Chapter 7: SCIRun User Interaction

Chapter Sections

Chapter Overview

Chapter 6 demonstrated how to combine simulation and visualization components to form a complete dataflow network. While the visualization components were dynamic (i.e., changing the isovalue or streamline seed positions changed the visualization), the models were static. Chapter 7 illustrates adding a feedback module that allows the user to change the position of the dipole model, and interactively visualize the results.

ShowDipoles

Insert a module into the net from Chapter 6 as shown in Figure 7.1. The ShowDipoles module is located under the BioPSE->Visualization menu. ShowDipoles takes in a PointCloud of vectors (the SCIRun representation for a group of dipoles), allowing the user to visualize and interact with those dipoles. Insert a ShowDipoles module into the net.


Figure 7.1: ShowDipoles Added to the Chapter 6 Network

The ShowDipoles module has two outputs; a Field and a geometry object. The geometry object attaches to the Viewer module, graphically depicting the dipoles as arrow widgets. At each release of the mouse, an updated version of the dipole positions passes through the Field output port, and into the ApplyFEMCurrentSource module.

The ShowDipoles UI (Figure 7.2) has several configuration options for controlling how the dipoles are graphically displayed. In the ShowDipoles UI:

  1. Select the Normalize Largest radio button.

  2. Set the Widget Size to 10.

  3. Select Show Last As Vector.

  4. Unselect Show Lines.

These options result in a set of dipoles with uniformly scaled lengths. The longest vector is now a length 10.


Figure 7.2: ShowDipoles UI

Connecting the ShowDipoles modul results in a complete forward finite element network. Figure 7.3 contains the resulting visualization that appears in the ViewWindow. This is the same net provided in the SCIRun software installation as:Packages/BioPSE/nets/forward-fem.net


Figure 7.3: Forward Finite Element Net ViewWindow

The white arrows in Figure7.3 indicate that the widget can be moved around to interactively rotate and shift the rake widget (the arrows do not appear in the ViewWindow when the user builds this network).

Summary

Experiment with the completed network. Explore how different dipole source positions and directions affect the voltage and electric Field distributions through the volume.

Compare different linear solution methods with the SolveMatrix module, or compare isosurface extraction times using MC (Marching Cubes) versus the NOISE (Near-Optimal IsoSurface Extraction) algorithm. SCIRun is a flexible environment designed for interactive exploration of what-if scenarios.

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