02560 Web Graphics and Scientific Visualization

Week 6 - the visualization pipeline (project proposals)

The visualization pipeline is best understood by applying it to some specific example. The lecture provides one example, which is also an example of hsv to rgb colour mapping for false-colour visualization of scalar attributes (see DV: Section 3.6). This example also makes more extensive use of the OpenGL ES Shading Language (GLSL ES) which is part of WebGL (see GL: Chapter 6 and Appendix B). To try a similar example, pick two images and load them as textures. One of them should preferably be a degraded version of the other. Make a WebGL program which can switch between the two images and their difference (by pressing space on the keyboard, for example). Use hsv to rgb colour mapping to generate a nice false-colour image when visualizing the difference between the two images. Describe the visualization pipeline of this example.

The time where a project should be chosen is drawing nearer. To help you choose your project, I provide a couple of project proposals in the following. A useful exercise is to write down what the visualization pipeline could be for these projects.

Choosing a project is all about choosing the data and the insight that we would like to obtain from the visualization. In essence, the project should come from curiosity: a question that we would like to answer.

Project initiator 1: What would it look like if we modify the surface of "this object"? [replace "this object" by some real object; a coffee mug, for example]
How to do it:

• Go to the ImageLab (we can arrange when) and scan "this object" using the structured light scanner.
• Reconstruct the object surface and its colours (using the MeshLab tool, for example).
• Make a WebGL tool for visualizing the object and for interactively modifying the object surface.
• Discuss 3D visualizations that could be relevant for this object if we ran a simulation (such as heating it; suppose we fill the mug with hot coffee and visualize the distribution of heat over time, this could answer how quickly the coffee gets cold and whether the user will burn her fingers).

Project initiator 2: What is inside a head and what can we learn from it?
How to do it:

• Obtain head scan data from the textbook webpage.
• Based on the code sample from the textbook webpage, write a loader which loads the head scan data into WebGL.
• Provide an interactive tool for visualizing the skull surface using isosurface extraction.
• Provide an interactive tool for visualizing the soft brain tissue using a slicing plane and voxel ray casting (volume visualization).
• Discuss what relevant information a doctor could obtain from such an interactive tool.
• Provide visualization aids to facilitate a medical use case.

Reading Material