CashFlow, A Visualization Framework for 3D Flow - Studierstube ...

Software Design3.2. Using the Scene Graph3.2 Using the Scene GraphIn this section we want to take a closer look at the data flow inside CashFlow and howthe scene graph is used. As mentioned in the previous section 3.1 CashFlow uses avisualization pipeline (see figure 3.1 on page 38). The three basic components Data,Mapper and Render are used in a scene graph.A simple example is shown in figure 3.2. Artificial data is mapped to four differentgrids. On the bottom left a polar grid with a color map created from the artificial data.On the top left the same polar grid mapped on a height field generated from the artificialdata. On the bottom right a Cartesian grid with the same color map. And on the topright a Cartesian grid with a height field also generated from the same artificial data.The same artificial data is used to generate these four visualizations. Note, that the dataitself is not defined on one of those grids, which makes no visual representation moreappropriate than the other.Figure 3.2: CashFlow: Abstract data mapped onto Cartesian and polar grid. Data values are used tocreate color map and height field. Corresponding CashFlow scene graph shown in figure 3.10 on page 51.A simplified scene graph of the visualization in figure 3.2 is shown in figure 3.3 onpage 43. The scene graph is traversed from root node R. Node A and node C storeddata and are empty in the beginning. Node B is a loader loading data from storage tonode A. Node D is a mapper mapping the data from node A to a color map stored innode C. During the first traversal node B insert new data into the scene graph. Node Dalso create new data in the form of a color map. In the following traversals node B andnode D are inactive since the data is already loaded and has not changed.The recursion of the depth–first–search scene graph traversal including node A-Dis resolved and nodes E-H et cetera are traversed. After traversing node A up to node42