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Geographic Information Systems

Questions tagged [vector]

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A coordinate-based data model that represents geographic features as points, lines, and polygons.

1,331 questions
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2
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1answer
60 views

Retrieving lines radiating from point with v.select in GRASS GIS 7.6

I am attempting to select lines that radiate from a point using v.select in GRASS GIS 7.6 (also tested with 7.4.4) in Windows 10. I start out with 48 lines radiating from a point every 7.5 degrees. ...
0
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0answers
14 views

Loading layer with QgsVectorLayer in standalone PyQgis 3

I can't seem to figure out why my layer won't charge in QGIS. After reading many topics, it seems to be linked to the prefix path. However changing this, does not seem to work (I tried around 10 ...
1
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1answer
57 views

Automatic correction of many topological errors in shapefile?

I have a database with topological error. In particular I have an overlay of polygons. I would like to correct these errors. I thought to use an automatic procedure since I have a lot of errors. I ...
0
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1answer
28 views

Correcting topological errors in QGIS?

Using the topological corrector inside Qgis I have identified overlapping polygons. My situation is represented into this image My polygon of interest is located below another polygon (the red ...
1
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1answer
22 views

Is there an alternative function which does the same thing as clip raster by masked layer on QGIS?

I am having some technical problems with the clip raster by masked layer and I faintly remember using a different method a long time ago for a similar problem. Anybody familiar with another function?
1
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0answers
32 views

Vector tile generation

I have a full planet imported in PostgreSQL with imposm3. What is the best way to generate vector tiles (MVT in .mbtiles) from PBF/PostgreSQL with maximum hardware utilization (distributed generation ...
3
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2answers
80 views

Creating building shadows in QGIS?

Can anyone think of a simple way to create a polygon to represent building shadows? I have a shapefile with height information for the buildings and I want to create a simple plan looking like the ...
5
votes
2answers
107 views

Splitting polygon using another polygon in QGIS?

I have two polygon layers (yellow and orange in the attached image). I am wondering if there is a way to get a count of the number of isolated areas that the orange polygon has divided the yellow ...
1
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2answers
69 views

Problem with intersecting lines over a polygon layer in QGIS

I have a shapefile with lines (a road network) and I want to intersect it over a polygon layer in order to finally have a polygon layer (each cell has an ID number) with the intersected lines for each ...
1
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0answers
37 views

Converting vector in NED to ECEF? [closed]

I have a geodetic WGS84 position, lat, lon, alt, and direction cosines from the same point, uN, uE, uD. I'm brand new to geodetic/ecef conventions. How do I take a vector (say, a unit vector with ...
1
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1answer
32 views

Python: Convert shapefile to GeoJSON whilst stripping and renaming fields

I'm writing a Python script to convert shapefiles into GeoJSONs but I would like to remove many of the fields as they are redundant and rename the ones I am retaining. Here's an extract of where I ...
2
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1answer
84 views

3-D Terrain effects for vectors in QGIS?

I'm a bit new to QGIS, and making a few maps of roads through mountains. I'm looking to have a 3-D effect within my 2-D map. I got a DEM, made a hillshade, and blended a basemap over it. Nice ...
0
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2answers
37 views

Reclassifying vector polygons based on text string to integer using Python Parser of ArcGIS Field Calculator?

So I am trying to reclassify a text string by searching for bits of strings and converting those strings to an integer value in a new field within the field calculator. e.g. I want to find all values ...
1
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1answer
44 views

Calculating areas of polygons that match with overlapping raster threshold value?

I have a polygon of districts (districts.shp) and a raster of rainfall (rainfall.tiff). I want to calculate the area of each district that saw rainfall greater than various numbers. I'd like to ...
0
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0answers
21 views

Can only select certain polygons

I have only one vector layer on my map, and it's not letting me select some polygons. For instance, this is what happens when I try to select a certain polygon (the yellow outline with the blue star ...
1
vote
1answer
53 views

Map based on highest percentage from different variables

I've the 8 social classes (see under) for +- 900 polygons. I would like to create a new column that keep only name of the main social class for each row (based on the percentage). After that I would ...
0
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2answers
71 views

Seeking tool to work out overlap between two polygon layers and their statistics using QGIS

I have two polygons in QGIS. One is a land-use map, which polygons that include different types (forest, agriculture, urban etc). I also have a vector polygon that represents a flood extent. I want to ...
1
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0answers
65 views

Fixed distance buffer is oval in QGIS?

