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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Bind polygon centroid to polygon attribute data

I am trying to bind a dataframe containing polygon centroids to the polygon attributes. Here's what I've done so far to create the centroids: library(rgdal) library(PBSmapping) library(maptools) ...
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Finding coordinates of raster centroid? [duplicate]

How do I find the coordinates of the centre / centroid of a raster? I have tried Zonal Geometry but this does not give me the coordinates. I need to find the centroids of two rasters and create ...
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936 views

How to compute weighted centroids in PostGIS?

I have a group of points and each point has an associated count value. How can I calculate the centroid of the group weighted by the values associated to each point?
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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
604 views

Is there a method in SQL Server (2008 or 2012) that will return the equivalent of the Esri LabelPoint for geometry?

I'm looking for a method that is equivalent to the Esri LabelPoint for SQL Server Geometry (or fairly close). Does it exist by a different name? Or is there an after-market implementation? I found ...
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How do I convert longitude & latitude to a 3d (geocentric x,y,z) coordinate?

I'm interested in finding the centroid of a point cloud. I understand that to do this I need to convert latitude and longitude values to 3d coordinates, average them and then convert the resulting ...
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QGIS weighted centroid of polygons with weights from raster layer

I am a total novice with GIS and using QGIS as that is what is available to me. I have a vector layer of polygons (about 3500) and a raster layer of light intensity. What I'm working with looks like ...
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157 views

mean coordinates and measurement of distances

I am trying to find a location that minimises the total distance to a series of points, and compare it with the distance to an existing location. I used the QGIS tool mean coordinate(s) to calculate ...
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Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
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1answer
574 views

How to get projected centroids in QGIS?

I am trying to get a centroid for several polygons on a global scale, in a way that it would correctly represent the common centre of all the polygons, taking Earth's curvature into account. The ...
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83 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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126 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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384 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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Ordering polygon centroid points in a row(s)

I have a image from a field, where I converted the plants to polygons, and then I found the centroid of those polygons (attached image). The numbers displaying on the image are the FID numbers. I am ...
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Qgis creating point within complex shapes (with holes) [duplicate]

I'm looking for a tool to create a point in every polygon, that will be placed in the polygon. these are complex shapes with holes. the point must not put in those holes! the "plugin RealCentroid" ...
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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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Automating calculation of distance between zip code (centroid) and address within one line of data? [closed]

I have a large data set of federal contracts which includes two pieces of spatial data per entry (or line): the zip code in which the project took place and the address of the contractor. I am ...
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Finding centroids for icosahedral gnomonic projection?

I've been trying to create an icosahedral gnomonic projection, like this example by Jason Davies or this one (the Fisher projection). The method that I initially used was using the centroid of each ...
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1answer
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OpenLayers: How to get *real* centroid of a Line Geometry/Feature?

I have declared a line geometry as: var lineString = new OpenLayers.Geometry.LineString([source,target]); then I am trying to get the centroid of this lineString as lineString.getCentroid(). But ...
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Is it possible to query a MySQL database using the results from map.getBounds() with Google Maps API v3?

I have a MySQL database that contains a large number of polygons, one for each district on a map. They are all quite complicated and it's unrealistic to simply load them all at once. I've looked into ...
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How to select centroids within buffer range?

I want to select the red circled centroids. These centroids must be within the blue buffer.
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703 views

How to find multiple centers of gravity?

Say I have a number of customers in a geographical area, marked "c": Each customer has a Lat/Long. I would like to find x number of points, in the same space, that best serve the customers, ie. they ...
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445 views

How to select centroid of multiple nearby points with same attribute

This question is very similar to #131823, that is not solved yet. I want to merge several points like bus stops into one single point in the centroid of all selected points. The bus stops have a ...
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QGIS polygon centriods - How are they created?

I have been using QGIS to analyses spatial data and I created polygon centroids with the vector geometry tools. Now for a report I have to explain how these centroids were created. I have not been ...
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Combining different geometry types into same feature class?

