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Questions tagged [vector]

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

2
votes
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
votes
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 ...
2
votes
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. ...
15
votes
6answers
9k views

Defining layer CRS and avoiding CRS dialog in PyQGIS?

There is an existing Shapefile, which I want to add. At the moment my code looks like: self.iface.addVectorLayer(self.shpFilePath, "Track", "ogr") It works fine, but i want to define the crs within ...
1
vote
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
votes
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
vote
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
votes
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
vote
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
vote
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
votes
1answer
355 views

Aligning raster data to vector data in QGIS?

I'm in the midst of aligning century-old maps (of Paris) to vector data of the modern same: Qgis' Georeferencer tool works fine, but doing the entire city that way is a gargantuan task. Paris hasn't ...
3
votes
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
vote
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
vote
1answer
35 views

QGIS Union erroneously creating gaps

I'm trying to do a union between two Polygon Shapefiles, but when I do Vector > Geoprocessing Tools > Union I have the odd issue where most of it works fine, but some areas are returned in the union ...
1
vote
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
vote
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 ...
3
votes
1answer
372 views

Generating customized vector OSM map files from OpenStreetMamp and other data?

I am looking for a way (e.g. tutorial?) to generate my own customized (offline) maps in OSM format. By "customized" I mean adding data (not just define a region of interest) to an existing OSM map (e....
3
votes
1answer
84 views

v.reclass no output

I want to reclassify a polygon vector and use v.reclass. Feature type: boundary Name of column: LBA Reclass Rule: I use a .txt with the following content: CASE WHEN LBA = 68 THEN 2 WHEN LBA = ...
3
votes
1answer
217 views

Density map of pedestrian paths and footways in QGIS

I need to identify public places within pedestrian areas in London, so I need to calculate the density of both pedestrian links and footways. I have classified my data according to the categorization ...
0
votes
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 ...
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
votes
2answers
532 views

Getting feature coordinates from dynamically loaded layer using OpenLayers?

i want to load the coordinates of a point that is stored inside a vector layer and the vector layer is stored inside a layergroup. I do load the vector layers dynamically to the layergroup "Runs". So ...
1
vote
2answers
584 views

Seeking data source for worldwide urban/statistical areas as polygons?

I am looking for a shapefile (or any format really) that has worldwide coverage of major urban areas / statistical areas as polygons with names. Similar to what the US census Bureau' Core Based ...
7
votes
5answers
9k views

Merge overlapping lines in ArcGIS

I have a polyline shapefile containing a number of lines, some of which overlap. By overlap, I mean that they follow exactly the same path for some of their route, but also have bits that are not ...
9
votes
3answers
20k views

Getting extent of layer in QGIS?

Is there a way to get the extent (bbox) of a vector layer in QGIS? I see that I can update the extent, but I am looking for the actually coordinates of the extent.
0
votes
2answers
70 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 ...
5
votes
2answers
2k views

Empty vector menu in QGIS 3.0.0

I installed QGIS 3.0.0 on a PC with French as default language. After changing the language of QGIS to English, the 'Vector' menu is empty and there is a French 'Vecteur' menu. Any ideas how to fix ...
2
votes
2answers
440 views

Changing vector extent in QGIS

I've been looking for a manner to change a vector extent in QGIS, but it's unsuccessfull! I want change extent because in the past, I had problems to convert vector to raster. I try present the ...
0
votes
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 ...
-2
votes
1answer
240 views

Why don't shapefiles online contain the coastline (country borders)?

I have searched everywhere and Geofabric has the best packages of shps yet doesn't have the coastline of countries. I'm talking about the line that demarcates a country i suppose they are called ...
0
votes
1answer
56 views

Changing unknown coordinate system of raster data to known coordinate system?

I have a set of raster datasets and have created a raster catalog out of them. These datasets should cover specific vector data. I have just realised that the raster as tif data have a coordinate ...
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 ...
3
votes
3answers
339 views

Plotting Geo Points with “by arc centered at” Instructions

A recent Supreme Court decision redefined the legal boundaries of California along the Pacific Ocean: http://www.theverge.com/tldr/2014/12/15/7397085/supreme-court-california-boundaries-map I am ...
1
vote
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
votes
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
3answers
3k views

“Node tool: could not snap to a segment on the current layer” message

I have a strange issue. Editing a layer with node tool I get always the following message: "Node tool: could not snap to a segment on the current layer." This error happens to me even with a fresh ...
1
vote
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
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
votes
2answers
82 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 ...
4
votes
5answers
4k views

How to sum raster image values with vector overlay

I'm new to this and haven't been able to figure out how to do this on my own. I have two files: a raster image of land use data and a vector-based shapefile of my territories. The raster image has ...
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 ...
0
votes
0answers
30 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 ...
0
votes
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 ...
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
vote
1answer
290 views

Aligning Raster and vector layer using PyQGIS when they do not match?

Relatively new to GIS. I've created a vector layer of points based on row/col position of high population density pixels in a raster layer. The layers do not align even though they have the same CRS, ...
3
votes
2answers
2k views

Identify polygon containing point with R sf package

I would like to be able to map geocoded coordinates to a region on a .shp file in R using the sf package. I can load up the map and plot it but I am struggling with the code to return the region for ...
1
vote
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, ...
0
votes
1answer
64 views

How do I get Table from Vector layers for use with joinattributestable

I am attempting to run: processing.runandload('qgis:joinattributestable', layer1, layer2, 'id', 'id', None) To join my tables and output to a temporary viewing layer. layer1 and layer2 are both ...
4
votes
3answers
437 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. ...