I want to create circles of diameter 20m in QGIS. I create a point and then use vector - geoprocessing tools - fixed distance buffer. My problem is that the size is crazy and worse, the shape is not a ...
0
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0answers
43 views

Computing Moran's I for vector data in GRASS

Does GRASS allow for computing Auto-Correlation using Moran's I statistic from vector files. GeoDa and ArcGis can do this. But seems grass lacks this functionality https://grass.osgeo.org/grass76/...
3
votes
1answer
62 views

Fixing self-connect polygon in QGIS 3.2

I'm trying to clip a soil map layer and am getting invalid geometry that affects my clip result. The problem appears to be a self-intersecting polygon. I've tried using the 'check geometries', and ...
0
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2answers
83 views

How to convert multiple shapefiles of different geometries into a georeferenced raster

I have multiple shapefiles extracted from OSM vector data, as shown in the image bellow: How can I render this into a raster of a specified resolution? Is there a way to do that using QGIS or ...
0
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3answers
76 views

Converting raster pixels to vector cells?

Is there any way to convert raster pixels to vector cells? I mean each pixel to a polygon. I tried the SAGA tool 'Raster values to points' by choosing cells option instead of nodes option. As a ...
0
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0answers
31 views

Clipping features with the attributes of another feature

I have a vector polygon for a catchment which contains numerous subbasins. In addition, I also, possess another vector polygon showing the impervious areas of the catchment. What I want to do is ...
3
votes
1answer
76 views

Buffer with unknown distance by adding numerical values of a column until a maximum

In my QGIS project, I have a vector of polygons representing slope zones around an archaeological site and I want to calculate the area which is necessary to supply the ancient population with a ...
-1
votes
1answer
62 views

Summing amount of vector points in area of another vector using Google Earth Engine?

So I have 2 layers each are both vectors and not images. here the link: https://code.earthengine.google.com/e7aec6c9683ed40a959a01a7ed5dd31f I have written some basic code to display the data which ...
0
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0answers
72 views

Creating memory layer with .png image using PyQGIS?

In Aligning Raster and vector layer using PyQGIS when they do not match?, someone gave a solution for creating a point memory layer to correctly align a raster image with a vector. I am wondering ...
2
votes
3answers
130 views

How can I save a vector layer to memory (or is there a reason QGIS doesn't allow this)?

It's impressive how many different vector file formats QGIS (using ver 3.6.0) allows me to save a layer as: But as far as I can tell, QGIS doesn't allow me to save a vector layer to memory. In my ...
1
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0answers
118 views

PyQGIS raster image shifted from vector shapefile

I previously asked a question about my raster image being larger and shifted over from my vector image here, but now I realize that the raster image is only shifted to the left and up from the vector ...
1
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0answers
43 views

Storing a large amount of vector layers on PostGIS

I'm developing a web application where PostGIS will be used as a vector tile server backend to serve mvt tiles. For each user of the application at least one vector layer will be created. So, ...
2
votes
1answer
63 views

PyQGIS code for Merge Vector Layers

I've been trying to automate the merge vector layers via PyQGIS but I can't seem to get it right. This is my code: import os import processing loc = r"C:\Users\loc" os.chdir(loc) shapelist = os....
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0answers
61 views

Can relation reference in QGIS and QField be used to fill stochastic matrices?

I am a novice GIS user and am just seeing the potential for relations in my work. A problem I've come across and would like a solution to it. I have two stochastic matrices (risk matrices) that ...
4
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0answers
46 views

Referencing an output in an expression in process modeler

In the process modeler, I'd like to reference an output of a previous step as one of the parameters of an algorithm. In this case, the previous step was clipping a large raster and I want to use the ...
1
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2answers
63 views

Selecting latest date with QGIS field calculator?

My shapefile contains columns like "Street", "number" and "date". What I want to do is, to find the latest date (where we have done house services). If we have 2 dates for one house number ("number")...
3
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2answers
75 views

QGIS how to sum a certain vector field inside a polygon and populate a field in the polygon?

