Category Listing
Monthly Archive
Baseball Reference
Red Sox Links

Recent Posts
Recent Comments
Essential Empy

Home » Dave’s DiegesesApril 2005 » Dave’s Diegesis: Beyond the Fields We Know

Dave’s Diegesis: Beyond the Fields We Know

Out beyond ideas of wrongdoing and rightdoing, there is a field. I will meet you there.
Jalal ad-Din Rumi

You might think of me as simply an outstanding first baseman, especially after that play I made earlier this week, but I also pride myself in my outfield prowess. Whenever I’m prowling the edges of the field robbing hitters of extra base hits, the other guys ask me what the heck I’m doing out there. So I tell them I’m using a combination of the linear optical trajectory (LOT) and optical acceleration cancellation (OAC) models of tracking moving objects.

Some of my teammates think I’m crazy for using both LOT and OAC, because I guess they are proponents of a simplified adoption of either one or the other. I then decided to attempt to prove that my tactic was correct. I had offered to take part in this April 2002 study, but after I had sent a dozen or so e-mails to Dennis Shaffer and Michael McBeath, the authors, with some of my suggestions, they regretfully informed me that they had all the participants they needed. It was a great effort, however, only to be refuted by a competing faction with this comment in December of 2002.

OacFielders using the OAC model supposedly have a two-step approach. They first align themselves horizontally with the path of the ball, then they run towards to ball at a speed that makes it appear as if it were rising at a constant rate. For this approach to be successful, fielders need to adjust to the correct speed to cancel the ball’s acceleration. Run too slowly and the ball will appear to slow down and land in front of the fielder; too quickly, and the ball seemingly speeds up and land behind the fielder. The essential assumption behind this method is that people are adept at discerning acceleration, which is actually not the case. In practice, the most difficult ball to field is one hit directly at a fielder, while the OAC theory presumes that it would require more effort to run laterally to the flight of the ball. I’ll be the first to tell you, and I’m not alone among outfielders, that it is actually easier to track down a ball from the side.

LotThis brings us to the LOT framework. LOT assumes that a fielder uses the differential between straight and curved trajectories rather than changes in speed. The LOT theory is based on evidence that people are better at determining minute changes in optical curvature. When I’m out in the field, the ball looks like it moves in a straight line and at a constant speed relative to the background scenery. To counteract this, I would run on a curved path to accommodate the curvature of the ball’s trajectory.

There are limitations to using only one of the methods at a time, so, like the best outfielders, I use an amalgam of both strategies. Especially on windy days or balls hit with a lot of spin, where the trajectory of the ball is less predictable, both modes should be employed.

Every Friday, Dave McCarty will join us to discuss a topic of interest to him and probably no one else but the author of this site, and this week perhaps Ultimate aficionados like NU five oh who likely use a synthesis of LOT and OAC when playing.


I'll be the first to admit that I am blushing like a fanboy as I write this comment. Oh my gosh! My name is on the internet, written by a person that's not me! I've finally made it! (Don't mistake the excessive use of exclamation points, I am genuinely flattered).

Ultimate, a fantastic sport if you've never played (I'd say "or watched", but virtually no one spectates at Ultimate games), has a lot more intricacies in tracking discs as opposed to an outfielder tracking a ball, primarily due to the fact that you see such a variety of tosses over the course of a game. Short fast throws I would imagine look more like a sharp liner at an infielder, while upside down throws like hammers, thumbers and scoobers can sometimes flutter and stall like a Tim Wakefield knuckleball. However, your pulls (kickoffs, for you non-ultimaters) and hucks can be read similar to a long fly off of a bat. However, due to player positioning, you tend to alternate between one method or the other.

When being pulled to, OAC is the disc reading method of choice. Field's are about as wide as the area an outfielder would need to cover (40 yards wide is regulation, but I've played anywhere between 30 or 45 yards). However, the nature of a disc's flight allows it to maintain a considerably longer hangtime than even flyouts in danger of clipping a catwalk at the Trop. Traditional pulls look to maximize hangtime first, and distance second, so while you would size up the disc much like you would a flyball using the OAC method, you do so at a much slower rate than Dave would be used to.

Hucks on the other hand behave much differently than pulls (or at least, effective ones do). A huck looks to maximize distance and speed, putting the disc in front of the reciever to a place he can get to it whilst his defender can not. Due to this, they tend to travel much like a line drive to a gap would, rarely much over 15 feet off the ground and at a fast speed. The LOT method is used almost exclusively for hucks, because quite often it is the reciever running away from the disc's point of origin to catch up to it downfield, like a long drive to the wall over Dave's head. The OAC method is relatively useless here, because if you are infront of a huck letting it come to you, chances are your defender is too, and if the disc is hanging in the air too long, it makes for an easy defensive play.

