Questions tagged [centroids]

In geometry, the centroid, geometric center, or barycenter of a plane figure or two-dimensional shape X is the intersection of all straight lines that divide X into two parts of equal moment about the line. Informally, it is the "average" (arithmetic mean) of all points of X. The definition extends to any object X in n-dimensional space: its centroid is the intersection of all hyperplanes that divide X into two parts of equal moment.

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41 views

How do I create centroids inside polygons in Python?

When creating centroids from polygons, ArcMap has an option to placing the centroids inside (within the bounds of) the polygons. I am attempting to create centroids in Python. I have tried: df['...
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21 views

Determining the centroid of the thickness calculation used in Zonal Geometry

I have a need to determine the coordinates at the centroid of the "deepest" point within an irregular polygon feature. I have done some researching and found that Zonal Geometry calculates ...
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Cut linestring segment at centroid in PostGIS

In a table of linestring three segments are connected. first--second--third could Postgis generate the centroid of second segment and merge first and third at center? Is it possible? first--...
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Get longitude and latitude from a shapefile with Leaflet in R

I've been trying to map with leaflet to add addCircles() but my shapefile doesn't seem to have the latitude lat and longitude lng parameters so I got the centroids for each city as is the code below ...
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42 views

Distance Matrix between centroids QGIS

I'm using QGIS and I would like to measure the distance between the centroid of King County in the US and the centroids of all other US counties. I have imported the shapefile and I have executed the "...
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46 views

Calculate irregular polygon center-point that falls within the polygon boundary

I have an SDE.ST_GEOMETRY polygon FC in an Oracle 18c/10.7.1 geodatabase. I can calculate the X and Y of the polygon centroids using the SDE.ST_GEOMETRY ST_Centroid function: sde.st_x(sde....
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Find centroid of a set of points [duplicate]

I have a set of points in 2 dimension plan : A(x1,y1), B(x2,y2), C(x3,y3) .... How can I know which point of these points (A,B,C, ...) is the centroid of the other points
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79 views

Creating ellipse with SatScan output using QGIS

I need to use QGIS to create an ellipse employing a SatScan output with information on spatial risk clusters for the occurrence of an. The output contains the coordinates of the centroid point of ...
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105 views

Finding the centroid of a merged polygon using shapely function

I have a polygon shapefile and I want to find the centroid of the polygon, and output the centroid as a new shapefile before I geocode. How I should do this with Python functions shapely and Fiona and ...
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47 views

Workaround for Mean Coordinates in graphical modeler

I am searching for a workaround to build mean coordinates in graphical modeler since I have noticed a bug which I have reported here: https://github.com/qgis/QGIS/issues/35385 Basically, I just need ...
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Find one centroid instead of multiple centroids?

I'm trying to find the centroid (center of mass) for several IUCN species range maps. Using the code below I've run into an issue in R. library(rgdal) library(rgeos) shp <- readOGR("/Documents/...
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Create centroids from point layer based on unique field names

I have a point layer in QGIS, which I want to filter by attribute values of a specific attribute column. For each unique attribute value, a centroid should be calculated from the respective features. ...
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Difference between grid and its centroid

Recently I was download GPCC gridded precipitation data. I plot them on Matlab and it gives me pixels. then I tried to plot them on the ArcMap and saw there are lots of points instead of pixels. What ...
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52 views

Generate N polygon centroids based on attribute in QGIS

I have a number of polygons with an integer value in a field. I would like to create N number of centroid points for each polygon where N corresponds to the value in the polygon's field. So sort of ...
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80 views

Auto-generate Grid Reference for Point and Polygon features within existing Shapefile, QGIS

I have various point and polygon layers (shapefiles) which I use regularly in QGIS (3.6.3), and often need to work out their location as an 8 figure grid reference (British co-ordinates, EPSG-code ...
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101 views

Centroid of multiple polygons based on value in attribute table

I have a (polygon) shapefile with multiple zones. Now, I would like to calculate the centroid of groups of these zones. The zones have to be grouped based on a value in the attribute table: AreaNr ...
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Creating convex hull by expression by aggregating points

I would like to recieve the centroid of a convex hull of a group of points in a layer, grouped by its name. This needs to be done by expressions, available in QGIS 3.4. E.g. I have this list of points:...
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338 views

QGIS Point on Surface

As far as I can tell, the option to "Create point on surface for each part" in the QGIS Centroid tool is not returning the correct geometry when activated in QGIS (version 3.8.1-Zanzibar/GDAL v 2.2.3 ...
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198 views

Get midpoint of SDE.ST_GEOMETRY polylines?

