Edge Bundling is a technique used generally when there is a visual clutter which appears when a graph has a large number of nodes and links. This technique is used to reduce the clutter.
Visualizer support two edge bundling methods: force directed and hierarchical edge bundling.

Force directed edge bundling

This method of bundling is efficient in terms of visual result. Certain Number of parameters are decisive in the clarity of result, namely, stepDampingFatcor,iterationsPerCycle,cyclesNumber,compatibilityLimit, springConstant, startingStep, starighteningAmount, numberOfSubdivision.
the initialization of this parameters for a graph with around one thousand links is as follows:

protected function getParams():Object
{
var params:Object=new Object();
params.numberOfSubdivisions=1;
params.straighteningAmount=0.1;
params.startingStep=4;
params.springConstant=1;
params.compatibilityLimit=0.4;
params.cyclesNumber=6;
params.stepDampingFactor=0.2;
params.iterationsPerCycle=50;
return params;
}

The application of force directed edge bundling is as follows:

protected function bundleLinks():void
{
visualizer.performComputationalEdgeBundling(EdgeBundlingConstants.FORCE_DIRECTED_EDGE_BUNDLING,getParams());
}

The performance of force directed edge bundling algorithm is shown in this screen shot:

Hierarchical edge bundling

Hierarchical bundling is another edge bundling technique supported in visualizer. This algorithm is less complex then ForceDirectedEDge but it can only show performance in huge graph with a number of edge greater than 1000.
It can be applied as follows:

protected function bundleLinks():void
{
visualizer.performComputationalEdgeBundling(EdgeBundlingConstants.FORCE_DIRECTED_EDGE_BUNDLING,getParams());
}

The performance of hierarchical edge bundling is shows in this screen shot with a graph containing around three thousand edges: