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Questions tagged [vector]

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

13
votes
1answer
7k views

How to remove a vector QgsVectorLayer from QGis python plugin

I managed to add QgsVectorLayer in QGIS through a python plugin, for example: vl = self.iface.addVectorLayer(uri.uri(), layerName, self.dbConn.getProviderName()) But how can I remove it?
0
votes
0answers
28 views

Polygon interpolation neighbour average?

I am trying to estimate empty values based on a polygon layer we received from another study. Is there a way to calculate an average value for polygon A based on neighbours B,C, etc that border it? I ...
1
vote
2answers
1k views

Converting from ECEF to geodetic coordinates

I am trying to convert an ECEF coordinate to a geodetic coordinate using this procedure, but I don't fully understand the process. It is prefaced by stating the geodetic parameters {a,b,e,e'} are ...
1
vote
0answers
47 views

QGIS: Fill shapefile vectors with grayscale based on elevation

I am very new to this and feel like this is probably an easy answer, but after days of searching this forum I still am unsuccessful. I have shapefile data with elevation and I want to create a raster ...
1
vote
1answer
266 views

How to create displacement vectors in QGIS using GPS points with different dates?

Is there a way to calculate and visualize displacement vectors in QGIS ? I have DGPS points taken at the same place (ground control points), but their position moved over time as they are located on a ...
0
votes
0answers
65 views

Opening National Land Cover data?

How do I open the National Land Cover data in QGIS 3.0? Attached is an image of the files. It looks like it's an .rrd file.
2
votes
2answers
648 views

How are the coordinates for multipolygons arranged?

How are the coordinates for a multipolygon (i.e. polygon with a hole in it) arranged? Do shapefiles and geoJSON files always save the coordinates for the outer ring first? I'm asking because I ...
-1
votes
1answer
155 views

Get PostGIS geometry data and display it on map using GetMapRequest

How can I get the data from PostgreSQL db and display on map using GetMapRequest? I have done connecting the PostgreSQL db which contains the geometry data. Now I want to redirect that data to map ...
3
votes
2answers
2k views

Cleaning polygon after using dissolve to repair geometry in QGIS?

I'm trying to obtain the boundaries of shapefile, thus to clean the inside as a matter of speaking. While I had expected that dissolve while get me a proper polygon, unfortunately it still has some ...
1
vote
1answer
243 views

Plugin SWAP vector direction doesn't work in QGIS

I've installed plugin Swap vector direction in QGIS. But it doesn't work. I click and nothing. I need to flip lines (22 000 000 lines). In ArcGIS takes many hours and still flipping. I thought ...
2
votes
3answers
5k views

Some Help to select some features from a vector layer

I have a vector layer (kml) that has some point with scientific name of plants and animals, some description of the place where the people saw them and the coordinates. Basically the table associated ...
5
votes
1answer
264 views

Load and apply Style from Postgres in QGIS 3

I want to write a plugin in QGIS3 that changes the style of a vector layer. The styles to be loaded are saved in a postgres database in the table 'layer_styles'. I read here or here , to use ...
1
vote
3answers
354 views

Creating a source and a layer from vector tile features in Openlayers

So I retrieve all my features from a vectorTile layer (PBF from Geoserver), and now I want to recreate a layer by filtering on those features and getting only those that satisfy a request. I ...
2
votes
1answer
165 views

How to merge all layers in QGIS project using 'merge vector layers' within PyQGIS

I am trying to use the 'merge vector layers' tool in PyQGIS to merge all of the layers in my QGIS project into one shapefile, as part of a larger script I am developing. I tried this script, but I get ...
0
votes
0answers
76 views

TileStache serving vector MBTiles

Is this possible? I have D/L vector .MBtiles files from openmaptiles and want to serve them to leaflet via tilestache. This is all in hopes of saving disk space and bandwidth over server straight up ...
0
votes
0answers
32 views

Getting static .pngs from mbtiles file or other sources

My nomenclature may be astray because mapping and GIS is not my domain. We need to be able to serve tiles locally in a structure lik the folder example provided here: https://www.maptiler.com/how-to/...
0
votes
1answer
573 views

Request a WFS layer using OpenLayers

I am new to OpenLayers and GeoServer... can someone please help me to show a WFS layer... here is my code: const vectorSource = new ol.source.Vector({ format: new ol.format.GeoJSON(), url: ...
2
votes
1answer
211 views

Multiple display of vector layer in a QGIS plugin interface

def initGui(self): """Create the menu entries and toolbar icons inside the QGIS GUI.""" icon_path = ':/plugins/cropEt/icon.png' self.add_action( icon_path, text=self.tr(u'...
10
votes
2answers
761 views

What's the batched Refactor Fields tool “field mapping” syntax in QGIS?

