[NetBehaviour] Disaggregate Flocking?

Paul Hertz ignotus at gmail.com
Sat May 6 16:46:02 CEST 2023

For sure the behaviors of actual birds are far more complex than those of
boids. Similarly, L-systems model the growth of plant forms, but they truly
do not capture the way growth happens in plants.

Nevertheless, the simple models give rise to complexity, and their dynamics
might model something like a catastrophe inflection point. Some of the
sudden shifts you mention seem to me like a parameter of flocking behavior
suddenly changing value. I.e., coherence is suddenly greatly reduced,
large-scale flocking is absent, there's some local alignment, and above all
birds try to keep their distance ... as though failure to keep distance
precipitated the sudden drop in coherence? But that would be an image
within a simulation, not really an explanation of the dynamics of
food/mating/crowding, etc.

// Paul

On Sat, May 6, 2023 at 2:54 PM Alan Sondheim via NetBehaviour <
netbehaviour at lists.netbehaviour.org> wrote:

> Hi Paul!
> These are absolutely beautiful! I've been familiar with boyds for a long
> time and refreshed my memory before I did the piece. I don't have the
> skills to implement the work, but what I was interested in was probably
> closer to catastrophe theory (or what's left of catastrophe theory?). The
> aggregates were rougher; the cormorants played a role, and what was
> interesting was the sudden ragged shifts - all the gulls in one section
> between bridges took off, then a few seconds later, the next section etc.
> Or part of a section. But the pattern always appeared chaotic, not like
> wheeling pigeons or starlings for example. I was interested in what the
> birds were doing - they often dropped out and the patterning was often
> indiscernible, as were the flock boundaries - to the extent that it was
> unclear if there was flocking at all, just birds in the air over an area.
> So I wonder whether they're not reacting to a different form of coordinate
> system. The cormorants by the way do flock in a traditional pattern, but
> the gulls seemed more like Mandlebrot's percolations...
> The menhaden migration - literally billions of small fish, many of which
> die for lack of oxygen and coat the shoreline - was larger than usual
> because of the dredging. So the birds were coming in "from all over,"
> enough to make newspaper articles. And the gulls were "forced" into
> aggregates because the river system is narrow. There was enormous
> squabbling over water territory (i.e. the water surface occupied by a
> gull). It was strange as gulls and other birds also tried to flee at times;
> this was going on for at least a half mile out into the bay. I'm not sure
> the boyds model applies here since the crowding and jostling was largely
> incoherent, the closer the gulls got to the surface. I think a second
> interruption was mating rituals, since that seemed to be going on as well.
> The birds were on edge, I think, not used to this kind of crowding - a
> short interval in the video shows a serious fight between two starlings, in
> which one was almost killed (and was wounded); that's the first time we've
> seen that here before. A lot of the time we couldn't figure out what was
> going on. -
> I remember the game of Life of course, and "animals" in turbulence (static
> formations in moving water, but the term might be outmoded now).
> Your images and videos are amazing!
> Best, Alan, and thank you!
> On Sat, May 6, 2023 at 5:43 AM Paul Hertz via NetBehaviour <
> netbehaviour at lists.netbehaviour.org> wrote:
>> I think some of my flocking images might interest you, as might the code
>> behind them. I implemented Craig Reynolds' Boids Algorithm building on code
>> by Daniel Shiffman. I wanted to use the simulated flocks for drawing, not
>> unlike your multiple image bird paths.
>> Flocking and steering algorithms commonly use 3 or more parameters.
>> Separation, alignment, and cohesion are the principal ones, to which
>> field-of-view and other variables may be added. Separation refers to the
>> minimum distance between boids, alignment is the tendency to face the same
>> direction, cohesion is the distance over which flock cohere, and
>> field-of-view is the forward-facing angle within which boids "see" other
>> boids. Field-of-view can give rise to V-formations, so it's an interesting
>> addition. I didn't use it in my implementation.
>> Tweaking the variables (and their variability) can give you vastly
>> different behaviors, Boids with low cohesion distance and large alignment
>> distance have trouble flocking, for instance. They make very tangled paths
>> and never form a cloud of boids moving in the same direction. Much of the
>> variation you're suggesting could happen within a simulation, just by
>> varying the parameters.
>> Here's a selection from the first series I created:
