         particleSceneView.scene = scene
     }
 
-    func createParticlesceneNode (particleSet: ParticleSet) -> SCNNode {
+    func createPartcleSceneNodeFromSets (particleSets: Array<ParticleSet>) -> SCNNode {
+        
+        // randomly arrange different ParticleSets on a plane
+        let colorSections = 1 / Float(particleSets.count)
+        var rootNode = SCNNode()
+        for var i = 0 ; i < particleSets.count ; ++i {
+            let hue = CGFloat(colorSections) * CGFloat (i)
+            rootNode.addChildNode(createParticlesceneNode(particleSets[i], zplane: Float(i), hue: hue))
+        }
+        
+        return rootNode;
+    }
+    
+    func randomParticleSet() -> ParticleSet {
+        var particles = Set<Particle>()
+        
+        for i in 1...10 {
+            particles.insert(Particle(uuid: NSUUID(), rssi: NSNumber(unsignedInt: arc4random_uniform(200)) ))
+        }
+        return ParticleSet(timestamp: NSDate(), nucleus: UIDevice.currentDevice().identifierForVendor, particles: particles)
+    }
+    
+    func createParticlesceneNode (particleSet: ParticleSet, zplane: Float, hue: CGFloat) -> SCNNode {
 //      create center Node
         let spereGeometry = SCNSphere(radius: 0.2)
         spereGeometry.firstMaterial!.diffuse.contents = UIColor.blackColor()

    func sceneSetup() {
        // 1
        let scene = SCNScene()
        var particles = Set<Particle>()
        
        for i in 1...10 {
        particles.insert(Particle(uuid: NSUUID(), rssi: NSNumber(unsignedInt: arc4random_uniform(200)) ))
        }
        
        let particleSet = ParticleSet(timestamp: NSDate(), nucleus: UIDevice.currentDevice().identifierForVendor, particles: particles)
        
        scene.rootNode.addChildNode( createParticlesceneNode (particleSet))

        particleSceneView.autoenablesDefaultLighting = true
        particleSceneView.allowsCameraControl = true

        
        for var i = 0 ; i < particleArray.count ; ++i {
            let particle = particleArray[i]
            let node = createParticleNode( particle, rotationOffset: Double(i) * rotationOffset, zplane: zplane, hue: hue)
            childNodes.append(node)
        }
        