I have a polyline SDE.ST_GEOMETRY feature class in an Oracle 12c geodatabase (10.7.1). I want to create a view on the feature class that has X and Y columns that contain the coordinates of the ...
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100 views

Getting polyline midpoint coordinates using ArcGIS REST API

I have an ArcGIS 10.7.1 feature service that integrates polyline GIS assets to a work order management system. In the work order management system, I want to retrieve the midpoint coordinates of the ...
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60 views

PostGIS - How to extract polygons in a rectangle by their centroid?

I'm new to PostGIS and I'm amazed what can be done with it! Currently I'm running a query from a large database where I need to split the extracts into smaller chunks so that I'm not bouncing at the ~...
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Calculate centroid of points (group point) [duplicate]

I am new to PostGIS and I need to calculate the centroid of a group of points that have a cluster identifier (id_cluster). I need to get the latitude and longitude of the cluster centroid.
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51 views

Speedup function to calculate distance from centroid of building to river segment in PostgreSQL

I am trying to measure the distance from the centroid of a building to a river segment using the following function. CREATE OR REPLACE FUNCTION river_foo_mapper () RETURNS trigger LANGUAGE plpgsql AS ...
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3answers
101 views

Finding coordinates of centroids?

I have a few thousands of polygons, which I found the centroid for each one of them. Now I want to find the coordinates of each centroid. But for some reason the x and y columns are empty and I don't ...
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36 views

Real Centroids plugin QGis 3.4.4 Inavlid Geometry?

The plugin gives on a specific feature the following error message: "Invalid or empty geometries found". Is the following topology not supported?
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1answer
76 views

Spatial Join Polygon to Polygon with Centroids Inside features

I have a parcel feature class with +5M features. I want to spatially join it to a feature class of regions to check if the regional code matches that in the parcel data. I've tried using "have their ...
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75 views

Making path between polygon using QGIS?

I am trying to draw a line (vector layer) of a certain length that that tries as much as possible to dodge the green polygons. Assuming a starting point, is there some sort of line centroid ...
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1answer
169 views

Combining st_snaptogrid with st_centroid and group by using PostGIS?

I have a table of devices, each of them has a field 'location' that is a postGis geometry(Point,4326) I need to operate a GROUP BY based of the placement on a grid, I'd use ST_SnapToGrid and then I ...
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121 views

Displaying a legend for a centroid, simple marker with size overwrite?

I am new to QGIS and can't figure out how to display a legend for the dot size of a centroid, simple marker. The size of the dot is dependent on a value from a CSV linked to a layer map of Europe. I ...
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272 views

Geoserver SLD: How to get CENTROID of result of INTERSECTION?

In my GeoServer SLD I need to place a symbol (particularly a piechart) exactly on Centroid of the result of Intersection of 2 geometry: geom field from my PostGIS table AND environment variable ...
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27 views

How is the Point on surface tool calculated in QGIS [duplicate]

I am interested to know how the Point on surface tool works in QGIS 3. I am choosing to use this rather than the Centroids tool which works of the "center of mass" methodology because this creates a ...
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Creating centerline of river in QGIS? [duplicate]

I made two river bank lines and I want to associate them. I want to make a centerline using two rows as a base. I managed to make the centre line with a lot of work creating several lines from one ...
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66 views

Centroids: Based on travel distance/time and not straight line distances

I am working on a Sales Person Deployment project and quite often come across requests for calculating centroid of a territory where work is distributed across 1000s of ZIP codes. Increasingly we get ...
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151 views

Calculate weighted centroid of a raster layer using GRASS?