In QGIS, there is this nice tool "Refactor Fields" in the Processing Toolbox : Using it on a single layer is fairly straightforward. However, when you plan on using it in a batch mode, one can see ...
8
votes
4answers
1k views

Understanding resolution in vector maps?

I'm developing a vector maps with detailed features such as road edges, cross walks, traffic lights , street lights etc., by using 3D points (x,y,z) without geo-referencing, generated from stereo ...
1
vote
1answer
214 views

Getting data on area where shapefile overlaps raster file using QGIS?

I have attached an image to help explain what I am asking. I want to get the average value of where the heat map crosses over each municipality in the shapefile and export those values into a ...
1
vote
2answers
547 views

How to export vector file in GrassGIS to QGIS

I am using GrassGIS to analyze watershed. I created a stream vector extracted from raster elevation data, how to extract the stream vector file so I can open it using QGIS?
4
votes
2answers
4k views

How to unselect features in ONLY the current layer in QGIS?

How does one unselect features only from a certain layer? I know there's the Deselect features from ALL layers button. But that's extreme. Is there a simple way to unselect features ONLY from (say) ...
1
vote
1answer
41 views

Statistics for point data within each polygon using ArcMap?

I think this is a pretty basic GIS operation but I'm not sure how to do it. I have hundreds of polygons, and within each polygon there is point data (see picture). The point data has a field "Type" ...
1
vote
1answer
238 views

How to calculate the overlap of two polygons in PostGIS

I am trying to calculate the percentage overlap of two vector polygon layers and saving the result as a separate column. The code below is working: CREATE TABLE parcels_all_shapefile_new AS SELECT ...
7
votes
5answers
3k views

WFS to Vector Tiles

Is there, by some miracle, an existing piece of software which is able to convert a (3rd party, GeoServer) WFS feed into vector tiles? In a utopian world, this would happen on the fly, but a download/...
3
votes
4answers
286 views

Calculate length of huge vector lines dataset

I have a MultiLineString vector layer from which I would like to calculate the length. I have tried to calculate the length with the Field Calculator by putting in the expression $length. The ...
0
votes
1answer
96 views

Why does Q-Chainage sometimes offer meters and sometimes degrees?

Q chainage is a plugin which puts regular points on a line vector at regular intervals which you can specify. For a shapefile I've been given (and converted to line vector), it offers me to specify ...
1
vote
1answer
76 views

Mask a Raster layer in QGIS using a vector layer with multiple polygons

I would like to extract statistics from a raster file based on a land cover classification vector file, however the land covers (features) are not contiguous (see pic). In the example below, I would ...
1
vote
1answer
130 views

Only show buffers that overlap geometry

I have multiple sites that are surrounded by a buffer. I also have a layer which corresponds to areas affected by changes. I am trying to filter out buffers that are not overlapped by the change ...
0
votes
0answers
98 views

OpenLayers receive all feature data from Vector (WFS)

I would like to display a Diagram for the data that is received via a WFS. As this data is already displayed on the map, a second request is not necessary. Normally I receive the underlying data on a ...
1
vote
1answer
66 views

What is the alternative of setZoomLevel in vector based map?

It is commonly used to generate map tiles at a certain scale and re-organize them for web map on PC. For example Google map, and Bing map. Then user will use the setZoomLevel(int level) or something ...
0
votes
0answers
17 views

QGIS line editing? [duplicate]

I am fairly new to QGIS, but how do you edit this line? I added line 1-3 and 2-3 and I need to get rid of line 1-2. 1-2 is one part of the large boundary lines connected to each other. Before I delete ...
4
votes
1answer
2k views

Why do layers appear in the wrong order in QGIS 2.2?

