Questions tagged [qgis]

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

Filter by
Sorted by
Tagged with
0
votes
0answers
8 views

Point Sampling Tool Output Empty

I am trying to extract elevation values for each point in a point .shp from a DEM. Both files align and are in the same CRS - 4326. The tool runs but I receive an error message and the output file is ...
0
votes
1answer
9 views

Saving Output of Algorithm using PyQGIS

I'm new to PyQGIS and trying to save the output of the processing tool 'create points layer from table'. I just need to save it as a shapefile. My code is below which seems to be functioning so far. ...
0
votes
0answers
14 views

Error in merge function “Erreur de géotraitement GEOS: la différence a échoué”

I am trying to merge three large shapefiles. After cleaning all the inconsistencies and artefacts, the merging of file 1 and 2 ends well, yet with the following message (sorry to be in French): L'...
1
vote
1answer
32 views

CRS setting in QGIS?

I'm working with this CRS: "EPSG:32632 - WGS 84 / UTM zone 32N - Projected" in a Qgis3.4 (long term release) version. When I try to add a raster file with this CRS:"EPSG:25833, ETRS 1989 UTM Zone 33N" ...
0
votes
1answer
18 views

Digital Terrain Analysis - Roughness Index

Currently I am working on a project dealing with terrain analysis based on a DEM. I came across the term "roughness index" using slope values from that specific DEM. On YouTube I found a video, which ...
2
votes
2answers
59 views

Automatically fill gaps and merge freshly generated polygons with the longest adjacent polygon

I get polylines automatically generated from AutoCAD from a colleague. Converting them into polygons with QGIS 3.6, I find out some sliver polygons and gaps in between, as shown in the picture below : ...
3
votes
2answers
1k views

Where are QGIS application setting file(s) stored?

I have some application settings (Windows/QGIS v2.0) that I would like to pass to other users (such as those settings defined under Settings menu>Options>Rendering tab). In ArcGIS they are stored in ...
0
votes
1answer
32 views

Polygons out of a shapefile in QGIS

I have added a layer with tracks and track points from OSM in QQGIS and exported this GPX file into an shapefile. Now I wanted to calculated the area of the buildings. I tried to do this with the ...
0
votes
0answers
15 views

QGIS polygon to line with neighbor info

Is it possible to create lines from polygons with information about neighbors in QGIS? I would like to do this for land plots. There is a tool in ArcMap that works like a charm, but I do not see ...
2
votes
1answer
34 views

Coordinates of an area on a raster in QGIS

I am new to GIS and I have to do the following: I have a GeoTIFF raster file of a map with some features like clouds and water bodies. It is a satellite image. My images are taken from a snapshot of ...
1
vote
1answer
30 views

IDW in QGIS 3.8

I'm trying to create raster interpolated layer by using the IDW tool. this is how my original points layer looks like: this is what I did in order to get the IDW interpolation: and this is the ...
2
votes
0answers
39 views

Installing QGIS using software distribution?

In our company we use QGIS 3.4.8 (LTR). To install the same version for each user in a short time we use the rollout software, Baramundi. It works for the most installations, but for one installation ...
4
votes
3answers
8k views

Showing only selected features from attribute table on layer using QGIS?

One of the layers has around 5000 attribute entries, based on a CSV file of species records. All the features are of course shown on the map layer. How can I select a specific class of features so ...
0
votes
0answers
38 views

Exporting XY-data to a new shapefile [on hold]

I got an csv.file with 29 rows and 2146 columns including coordinates and a number of reflectance for each wavelength starting from 350 up to 2500. I imported the csv.file in qgis without any problems....
0
votes
0answers
293 views

Adding Esri Vector Basemaps to QGIS?

I am wanting to add the ESRI Vector Basemaps http://www.arcgis.com/home/group.html?id=30de8da907d240a0bccd5ad3ff25ef4a#overview to QGIS 3.4. Does anybody have any suggestions on how to do this?
1
vote
1answer
76 views

How to correctly use the filter with empty values in pyQGIS?