One other comparison between the flight of a baseball and the flight of a frisbee actually occurs in the batter's box. For any flight of the disc, the disc's pitch must be called into account. Even only a few degrees of list to either side can create a bank of 10 or so yards in either direction over a relatively short distance. This can be done intentionally to make an inside-out or outside-in banking toss, or it could just be a poor throw which can bank up to, and sometimes even past a 90 degree turn. Often times, this reading of the disc's flight must occur in the first fractions of a second as the disc leaves the throwers hand, especially if you are playing defense. I would imagine that this is similar to how a batter will read not only the rotation of a ball as it leaves the pitcher's hand as well as how the pitcher grips the ball on his release (as Ultimate too has many different grips it employs) in order to determine where the pitch will end up.

So, in summary, while the opportunity to employ a synthesis of OAC and LOT schemes for reading the flight of an object, be it a baseball or a disc, are rare, each method is used extensively throughout Ultimate play.

And thus concludes my dreadfully long comment (I might have a higher word count than Dave on this one)which almost certainly interests only me, and perhaps Dave if a road trip is particularly boring. I'll bet Bellhorn has a disc he can toss.

NU50, thank you for your insight into the nuances of Ultimate. I had suspected that the flight of a disc is much more variable than that of a baseball, but otherwise I think many of the visual processing tasks we both undergo in trying to intercept a flying object are analogous. In your sport, however, the introduction of a defender complicates matters. I did some further research into catching strategies, and found more questions than answers.

With both LOT and OAC, there are problems that do not account for all cases of object interception. As described by Ryosuke Mori and Fumio Miyazaki (1), holes in these processes are:

a. OAC and LOT both make assumptions that the fielder is either in the ball trajectory plane or not in said plane, respectively. This is not always the case.
b. It is unclear in LOT how the fielder decides to modify direction and path as he or she processes visual data.
c. Parameters for the success or failure of OAC and LOT are not defined.

Mori and Miyazaki propose a synthesis of the two approaches which they call "Gaining Angle of Gaze," or GAG. (Like, gag me with a spoon, totally.) Note that their background is advanced robotics and engineering, so their solution to describing human strategies is based on whether or not they can replicate our visual processing behavior with equivalent algorithms. They were able to successfully implement the GAG strategy in a robot by using only the angle of elevation of gaze as the input. They also created a visual feedback control scheme based on GAG that enables the robot to track and catch a ball flying in three-dimensional space by using only a monocular vision system.

My hesitation in accepting GAG is that it is a purely mathematical reduction of a human activity. As with any implementation of artificial intelligence, engineers cannot delineate or describe the multiple and possibly simultaneous methods people use to solve problems. Furthermore, in their point labeled "c" above clearly shows these authors' biases. Their work needs defined parameters because their raw materials (processing software and robots) have limitations. Of course, people have limitations as well, but perhaps can perform outside of assumed restrictions with a burst of adrenaline.

From the realm of neuropsychology, Richard S. Marken proposes a "Unified Fielder Theory" (Cute name, isn't it?) (2), where Marken extends Powers's "control system" theory, which states "a control system acts to bring a perception of some aspect of its environment to a predetermined or reference state while protecting it from the effects of disturbance. This process is called control and the perception that is brought to and maintained in the reference state is called a controlled variable."

In the case of fielding, Marken claims that a fielder’s actions actually occur in a closed loop. The path the fielder selects influences the fielder's perception and vice versa. While this dialectic is happening, the fielder processes this information against his or her reference state.

This theory has the opposite problem of the GAG hypothesis as it is almost entirely based on human perception. Until human brain response and processing is completely understood and quauntifiable, neuropsychological concepts largely ascribe grand theories of behavior to the brain, which is treated as a black box. Perhaps one day functional magnetic resonance imaging (fMRI) will be able to track the minute metabolic changes within our brains and these fluctuations can provide objective proof human coginition.

As I said, I think I've raised more questions than I've answered here, but this is because baseball touches on so many emergent scientific disciplines. Meanwhile, I take you up on a game of Ultimate. I'm sure my 6'5" frame will be an advantage.

1. R. Mori and F. Miyazaki: "GAG (Gaining Angle of Gaze) Strategy for Ball Tracking and Catching Task - Implementation of GAG to a Mobile Robot." Proc. of the 11th Int. Conf. on Advanced Robotics, Coimbra, Portugal, 2003.
2. R. S. Marken: "Fielder’s Choice: A Unified Theory of Catching Fly Balls." The RAND Corporation, Santa Monica, California, 2002.
3. W. T. Powers: "Behavior: The control of perception." Chicago, Illinois, Aldine-DeGruyter, 1973.

