CS137 - HW1 Questions
Andrew Bragdon

1.	Tropical Cyclone (Hurricane) Visualization
2.	As part of this visualization I hope to evoke the awesome power and scale of the tropical cyclone.  Hurricanes have played a very important role in history - a role few would view as positive.  With the devastation of Hurricane Katrina, and other more recent events still fresh in the minds of many, I hope to show the face of the monster that is the tropical cyclone.  I hope to contrast the impressive destructive power and scale of the hurricane with an increased understanding of the hurricane by revealing its ordered structure.  In addition I hope to instill an impression of ordered structure in users as they view the hurricane visualization.
3.	In the case of a hurricane, which is composed primarily of moving air and water vapor, form can be given to the complex processes within a hurricane by visualizing these two largely invisible components through the use of false-color representations.  I chose to represent the speed and force of moving air by the density of small colored streaks, and I chose to represent the temperature of the air by the color of each streak.  I chose to represent the density of water vapor with the density of small dots, and the temperature of the water vapor by color.  Because the streaks are long and narrow, and the dots are circular it is straightforward for users to see these representations as distinct.  I felt that the streaks evoked the moving currents of air and the dots more closely resembled droplets of water, thus giving a visual cue as to the nature of each.
4.	In the case of the hurricane, the high-level, distinctive spiral form is a result of the Coriolis Effect.  As the Earth rotates on its axis, the path of airflows is bent into a spiral pattern as the air flows toward the low-pressure zone at the center of the hurricane.

The calm and windless eye of the hurricane, an essential aspect of its form, is the result of a wall of fast-moving air around the eye which prevents incoming air from reaching the eye.  This creates a virtuous cycle in which new incoming air lends speed and power to the eye wall, further sequestering the eye from incoming air.
5.	Because the air currents and water vapor which comprise a hurricane are constantly in motion, I felt that it was important that the visualization clearly evoke this constant flow.  In contrast, I wanted to show the relatively stationary environment in which a hurricane is created - warm ocean water - as a clear contrast.  Thus, I used a photographic approach for visualizing the ocean water as a contrast to the flow of the air currents and water vapor.  As described above, air currents were represented as streak-like elements, which evoke the concept of flow through their elongated paths and relative density.  In addition, I tried to create a sense of volume for the air currents by adding in additional detail elements to create density in three dimensions. 
6.	The form of the tropical cyclone (atmospheric) is very similar in character to that of a spiral galaxy (energy), and to flows of milk and water in a sink (liquid).  Although galaxies are primarily a collection of stars which emit light, they originally formed as large clouds of gas and dust - analogous to the atmosphere of the Earth.  Flows of milk and water in a sink are, in some sense, similar to the flows of air and water vapor in a hurricane as both are fluid-like occurrences.  Between each of these three there is a tremendous differrence in scale, and yet the forms are similar.
7.	I wanted to create the sensation of drawing the viewer in.  One way I did this was by designing the visualization to offer additional detail at differrent scale levels.  At the highest level users can see the size and scale of the hurricane relative to the ocean and the thickness of the atmosphere (through the stratosphere layer).  Then, the flows of air in the hurricane itself provide a second level of scale.  Lastly, a cutaway piece of the hurricane reveals the motion of water vapor through the hurricane into the Eye Wall at the smallest scale level.  Each of these scale levels is clearly visible from the other scale levels but is differrent enough in scale as to suggest that additional detail can be gleaned by "zooming" in or out as needed. 
8.	Yes and no.  Yes in that the resolution of the cave and the size of the screens is sufficient to view the visualization as intended.  No in that hurricanes are probably too large (hundreds of miles) to comfortably navigate on a 1:1 scale ratio without additional tools in cave painting to facilitate warping to differrent locations. 
9.	I chose to depict the entirety of my visualization with a complex combination of 2D transparent images.  I wanted to be able to create highly complex, but also highly precise images.  I felt that freehanding them with the cave painting brushes would be very difficult and time consuming and that it would also be hard to control color precisely to visualize temperature.  Therefore I felt that it would be a better approach to use transparent images layered together to create a volumetric 3D representation, as these images could be created digitally in Photoshop with computer precision and control.  I was then able to use the slide tool to create layer small and large transparent images together to create the final visualization.
10.	See answer to question 9 above.
11.	No. 
12.	Yes- the tracker was down and also there were some issues with my configuration files because the person who set them up accidentally put "abc" instead of "acb" in several key places.
13.	Yes, although I did not end up using these features in my final design (see answer to question 9 above). 
14.	Has a spherical cave been done?  I have seen a recent Microsoft Research project to create a spherical multi-touch, rear-projection surface (the inversion of what a spherical cave would look like). 
15.	I think that the best way to improve this assignment would be to have an assignment 0 which came before that would help to work all the bugs out of the cave accounts.  Assignment 0 would be just to make a "hello world" visualization in the cave, that included at least one image-based slide.  Every student would be required to turn it in, but it would not be graded.  This would really help to avoid many of the getting started-related cave problems I and probably others ran into.

As a side note, I think that Cavepainting should support 8-bit masks rather than 1-bit masks.  Photoshop and other image processing applications are really designed to create rich masks and generating 1-bit masks from these richer masks does not work well and requires significant time.