3D Visualization of Multiple Variables

CS137 Assignment #3

1. Dates

2. Goals

1. Learn about the complexities of translating your 2D gradients on to 3D.
2. Identify and understand the perceptual and technical issues involved in 3D gradient visualization as compared to 2D gradients.
3. Consider issues with transparency, visibility, color, and interaction with bat wing surface.
4. Learn how new scientific and perceptual variables become important when a problem is in 3D.

3. Readings

• Check the Calendar page of the website.
• There are 2 books at the Cave that you may consult. As always, these books are not to leave the Cave room:
  • The Miracle of Flight, by Dalton
  • Fundamentals of Aerodynamics, by Anderson
• Check out the websites from the links page. Some of them relate to flight theory and have tons of examples and pictures.
• Check out the bibliographies for the VRL bat project, artery project and flow viz reading list. These are all technical papers related to flow visualization, but they represent the state of the art and might inspire some designs.

4. Assignment

4.1 Part A: 3D Wing and Flow Visualization

Design a strategy for a single frame visualization of the interaction between a section of wing surface and surrounding air flow featuring pressure of flow (underside/topside), velocity and vorticity. With the help of the readings and the class lectures do the following:

• Pose a hypothesis of how the flow of air would move around the bat wing and make your visualization method work to validate that hypothesis. For example, if your hypothesis is that Bernoulli’s Theorem indicates that lower pressure above the wing, caused by camber would generate lift, include the important factors and adjustments to the visual emphasis of your model to clearly show this aspect of the situation to the user.
• Utilizing the SAME elements and visualization method, show an instance of flow around the wing where the initial hypothesis is NOT validated. For example, your icons indicating pressure might suggest that the air flow above the wing is separating due to surface irregularity, undercutting the forces tied to Bernoulli’s theorem.

This process mimics, in only two iterations, the process for designing visualizations and analyzing real scientific data. The hand-in for this first part of the assignment has to include these 3 steps:

1. verbal hypothesis
2. visualization supporting the hypothesis
3. visualization contradicting the hypothesis

You should be ready to explain each one of them in class.

Your designs or “sketches” should be executed in a medium that allows you to address the 3-D character of the situation under study, with an eye toward eventual VR implementation in the Cave. You can actually sketch in the Cave, saving and printing enough snapshots to clearly show what’s happening in your model. Or you can construct a 3-D model using physical materials such as acetate, foil, cardboard, wire, string, paint, clay etc. You might also use a 3-D digital program such as Maya or cinema 4-D, or sketch in a 2-D mode Photoshop, or with paint/pencil etc. If you are using 2-D means, you will have to suggest qualities of three-dimensionality thorough illusionism, perspective etc. and include as many views as is necessary for the class to understand you idea.

The crit will be in the classroom.

Try to bring in your ideas from the 'Force and Form' assignment and explicitly target the interaction between air and wing. The 2D flow assignment should help you with what types of variables are part of a flow representation, how they are used and why they are important. If you have any other intuitive elements of the flow that you'd like to display, please do so, but be ready to explain why you think they are important and how they relate to the other variables. It's ok to come up with your own variable that captures some feature of the flow you think important. Chances are there's a scientific name for it already and Sharon might be able to explain what it is.

Also, think about your legend for the 3D environment. Where will it be placed? Will it be interactive or animated?

4.2 Part B: VR Implementation

Put your design in CavePainting. You should use the 'frame-by-frame' feature of CavePainting to show your flow visualization move. We will make available to you a section of the bat wing in various positions along the wing beat. You can use these as reference for the form or you can make your own representation of the bat wing. You should include your legend in the 3D environment.

5. Questions (answer briefly)

Questions are due, emailed to the TA, by 11am on the date listed above. Most of these are very short questions intended to help guide you through the assignment. They should not take long to answer. Most of the time, a very brief, one sentence or less, answer is sufficient.

1. How did your knowledge of 2D flow translate into 3D?
2. What challenges did that transition present to you?
3. Did you think going from 2D to 3D would be easier or harder? why?
4. What are the factors behind your choice of visual characteristics to represent the flow and its associated variables?