Merge point features within a given radius

Question

I have a file in QGIS with 5000 points. Some of the points are really close to each other (5m). How can I cluster the point features to one point feature if they are within 5m? The new points should be centroids from the given points.

How would you like to deal with a situation where you had 50-60 points that were each within 5 m of another point, but spread out over, say 200m overall? Should they then all be merged to a single point? — Simbamangu, Nov 11 '13 at 10:55
Do you want to delete the points or overlay them atop one another? — Simbamangu, Nov 11 '13 at 11:58
Does merge the point features to one point feature mean calculate a new (barycentric) point feature or discard all the points except one on some basis? — Antonio Falciano, Nov 11 '13 at 14:41
@afalciano I want to create the centroid of the point features, like the way you described in your answer. — ustroetz, Nov 11 '13 at 17:58
@Simbamangu It is not really the case in my dataset, that the points are spread out over 200m and are within 5m distance. — ustroetz, Nov 11 '13 at 19:18

Antonio Falciano · Accepted Answer · 2013-11-11T10:04:26.790

One possible approach consists in the following steps:

draw a buffer of 5m around points;
dissolve the buffers which overlap;
calculate the centroids of dissolved buffers.

You can choose the tools with which you're more comfortable.

Example
For instance, using GDAL >= 1.10.0 compiled with SQLite and SpatiaLite you can calculate the buffer around your points.shp:

ogr2ogr buffers.shp points.shp -dialect sqlite -sql "SELECT ST_Buffer(geometry,5) from points"

Then, calculate the clusters (dissolved buffers):

ogr2ogr clusters.shp buffers.shp -dialect sqlite -sql "SELECT ST_Union(geometry) from buffers" -explodecollections

Finally, calculate result_points.shp:

ogr2ogr result_points.shp clusters.shp -dialect sqlite -sql "SELECT Centroid(geometry) FROM clusters"

score 1 · Answer 2 · answered Nov 11 '13 at 11:28

Have a look at this tutorial: http://qgis.spatialthoughts.com/2013/04/tutorial-nearest-neighbor-analysis.html

Compute a Nearest Neighbour Analysis for your dataset
Add the resultant table into QGIS and join it to your dataset
Export your data into Excel and Sort/Filter it by distance.
Select all your data rows where the distance is <5 m
Select Data -> Delete duplicates
Import back into QGIS

Where any points are within 5 m of each other, this simple process will remove one and keep the other!

Merge point features within a given radius

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