Did the MacDaddy pay for the domain, ostrichboy.com????I think somebody gave the thing to him,because after all, if you help win a world series in this town, you dont pay for shit after that...


I find the concept of a robot capable of shagging fly balls immensely intriguing. I spent the better part of an afternoon simply imagining the structural design of such a robot. Does it have a butterfly net to snare the ball mid-flight, or something more similar to an outfielder's glove? Does it have wheels, or is it one of the sophisticated "walking robots" I've seen developed? Were it my robot, I would most likely opt for a tracked design, as I imagine tight turning radius would be at a premium.

Your further research certainly begins to raise many more questions than answers. The one I find most perplexing is how much of this decision making is conscious, and how much is instinctual. While a more learned athlete can look at the potential benifits and weaknesses of a particular method of object tracking, what would make a more layman fielder more likely to use one over the other? If Manny is losing balls in the sun due to improper employment of OAC, could he learn to use LOT or GAG, or is that particular method of perception hard-wired into his brain? Then again, maybe that's a bad example, as the only way I can imagine Mr. Ramirez using those words together in a sentence is: "When I eat pOAChed eggs, I GAG a LOT".

As for that Ultimate game, you certainly would have the advantage as a deep threat as I'm giving you several inches and greater experience with object flight tracking, however I think I hold the advantage in the short game, even with your sinister left handedness. Throwing a disc is far different than a ball (unless you are BH Kim or maybe Mike Meyers), and I imagine that you'll have some trouble with the foreign concept of a "pivot foot". I'm sure you might appreciate the novel concept of self-regulated games, however, as only the national championships of Ultimate employ officials (**cough** Greg Gibson **cough**).

In my book "Ultimate Techniques and Tactics" (co-authored with Eric Zaslow), I also talk about tracking a disc's flight, specifically while chasing down hucks. I had read some of the literature (there was an NYT article titled "Flyball or Frisbee, Dog or Frisbee Do the Same Physics"). Anyway, from page 62, here's a pre-edited version of what I had to say (sorry about the formatting):

The optimal cutting path for a deep path is determined by a variety of factors. Generally, it is NOT a straight line between where you are and where you want to be. Rather, it is a gently-curving path that is straight downfield for the first 15 yards or so before arcing toward the disc. This path leaves open space for the thrower and affords you more room away from the stack, where poachers might be waiting. There are at least three reasons you might not get picked up if you’re farther away:
· The poachers will have to move a greater distance and thus can’t pop out quickly without leaving their own offenders wide open.
· They might mis-estimate where you’re heading if they just go to the spot along your original straight-line path.
· They might not even see you.
It is crucial in the first few steps that you go all-out, without looking back for the disc until you have achieved separation from your defender. Then, you may glance back to reassess the situation, but do not continue to run with your head turned, as this slows you down. Once you have broken free from your defender and the stack, you begin tracking the disc, adjusting your path to head to the likely point of reception. Keep it in front of you because it’s easier to adjust toward the disc to catch it than it is to move back away from the disc. (See “Boxing out and skying” in chapter 5.) Furthermore, the defender is usually behind you and isn’t just going to let you force him back.

Finally, the strategies of your offense and the opponent’s defense will have some effect on your cutting path. Most deep passes should have some crossfield component to them, so that if the pass is underthrown or overthrown, you can adjust your path to head it off sooner or later, as needed. This opportunity won’t exist if both the throw and the cut are straight down the field so that pass has to be nearly perfectly thrown to be caught. Below are three examples of deep cuts and the path the receiver takes. There is really no conceptual difference among them, but each cut will have a different start point and end point.

Thanks for the help, Jim. Is the book out yet? I noticed you said the passage was "pre-edited", so I'm not sure if that means it isn't published. Defintiely sounds like a good read, and I always enjoy things that might make me a better player, be they reading material, our tips from utility baseball players, or stories of anthropomorphic robots.

Especially if they involve robots.

The book has been out since April 2004, and is available through the publisher Human Kinetics or at Amazon.com (or a slew of other places). I used "pre-edited" to indicate "what I wrote before it went through final editing because I don't have an electronic version of the final copy and I wanted merely to cut and paste."

« Top « Home » Category ListingMonthly Archive


RSS Feed



  • Visitors to EE since November 2004
  • Boston Phoenix Best of ’06
    Phoenix Best
  • Blog contents, images, and design
    © 2004-2015 by Joanna J.M. Hicks.
    All Rights Reserved.
    Copyrights and trademarks for the books, films, articles, and other materials are held by their respective owners and their use is allowed under the fair use clause of the Copyright Law.