In my script, at the moment of having the layers loaded, I filter all the ToC layers with a unique value for all the layers. I use the setSubsetString('"FIELD" = \' VALUE \ '') method, but when it ...
1
vote
0answers
42 views

Getting value from another table with dbquery

I am trying to use dbquery to get a value from a table when a record in it is the same as a value in the source table. In the table where I need the value-added (Sewerage_Manholes...) I am trying ...
1
vote
2answers
92 views

QGIS Field Calculator Aggregation with a intersect query

I have point (manholes) and line (sewer main) datasets and want attributes from the points at both ends of the line. If I run the following after I install RefFunctions in field calc on the line ...
0
votes
0answers
18 views

Get value from point layer based on start/end of line layer [duplicate]

I need to get a value from a point table based on the end/start point of a line. This is similar to my question QGIS Field Calculator Aggregation with a intersect query aggregate( layer:= 'Point_Clip'...
0
votes
1answer
38 views

Importing LiDAR tiles? [on hold]

I've been provided with a number of LiDAR tiles which appear to be irregular point clouds in x,y,z .grd format. I've been trying to merge them and produce a DEM for use in modelling. When I can ombine ...
7
votes
1answer
2k views

Comparing GRASS v.Overlay/QGIS Intersect Speed intersecting line and polygon? [closed]

Im currently trying to convert my scripts from ArcGIS to QGIS but one aspect that is extremely slow is trying to intersect a polygon with a line feature. I feel as though there must be a better way to ...
8
votes
1answer
2k views

Automatically reducing polygon size in QGIS?

I am working with two polygon layers (counties & states) which I will 'intersect' to find which counties are within which states. Due to data inaccuracies I have to change all county polygons and ...
0
votes
0answers
44 views

GPKG and GPKG-WAL - not sure if main process finished

I am performing ZonalStatistics (mean value from a Float32 virtual raster) in QGIS 3.4 on a huge geopackage layer. Originally it was 240 GB and after few days the process became odd: The QGIS process ...
1
vote
2answers
3k views

Clipping lines vector layer to polygon layer in QGIS?

I have a lines layer (a contour map of mean annual precipitation in Africa) that I want to clip to a polygon layer (shape of the African continent). However every time I use the clip tool (Vector-->...
-1
votes
0answers
21 views

Seeking reference on Landsat-7 SLC off gap filling by inverse distance weighting interpolation method?

Can anybody provide a reference article or publication which has applied inverse distance weighting interpolation method in QGIS to gap fill the Landsat-7 SLC off imagery? I have done the gap ...
1
vote
1answer
36 views

Simplify Slider

QGIS 3.4 appeared to have a slider for adjusting the simplification tolerance - at least that is what shows up in the 3.4 documentation, for example: https://docs.qgis.org/3.4/en/docs/training_manual/...
1
vote
1answer
54 views

Correlate two different zone system records

I am working with two data sets from different sources that represent the same phenomena and have a challenging point. Both data sets represent demographic attributed of the population [ person id, ...
1
vote
1answer
29 views

Accelerate neighbor analysis in QGIS PostgreSQL / PostGIS

For a project I have to show the relationship between 2 or more objects. For this I use the code below in QGIS in step 1 I determine the relation in step 2 the items are counted. In the test set I use ...
-2
votes
0answers
44 views

Calculating the area of buildings in a Esri shapefile in QGIS

I need the area of certain buildings of a shapefile. So far I did not find a solution to get these values in the attribute table.
4
votes
2answers
89 views

Export CSV from QGIS without thousands separator

I need to export a GeoPackage file from QGIS 3.2 as CSV file. The GeoPackage contains two fields: UID as Integer and S_SCH as String (yes, it really is a string). It looks like: UID S_SCH 654321 ...
2
votes
2answers
68 views

Extract the attribute names from a large number of Shapefiles

I happened to need the attribute names of a large number of .shp files. Is it possible under Linux, without importing the files into a GIS?
0
votes
0answers
23 views

Unable to import GDB folder in QGIS 3.8 [duplicate]

I'm trying to import a GDB folder, downloaded from https://data.geo.admin.ch/ch.swisstopo.geologie-felsoberflaeche_hoehenmodell/ into QGIS 3.8 but I get an errormessage that data source is invalid. I ...
3
votes
2answers
950 views

Error gap-filling Landsat 7 SLC-off with QGIS 2.18.3 on Windows 10

I am trying to gap-fill Landsat 7 SLC-off images with open-source software as explained in the comment below this post. I'm new to QGIS and have almost no knowledge with Python (I'm a GIS novice ...
2
votes
0answers
26 views

Is there any way to reorder layers in GeoPackage and change the default naming in QGIS?