I have a problem with in which order my vector and raster layers appear in QGIS. I have raster that I want to be the background of my other layers (vector). I place the vector layers on top in the TOC,...
0
votes
1answer
105 views

Make OpenLayers filter initially empty

I have an OpenLayers vector layer that loads data form service. But it loads all data initially. var mylayer = new OpenLayers.Layer.Vector(null, { "protocol": myWFSProtocol, ...
1
vote
1answer
53 views

Is there a vector format for depicting continuous 2D polygons with attributes?

I'm working within the QGIS environment and looking for a 2D continuous vector attributed editable file format to work with. My goal is to find a vector layer that has different features with no ...
0
votes
1answer
115 views

Using Presence/Absence method in QGIS?

I seek advice for calculating presence/absence of features in QGIS. I have a polygon dataset of boundary outlines and a number of other datasets which I want to compare it against for presence/...
1
vote
0answers
46 views

Area calc gives odd answers [duplicate]

I made a shapefile from a DEM raster of Ethiopia, and I want to find the total area of the shapefile. I have changed the CRS of all files to Africa_Albers_Equal_Area_Conic (ESPG: 102022), and the ...
1
vote
2answers
152 views

Generate Point Layer at Line Intersection

I have a line layer that is actually buffer polygons converted to a line layer. I would like to generate points at all places where 3 or more lines intersect. I would settle for places where 2 or more ...
3
votes
1answer
982 views

How to change layer symbology in QGIS 3 with QgsFeatureRendererV2?

I am updating a QGIS plugin from QGIS 2 to 3 and I am struggling with changing the layer symbology (a single symbol type for a line layer). I would like to have all lines in my layer to have the same ...
1
vote
1answer
1k views

Clipping raster with an irregular shape?

How can I clip my DEM raster in a irregular shape in QGIS? I have used the clipping tool but it only does rectangles I believe.
0
votes
0answers
157 views

Saga difference vector tool

My QGis Difference tool doesn't work really well, it gives me lots of little squigly lines. i read in the link below there is such a thing as a vector diffence tool from SAGA, but i can't find it. ...
4
votes
1answer
307 views

Vector Tiles for NetCDF Data [closed]

I understand that the GeoServer can produce vector tiles in three formats: GeoJSON, TopoJSON, and MapBox Vector (MVT). Moreover vector tiles has many advantages in handling data such as reduced size ...
0
votes
1answer
124 views

QGIS - Split Vector Layer returns empty layer

I'm to split a vector layer by feature with "split vector layer" tool in qgis I want to split the "switchboar" column after I fill the tool I receive the new empty layer Does anybody know why I don'...
0
votes
1answer
146 views

QGIS 2.18 buffer [duplicate]

I'm trying to use fixed distance buffer, and had a few questions. One, what units is the distance being measured in? I assumed meters, but after doing a test run it clearly isn't. And two, what is "...
1
vote
1answer
37 views

Non-destructive improvement of vector layer (shapefile) representing a road network?

I have a QGIS project with some vector layers backed by shapefiles. One of these layers contains all the roads, and I would like to "improve" it: It is organized in a way that each vector feature ...
1
vote
0answers
210 views

How to open memory data with ogr in rasterstats function?

I would like to reuse vector data created in memory in another function called rasterstats (source code, documentation): I have a function that creates vector data: def createPolygons: ...
1
vote
1answer
305 views

QGIS 2.18 Polygonize (raster to vector)

I'm a bit confused about how to use polygonize (raster to vector). Particularly what to put in the field name box. The documentation states that it "Defines the field name in which the attributes of ...
1
vote
0answers
494 views

Using MySQL vector with QGIS?

I have a problem with mysql vector; when I connect to the MySQL table (containing a geometry column), the attribute table is loaded correctly, the map is centered properly but the geometries are not ...
2
votes
1answer
78 views

Styling/labeling specific features in QGIS?

I need to styling/labeling some specific features in a vector layer. I thought I could use the rule-based option in the style/label window with a "field=value" expression if i have only one specific ...