I want to convert polygons into points using QGIS.
I know how it's done in ArcGIS Desktop.
How can I implement it using QGIS?
QGIS Geometry Conversion – Converting Polygon into Single or All Points
geometry-conversionpointpolygonqgis
Related Solutions
QGIS ships with OGR which has a method GetEnvelope():
# Returns the geometry's extent as a list (minx, maxx, miny, maxy)
<geom>.GetEnvelope()
You can easily use it from within your QGIS python console. If you want to convert those coordinates into a shape? Have a look at my answer to this question for some info on modules which will help you turning this list into a vector file. There you find also further details and some helpful links.
Convex hull - as mentioned by Kazuhito - is one option, but - depending on the cluster shape - you will get more appropriate polygons using concave hulls, for example implemented in ConcaveHull plugin.
Best Answer
You can do the "Centroids" in QGIS using: