Visualize metaballs
8 May 2009
Following the article Nodes groups visualization I was trying to implement this work in the new (very) experimental 0.7 version, just for fun. The purpose of this Potatoes module is to enable users to highlight group of nodes in a network.
When clustering (i.e. grouping) nodes, it is useful to leverage group perception on the network visualization. For instance with SNA (Social Network Analysis) it is a good way to display communities and better see interactions between them.
However it is a difficult problem, both for a software designer and a developer. There is no perfect way to visualize groups when the number of them increases and when they starts to hide and blend each other. This problem appears especially when using convex hulls solution. The presented solution belongs to implicit surfaces systems, also called Metaballs. I found the visual result very precise and beautiful, some qualify it organic. Unfortunately it costs much more resources than hulls to calculate these potatoes and may be applied only on small graphs.
Here you can see a very good example of this feature.

The following video presents it with movement. A small network is displayed with 3 different groups, one per color. A spatialization algorithm is running and moves nodes according to their links. Metaballs are refreshed continuously when moving.
Gephi – Potatoes work in progress from gephi on Vimeo.
Conclusions of this experimental implementation will guide us for official specification of further Gephi releases. We will implement this functionality for vectorial export but presumably not in the 3d engine.










30 March 2010 at 5:42 pm | Permalink
Is there a tutorial on how to visually create something like this? I’ve got some data that has obvious groupings but would like some instructions on how to get it looking like you have above…
30 March 2010 at 6:35 pm | Permalink
No, this was an experimental feature in Gephi 0.6. We didn’t included because it has too bad performances (lag over 50 nodes), but you may use the convex hulls generated over a hierarchical graphs in Gephi 0.7. We will add some tutorials asap.
30 March 2010 at 6:38 pm | Permalink
You can find resources with typing “metaball” or “implicit surfaces”. Check this as well: http://www.quasimondo.com/archives/000562.php if you’re working with flash.