I have successfully saved several layers in one GeoPackage in QGIS 3.8. This is how it looks like in DB manager: I found out that the ordering of the layers is somehow strange when loading the GPKG ...
3
votes
1answer
43 views

Calculate the travel time from locations to the closest N points

I want to calculate the travel time (based on walking time) from locations to the closest N points of another dataset. Then I want to create a hull around those N closest points per location Is this ...
1
vote
1answer
26 views

Tweak raster calculation

I’m creating layers with qgis 3.4 raster calculator. How can I go back and modify the calcs or do I have to start over every time?
0
votes
1answer
33 views

QGIS Does Not Contain Filter

In QGIS 3.4, how do you perform a does not contain filter? I know how to perform a contains filter, with the LIKE / ILIKE operators, but how do you perform a does not contain filter?
0
votes
2answers
51 views

Geographic coordinates in PostGIS to QGIS and shapefile layers

I've got in PostgreSQL/PostGIS the table "points" with latitude and longitude fields. I've done update points set geom = st_point (longitude, latitude); and also select updategeometrysrid ('points'...
2
votes
1answer
44 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 ...
0
votes
0answers
16 views

Extracting current and future individual RCPs (2.6, 4.5, 6.0 and 8.5) for Current, 2050 and 2070 and specific months [on hold]

Worldclim has several GCMs (global climate models). Has Four RCPs (representative concentration pathways) (2.5, 4.5, 6.0 and 8.5). Has three time steps (Current, 2050 and 2070). How can I use R or ...
2
votes
2answers
54 views

Clipping Lines Using Expression in QGIS?

I have a set of roads that I wish to clip. How ever I only need a segment of each road based on the state its located in. I can do this independently but seems like there should be a better way. Ill ...
11
votes
3answers
5k views

Need to Quickly Add Multiple Layers From Multiple Folders To QGIS Project

I have downloaded several imagery Zip files (content of each is jp2, jpg, jpw, xml, htm, and .dbf, .prj, .sbn, .sbx, .shp, .shx) and would like to quickly add this imagery to my working project in ...
0
votes
1answer
46 views

Editing PostGIS multipoint table with QGIS

I created an empty multipoint table in PostGIS and I want to fill it with hand-placed points in QGIS. I have connected them and checked that QGIS identifies the new layer as multipoint. I've got a ...
0
votes
2answers
38 views

Downloading files with file paths informed by attribute information

I am looking to download files that are saved in a server location with a file path that is informed by attribute information created in the graphical modeler. The information that I would like to ...
2
votes
1answer
32 views

QGIS dll load fail with from qgis._core import *

I have a error in console python, I tried using pyqgis without qgis interface. My problem is when I use: from qgis.core import * Console's the message is: from qgis.core import * Traceback (most ...
1
vote
1answer
43 views

Merging a legend and a table

I'm using QGIS 3.4 for this, and am creating a map that will see quite a lot of use. It will show plant species, and the area of the plants in question. For this, we have a main "plant" table. This ...
1
vote
1answer
32 views

Where did Merge go in Raster menu?

I am using QGIS 3.6.2-Noosa. Last time I merged rasters (a couple of weeks ago) I had options on the Raster Menu that are mysteriously gone now (I would merge via Raster>Miscellaneous>Merge). Now when ...
1
vote
0answers
37 views

Large offset between two identical vector layers

I want to have a dxf layer to overlay another layer. The dxf layer is already saved to a shapefile with the needed crs. The layer has a large offset and nothing happens when I set the crs to the ...
1
vote
2answers
26 views

Units raster proximity

I aim to calculate the average district-specific proximity to river in India by using the proximity (raster distance) function and the following data here and the GADM India data (level 2 for ...
1
vote
1answer
47 views

Do not show a point symbol for a point if closer than nn meters to another point in same layer

I have a layer consisting of points (big stones), and there are too many points to be able to show them all in the scale I am using in my print composer. What is the most efficient, and preferably ...