Week 9 Summaries
Alice
The Alice is a user friendly 3D graphics generator that aims for unskilled 3D graphics users. The authors begin with introducing the two main assumptions for prospective users: the users are assumed to have small mathematical or programming background for 3D graphics programming and the users are assumed to have no experience with programming.
The Alice consists of 3D objects in the scene and scripts that move the objects in the scene. The objects are organized as a form of tree with separating “first class object” and “a part of an object.” The scripting of Alice is made of straightforward python language with lots of overloading. The number of overloaded functions in Alice lets beginners to learn 3D graphics programming gradually. The authors implemented straightforward terminology for function names and dealing with coordinate systems. The authors represent coordinate system in terms of object oriented terminology to make dealing with coordinate system easier for users without mathematical understanding of how 3D graphics programming works. The authors also did survey on units for rotations as well and it turned out that turns per second is most intuitive unit for rotation for beginners.
With easily approachable Alice 3D graphics system, the authors did user study with 100 people with no programming experience to go through the Alice tutorial. As a result, the authors found out that users were more familiar with up/down object oriented directions than XYZ coordinate system. With AsSeenBy command, the users were able to deal with coordinate merging more intuitively. The 0 to 1 range numeric parameter were more familiar to people learning 3D graphics. Alice is a great system that lets 3D graphics work to be done in more generally.
Everquest2
The authors describe two main aspects of MMORPG that make the study of latency in MMORPG a reasonable study: the total number of players are huge and the size of world is huge. The authors describe how usual game service providers handle these two issues by showing example architecture of generally used game server. The authors adopt a 3-step experiment to see the effect of latency on certain game situations.
First, the authors categorize important game situations and build test situations for all of them. In Everquest 2, there is no “endgame” goal that make player win the game. Thus, the authors defined characteristics of good players such as item knowledge, character strength, and character understanding. Secondly, the authors built the Testbed system consisting with two PCs and a switch to control internet stream going on between two PCs. Finally, the authors define a few situations where latency can affect player’s performance.
The first situation is movement and combat. This is the task that both participants start at the same point and kill exact same monsters and reach the goal as fast as possible. The second situation is group combat. In this situation, two participants were designated as a healer and fighter combination and fight against a challenging monster as fast as possible. The third situation is divided into two different experiments. In one experiment, a participant stood still and other participants ran toward the standing participants. In this experiment, only one participant takes screenshots but in the second experiment, both players take screenshots.
Then, the authors analyze the experiment results. As the latency went up, the time taken to finish each situation went up for about 1 minute in average. Also, the character resource status after the battle went down as the latency went up. In high latency environments, the other client couldn’t predict the movement of the other player and it resulted in difference in translation between two screenshots taken by each player. Overall, the paper summarized the effect of latency in gaming environment and showed that the developers need to contemplate for latency control in order to keep application most productive through the user experience.
DART
DART is an AR toolkit built upon Macromedia Director for designers without professional programming experiences to build AR experience directly and effectively. The authors describe the reason why AR is a difficult medium to work with for designers. The problems are no simple programming environment for AR, programming for AR must be done in low level, and hardness of sensing and tracking technology.
The authors want to push AR as a popular medium by making it easy enough for designers without professional knowledge to work with. Motivated by Alice, Three Angry Men, and Four Angry Men, the authors build a toolkit upon Director to reduce a burden of learning a new tool for designers. With Lingo scripts that most interaction designers are familiar with, DART can rapidly produce the content with 3D characters from 2D storyboard created by designers. DART supports series of actors, framework, events, physics, and datastore that represent each part of DART behaviors.
In implementing DART upon Director, the authors encountered the problem that 3D content is not well integrated within Director. They use the Container Sprites to go around this problem with using Shockwave3D and each DART behavior attached to the sprites get AR-specific functionalities by using the Container Sprites.
DART enables fast creation of AR experience by a few characteristics. AR actors enable fast exploration of data. Using 3 types of actor, DART represent objects in the scene, interacting characters in the scene, and augmenting video in the scene. The capture and playback synchronized with tracking and sensory data reduce inconvenience generate by working with real and noisy data. Using cue and actions, DART provide AR-specific event-based programming between actors in the scene. Also, DART provides marker-based tracking and supervised tracking to meet the needs of designers addressing different characteristics of tracking data in different situations.
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