I've searched the question in this blog. Maybe I don't use the right words but anyway my problem is not present in any post so I'll try to explain my question by opening a new one. I have a polygon ...
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Find polygon centroid with Python

I'm using ArcGIS 9.3 to find centroid of some polygon features. I'd like to do this in Python, but so far I can only find solutions with VBA. Can anyone provide some leads here?
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1answer
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Centroids highest density areas

Is there a way to find the centroids of highest density areas in the density raster (red areas in the figure) created with the Optimized Hot Spot Analysis in ArcMap10.3. Theoretically I think I should ...
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1answer
101 views

Controling polygons centroids alignment in QGIS?

I am using Polygons Centroids feature in QGIS and it does an amazing job. My goal though is to set the points on the left side of the polygon and not in the center. Is there a way to control the ...
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1answer
212 views

Find centroid of disolved buffer zones

I've put a 20m buffer on all of my points (144,000 observations), dissolving all overlapping buffers. How do I then take the centroid of the dissolved buffers in QGIS? I want to reduce all ...
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1answer
159 views

Positioning labels in center of clipped polygons?

I am using ArcMap 10.1 and would like to label a polygon layer that i have clipped. It appears that the label is set for the geometric center of the polygon that falls outside of the clipping.
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Calculate The Minimum Distance from Polygon Centroid to Edge

I am looking to calculate the minimum distance from the Center of a polygon (A crescent shaped polygon would have a center inside the polygon) to its edge. I have parcel data and I am trying to ...
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2answers
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Formula to get polygon centroid

I need to compute the centroid position of an irregular polygon with lat and lon coordinates in Java. Which formula should I use to correctly compute a centroid?
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1answer
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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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1answer
42 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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1answer
46 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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1answer
113 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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1answer
945 views

How do I find the centroid of each patch in a raster?

I am trying to get the centroid of a several areas in a large raster data set. The output needs to be raster format, with one pixel representing the center of each patch, in the same resolution as ...
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3answers
355 views

Buffering points bounded within polygons

I'm using arcGIS 10.1 on an i5 win7 machine with 16g RAM. Not a xeon but have never had big problems even with large datasets. Here's what I'm doing: I have point data representing locations within ...
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1answer
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How to find polygons centroids? [duplicate]

Possible Duplicate: Get list of coordinates for points in a layer? Sorry for another basic question - my map is almost done but now my boss wants me to enter new outbreaks (that we don't have ...
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1answer
131 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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1answer
321 views

How to use ST_Contains() with ST_ClusterWithin()

I need to write a spatial query which will return centroids of clusters which are within a bounding box or polygon. The query I have now is: SELECT ST_NumGeometries(unnest(ST_ClusterWithin(...
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1answer
171 views

Calculating center of custom tiles?

Problem How to calculate center of each custom tile as a point (x,y) or (x,y,z) where z is zoom level, in a projection: EPSG:3857? What I know about the tiles Originally they are served as TMS They ...
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1answer
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Distance to nearest hub output not correct

In QGIS 2.6, I'm working with two point layers: center of the population per census tract and stores that accept food stamps. I'm using "distance to nearest hub" to calculate nearest food stamp outlet ...
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1answer
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Drawing routes through centroids

According with this link http://postgis.net/workshops/postgis-intro/advanced_geometry_construction.html I'm creating lines that describe routes. I have a table stopcentroids4 like in figure with the ...
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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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332 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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235 views

QGIS : How to calculate centroid on polygons with holes

I try to compute the centroid of polygons with holes on qgis. I did not manage to do it directly, I had to make a conversion to convex hulls before extraction. I crashed my pgsql server trying to ...
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347 views

Centroid of the equator and a point

Suppose I already have a way to compute the centroids of different geometry types: Points (arithmetic mean of Cartesian coordinates). Linestrings (polylines) (weighted mean of segment mid-points in ...
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2answers
4k views

How to use centroid option in Field Calculator in QGis

I want to use Centroid option in field calculator in QGis .How to access it?
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806 views

Find centroids of rows with Multipoint Geometry

I wish to find the centroid of a set of given points. The points will be rows of my SpatiaLite database and have Multipoint geometry. I checked the SpatiaLite manual but the ST_Centroid function I ...