I'm trying to calculate the weighted centroid of some raster layers I have, which are basically patches of positive values in a sea of null values. I know I could convert thoses patches to binary ...
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38 views

NHGIS census files get lat/lon from polygon

I've never worked with shapefiles before and I'm having a lot of trouble with something that I think should be pretty simple. So I have the census tract files from NHGIS for 1980 and the structure ...
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45 views

How to compare centrality of points in different shaped and sized polygons

Suppose I have several polygons of varying shape and size, each containing a single point. I want to compare the centrality of each point, and determine which point is more central to its polygon. I'm ...
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70 views

Calculating centroid for polygon layer with several features?

I need only 1 centroid point for the whole layer (more than one polygon) instead of 1 centroid point per feature that you get with the menu -> Vector -> Geometry tools -> polygon centroid tool. Its ...
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1answer
312 views

Centroid value extraction of Landsat image collection in Google Earth Engine

I have an NDVI collection wich I have created from the combination of different collections Landsat5 and 7. How can I exctract the NDVI values of the centroids of each pixel, of each image from my ...
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71 views

Using centroid point to generate polygon using ArcPy? [closed]

Is this possible to generate polygons from points (which are centroids of future polygon)? I got shapefile with ~250 points + they have got two attributes: length and width. I don't need complete ...
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2answers
82 views

QGIS Rasterize PolygonZM

I have a triangulated DEM PolygonZM shape and would like to Rasterize it in QGIS (3.2). I couldn´t find an option to use the geometry´s z value so i tried to create a field and calculate the centroid´...
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1answer
158 views

How do I center a polygon on specific co-ordinates?

I need to place a set of polygons onto a set of points, so that each polygon is centered on its corresponding point - any ideas? In MapInfo I can just manually edit the co-ordinates of the center, but ...
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235 views

Is there a way to create pixel centroids inside polygons with PostGIS ?

I am trying to find a solution to do the function of the QGIS-tool 'Generate points(pixel centroids) inside polygons' in PostGIS. In the picture below you can see the output. Is there a way to do it ...
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212 views

Raster centroid and relationships with geoTIFF

I have a list (s) containing information on the probable locations of many animals in South America. For example, this is the type of stored information and what it looks like when plotted for the ...
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1answer
518 views

Spatial Join In PostGIS where centroid of a polygon is inside another polygon

I have two overlapping polygon layers as shown in figure below. One with small grid polygons and another with a large irregular polygon. I want to join them such that attributes of the large polygon ...
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0answers
470 views

Finding center of circle given three points?

I have been trying to solve this problem for quite some time, but can't find a good solution. Given three sets of geographic coordinates how can I calculate the center point. By "center point" I mean ...
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1answer
98 views

PostGIS Centroid coordinates (E, N)

I would like to add two new columns in the table (E, N), fill in the coordinates of a polygon centroid using PostGIS SQL code and have the column upadated as soon as I save the edit of a drawing in ...
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250 views

Polygon Centroids working for only some Polygons in PyQGIS?

I have a building Layer(Full of Polygons).I want to get centroids of polygons and save them as point layer.I am using python console within Qgis 3.0. I have tried below code.I got my Centroid Layer(...
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212 views

R sf extrapolate grid from centroids

I've got a grid/raster in R that is represented as centroids of the grid instead of polygons. I am trying to merge that with points. library(sf) nc <- st_read(system.file("shape/nc.shp", package="...
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1answer
657 views

Real centroid plugin QGIS3

I am looking to use realcentroid where I'm assuming it puts all points within the polygons rather than the tool in QGIS Vector -> geom -> centroid tool, which in my result some bendier polygons have ...
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2answers
521 views

Calculate centroids using PyQGIS

I am trying to calculate the centroids of polygons using PyQGIS. When I calculate the centroids with the interface (Vector --> Geometry Tools --> Polygon Centroids) everything works out. However, I ...