>> https://flic.kr/s/aHsjzxxd6B. "Land Lines" is an homage to Colette and
>> Jeff Bangert, pioneers of algorithmic art.
>> A later series, https://flic.kr/s/aHskAU7qF2, used video tracking to
>> move the boids. The code allows you to wave your hands to move the boids,
>> or you can point the camera at traffic, to capture the flow, or whatever. I
>> installed it in a gallery pointing at foot traffic in the Chicago loop back
>> in 2016. Here's an example: https://vimeo.com/42786680.
>> The code for the version with video tracking still works on my new
>> MacBook, so it might be worth a try:
>> https://github.com/Ignotus-mago/Flocking. If you want to try it out, I
>> can help you with the installation.
>> // Paul
>> The first series
>> On Fri, May 5, 2023 at 5:14 PM Alan Sondheim via NetBehaviour <
>> netbehaviour at lists.netbehaviour.org> wrote:
>>> (might be useful re: Finsbury Park?)
>>> Disaggregate Flocking?
>>> https://youtu.be/R-J_KZI3dvY video
>>> Rather than swarming or flocking behavior, I'd like to call what
>>> I see in these images aggregate behavior or disaggregate
>>> behavior - what I mean is that the behavior is largely random
>>> that the gatherings are very crude and so very loosely bound
>>> that they fall apart constantly; they are "somewhat" incoherent.
>>> I wonder if instead of an overall flocking behavior algorithm
>>> algorithm one might consider or one might think about the
>>> possibilities of local geodesics that each bird follows that
>>> would have some relationship to avoidance behavior and to
>>> coagulation behavior but at the same time would not call this
>>> one way another into an overall shape such as you get with a
>>> murmuration or migration flocks . These things are much more
>>> loosely bound if they're bound at all with the goals in the
>>> images when you look at the time lapse material. When you look
>>> at the time lapse material you can see that they're much more
>>> individually moving then usually would be found In flocking
>>> behavior. If anything they're much more loosely bound by the
>>> external circumstances of the edges of the water body or bodies
>>> . But the movement seems to be slightly circular and that might
>>> be the result of flight patterns that are necessary to catch the
>>> air and move properly in relationship to the other birds to the
>>> neighbors but it might also be almost random and simply based on
>>> avoidive behavior and looking for geodesics not quite stop that.
>>> [that is, aggregative behavior within circumstances dictated by
>>> neighborhood features such as trees, pools, rivers.] Not looking
>>> for geodesics but as if they were following highly localized
>>> coordinates of some sort. I'm dictating this, which is another
>>> sort of flock behavior in the sense that the words are being put
>>> together with some kind of semantic continuity that the machine
>>> is interpreting. But at the same time there are withdrawals and
>>> things are much looser then that. In this sense the text itself
>>> is a kind of aggregate that veers off in one way or another.
>>> What was most amazing was when all of the all of the gulls took
>>> off simultaneously or roughly simultaneously not in a wave not
>>> even in a loose flock but from the bridge to the place where I
>>> was making the recording. More than that, there's a series of
>>> bridges and a farther bridge which is difficult to see in the
>>> video they also took off at the same time there must have been
>>> at least 1000 birds in the river between the two bridges and to
>>> further bridges that were even beyond those two. I'm fascinated
>>> by this and have spent a considerable amount of time trying to
>>> figure out what's going on. Ironically it's a lot easier, easier
>>> to figure out with the murmuration or sandhill cranes for
>>> example or migration in V shape patterns in general . But this
>>> seems different seems a different kind of behavior and the
>>> disorderliness may in fact be incredibly deep which would be
>>> really fascinating . Patsy disorderly oneness might in fact be
>>> incredibly deep . That is disorderliness might in fact be
>>> incredibly deep. It's the same with this as it is with the
>>> flight of these birds errors appearing everywhere in the text
>>> the text bearing off and then coming back just as the birds will
>>> land somewhat in the same places that they took off from
>>> somewhat in the same area at least but individually it becomes a
>>> real headache to try to I sect what's actually going on period
>>> to try to sense what's actually going on.
>>> ____
>>> _______________________________________________
>>> NetBehaviour mailing list
>>> NetBehaviour at lists.netbehaviour.org
>>> https://lists.netbehaviour.org/mailman/listinfo/netbehaviour
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