I have a polygon with vector point civic addresses inside it. Each civic address has a different number residence. I want to sum the total number of residence inside that polygon and it populate a ...
0
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0answers
30 views

QGIS 3.4 (mac) std::bad_alloc error

I get the above error when trying to add a new raster or vector layer. Does anyone know how to correct it as the resulting projection is nowhere near where I need it.
0
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2answers
69 views

QGIS Hex grid with the shape of vector

I'm trying to make a hex grid net with the shape of polygon. Unfortunately, the grid net is in the rectangle shape (see the screenshot). Any advice how to do it?
2
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2answers
46 views

Unite several polygons that share boundaries in QGIS

My study zone is in the middle of two geologic maps with two different shp files. Is it possible to remove the boundaries of the polygons between these two maps that are created at the union of ...
2
votes
1answer
48 views

average weighted value by region with use of Voronoi in Qgis

I have a vector layer of Voronoi polygons. This layer has three columns -longitude, latitude, Z-value. I need to cut polygons by mask of administrative area and then I need to calculate average-...
0
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0answers
12 views

Get visible polygon form one point (visibility graph with one point)

Problem I would like to get the visibility of one point in regard to a polygon layer. E.g. which island can I see from the beach. What I found It's possible to get a visibility graph via Grass v....
1
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0answers
176 views

Error in reproject vector file using GeoPandas

I have a vector file (in this case shp file) and I read it with GeoPandas (gpd). vector_folder = r'C:\poly' vector_file = 'poly.shp' df = gpd.read_file(os.path.join(vector_folder,vector_file)) df ...
1
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2answers
70 views

Calculate the percentage of a Line passing through Polygons

I have a polygon layer of a region (100% coverage, no overlaps) and a line layer in the same region. I want to calculate for each line to which percentage it crosses certain polygons. I have seen ...
2
votes
1answer
80 views

Creating new lines based on another line feature and point feature using QGIS?

I have line layer (roads) and point layer (milestones) and I need to create a new line layer based on roads layer, where the start and the end points will be milestone points. Can you advise me some ...
1
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1answer
147 views

QGIS 3.6: Vector “Polygons to Lines” missing

I use the tool Vector-->Geometry Tools-->Polygons to Lines all the time. It is in the menu up until 3.4. In 3.6, that menu item is no longer available. Where did it go? Is there another way to do ...
1
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3answers
64 views

Calculating the shortest distance coordinate to vector layer

I want to calculate the nearest distance from each coordinate in a vector layer containing more than 17 000 coordinates to another vector layer. I tried the GRASS v.distance tool but it gives the ...
4
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3answers
438 views

QGIS split vector layer gives me GPKG files but I need shp files

QGIS 3.6.0 I am new to QGIS software and not very technical on its deep workings. I am trying to split a .shp file using split vector layer. I need .shp file outputs but it auto creates .gpkg files. ...
1
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0answers
132 views

Does any version of QGIS support GDB 10.5?

Does any version of QGIS support GDB 10.5? I have a GDB 10.5 file that I need to open in QGIS and I can't. I'm using QGIS 3.6. The file is named Virginia_Parcel_Dataset_2018Q4.gdb -- it can be ...
0
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0answers
57 views

ArcGIS: Train Support Vector Machine Classifier on a Segmented Raster

I have a raster (.jpg) which I have segmented utilising Segment Mean Shift to smooth out JPEG artefact (aim is to classify it as accurately as possible for conversion into vectors). START .JPG Input ...
0
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1answer
20 views

How can I keep the minimum when converting from shapefile to raster

I have a shapefile that I am trying to convert to raster. The shapefile has overlapping polygons. I would like to keep the minumum value of these overlapping polygons when converting to raster. ...
1
vote
1answer
96 views

How to make a rectangle of an exact size/aspect ratio in QGIS?

Is there any way in QGIS to make a vector layer with a rectangle of an exact size or aspect ratio? Ideally, it would be nice if the rectangle from extent tool could be limited to a set aspect ratio, ...
1
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0answers
106 views

Vector Rasterize Error

I am running QGIS 3.4.4 With GRASS 7.4.4 and I get an error while rasterizing a vector layer and I don't know why. The same error pops up while using GDAL->Rasterize(vector to raster) and while using ...

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