. I have watch countless videos to see how other users set their parameters and I have had no luck. I ...
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0answers
17 views

Installing GRASS addons in QGIS 3- r.local.relief [closed]

I have been searching for possible ways to install an GRASS addon to QGIS. This issue was mentioned in some earlier posts, for instance: How can I add r.local.relief to the QGIS Processing Toolbox? ...
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0answers
64 views

QGIS: beautiful HTML/Javascript terrain profiles won't show in Atlas print

I managed to automate the creation of terrain profiles, using the beautiful "Highcharts" Javascript framework. The data source of the profiles is stored in an attribute called "elev_data" of my ...
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1answer
56 views

Relocating layer's source file in QGIS [duplicate]

Is it possible to change the directory of a layer's source file without deleting and re-importing the layer?
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votes
1answer
36 views

Any algorithm to draw lines inside a shape? [closed]

Let's say you have a circle and have all the coordinates (x,y) that make up the circle.... How would you create lines (vertical and horizontal inside it? What about a rectangle? What if you have the ...
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0answers
33 views

Processing Toolbox has gone missing from QGIS 3.4 Win OS. Any alternate method to activate Processing Toolbox other than through the Plugins Manager? [closed]

QGIS Crashes when I try to activate the "Processing" by clicking the Check Box in the Plugins Manager as advised in earlier answers.
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0answers
24 views

QGIS i.topo.corr not outputting file

I am very new to working with QGIS, but am familiar with ArcMap. I am performing i.topo.corr with the GRASS extension using Landsat 8 bands 2-7. For my parameters: Band 2 SRTM Raster elevation model ...
0
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0answers
17 views

QgsMeshLayer in memory

I am trying to create a Meshlayer in memory and tried this simple test in QGIS 3.6: from qgis.core import QgsProject,QgsMeshLayer proj = QgsProject.instance() uri="1.0, 2.0 \n2.0, 2.0 \n3.0, 2.0 \n2....
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0answers
30 views

Deleting text from Map Items in QGIS print composer?

I have been using QGIS for some time, and what I am experiencing is not something that I have had issues with before. It appears to be a gitch. I created a map in QGIS 3.6.2. Then, I exported it as ...
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1answer
37 views

Accumulate selections by expression using a for loop (Pyqgis)

I need to run a for loop to select features by their attributes, because the values are within lists (strkey and strvalue). I'm using the following script: k=0 v=0 layer = iface.activeLayer() for ...
1
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1answer
55 views

QGIS. Polygon doesn't repeat itself

In QGIS, I represent a polygon of the El Niño regions on the Pacific Ocean, as seen below: Now, what I need is that the regions of Oceania and East Asia are shown on the left side of the map, similar ...
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1answer
26 views

QGIS: Smoothing two polygon sets where polygons are nearly adjacent

I have two polygon sets, one representing cities, the other representing school districts. I am trying to create a relationship between cities and districts, but I have a problem where the cities and ...
0
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3answers
111 views

Export longitude and latitude

I need the exact values of longitude and latitude to do further calculations with those. Best case would be to have a list with all those dates and do the calculation with this. I exported from ...