Andrew Bearnot

CS137: Assignment #4: Questions

1. What was the most challenging part of having to show all the elements of the wing structure at once?

I chose not to concern myself too much with the wing structure itself. Rather, I focused on how the skeleton moves between “frames”: kinematics. What seems to be most challenging about showing the connection between discrete positions in the wing beat cycle is understanding the three dimensionality of the motion. This problem includes visual confusion like depth perception and overlap, but also the difficulty of connecting one position in flight to the next just based on your memory of the previous frame. I directed by visualization at manifesting these spatial connections, so that you can look at any one position and inspect “where it has been.”

I experimented a lot with the type of lines I used to connect positions, which Fritz has termed “streamers.” I chose to make them graduated in color, with evenly spaced dash marks along their length. These marks are closer together on “slower” segments (shorter length over the time period), and farther apart between positions where the wing is moving “faster.” I began by including the streamer from the last frame as well (thus implying three positions in a single frame), but decided it was too confusing. I would also like to try including the streamer from the next frame, so that you can see where the position of the wing was and where it is going. Unfortunately, I could not figure out a way to implement this on a separate layer without redrawing everything.

2. What visual tradeoffs did you have to make to keep the composition "stable" throughout the wingbeat while highlighting the important part?

In addition to the one frame streamers at every point, I built another layer which track the motion at four crucial points (both wing tips, wrist and elbow). At these points the motion is tracked cumulatively, so that by the end of the wing-beat, a full cycle has been constructed. I drew these lines out of a much thicker version of the “streamers.” This allows for a part of the composition to appear “stable” throughout the animation, and allows you to consider the overall, abstract spatial architecture of the stroke rather than focusing on the shape of the wing. As Nick mentioned, this might be particularly helpful in comparison with other species. I also experimented with drawing the whole loop in each frame so that it would remain constant throughout, but found that it confused the forward and backward direction of motion (unless flipping rapidly through the positions).

3. What visual characteristics did you use to represent each part of the wing and why?

I simply connected the markers representing the bat itself with white tubes. However, I used contrasting light sources from above and below to give the tube more depth (I believe it also has some texture on it which helps with depth perception). All positions are treated equivalently in terms of structure, but as mentioned in (2) I focused on the movement at four specific locations. These locations are at the extrema of the wing, and exhibit the largest displacements. Thus they seemed the most representative of the total wing motion, and also the least likely to overlap. If I were to re-build the visualization, I would probably put each one of these “loops” on a separate layer.