Profile

Cover photo
Johannes Schindelin
320 followers|31,006 views
AboutPostsPhotosVideos+1's

Stream

 
+Jan Nieuwenhuizen I always meant to ask you: is there comprehensive documentation how LilyPond achieves the layout? Even after having hacked on it for a while, the unholy mix between seven languages (C++, Scheme, Python, PostScript, TeX, Shell, XML, not to mention LilyPond's language itself, ohloh lists even more: http://www.ohloh.net/p/lilypond/analyses/latest/languages_summary) makes it pretty obscure to understand.

I would actually only be interested in the layout algorithm itself...
1
Add a comment...
 
I wonder how many Ubuntu freezes it will take me yet to finally realize that ext4 is good only for corrupting my beautiful Git repositories by truncating random files to 0 bytes.

ReiserFS never did that to me.
1
Thiago Macieira's profile photoJohannes Schindelin's profile photoSverre Rabbelier's profile photoMartin Langhoff's profile photo
9 comments
 
+Torsten Rohlfing Ubuntu froze after I removed a USB disk (waiting until the message box appeared that said that it was safe to do so) and after Ubuntu failed to unregister said USB disk (and would also fail to detect newly-plugged-in devices).

+Stefan Beller my kernel is the vanilla Ubuntu one, I did not compile a custom one on this machine. And while it has an encrypted directory in the home directory, the corrupted Git repositories live outside of that directory...
Add a comment...

Johannes Schindelin

Shared publicly  - 
 
We should use this in OpenSPIM ;-)
 
Chicken-Powered image stabilizer

As you can see in the gif below , chickens are remarkably good at keeping their head still while their body is moving. They are able to do this when someone else moves their body,  but also when they move themselves. This is why a chicken's head (or a pigeon's head) bobs back and forth during walking: The chicken keeps its head still with respect to the environment by moving it backwards to compensate for the forwards body movement. This continues until the head cannot move back any further, at which point it rapidly snaps forward, momentarily breaking the otherwise near perfect head stabilization .

When you think of it, head stabilization is a remarkable feat: The gravitational (or vestibular) sense is required to keep the head up-right, regardless of the body's orientation. And you also need to take into account the position of the body parts relative to each other, which is called proprioception.

So the obvious question is: Why has the chicken evolved this remarkable ability to keep its head stable? An ability that surely requires a sophisticated neural apparatus.
In fact, this phenomenon is not limited to chickens, or even to birds. Almost all animals exhibit these types of stabilizing reflexes. Some engage their entire head, just like chickens do. Other animals, including ourselves, stabilize only the eyes. This allows us, for example, to keep our eyes fixed on someone throughout a conversation, despite the fact that we regularly nod or shake our head.

But why? Why the need to stabilize the head, or at least the eyes?

The answer lies in the way that the eyes work. Light shines through the pupil onto the retina in the back of the eye. You can therefore think of the eyes as containing a retinal image, formed by the pattern of light falling onto the retina.
But the retinal image has the following drawback: It is anchored to the eye, and therefore it changes when the eye, or the body to which the eye is attached, moves. Therefore, if an animal would not engage in any kind of stabilizing behaviour, all movement would result in disturbances of the retinal image, or retinal image motion.

But this begs the question: What's so bad about retinal image motion?
The first has to do with the sluggishness of the light sensitive cells, or photoreceptors, which form the basic building blocks of our eyes. This sluggishness imposes a fundamental limitation on vision: We cannot see things that are presented extremely briefly or that move very fast. If something flashes by too quickly, photoreceptors are simply not stimulated for a sufficient period of time. We may be able to catch a glimpse of something, but it will be blurry. And if we would not stabilize our eyes (or our entire head), our own movements would cause the world to sweep across the retina very rapidly. So rapidly, in fact, that it would cause blur. In other words, to prevent blurry vision, you should keep the eyes still.

The second reason has to do with the way that we process visual information once it has reached the brain. Or, more specifically, with how we detect motion. If our eyes don't move, motion detection is easy: All movement on the retina corresponds to movement 'out there' in the world. But if our eyes are moving, things become considerably more difficult. Because in that case the entire retinal image is always moving. Considerable computation will therefore be required to distinguish retinal motion that is artefactual, in the sense that it results from our own movement, from retinal motion that is real, in the sense that it corresponds to movement 'out there'.

So, in sum, the head stabilizing behaviour that you saw in the gif  serves an important purpose: It prevents unnecessary retinal image motion, and consequently avoids blurry vision and impaired motion detection.

References : Land, M.F., & Nilsson, D.E. (2002). Animal Eyes. Oxford, United Kingdom: Oxford University Press.
Sebastiaan Mathôt for  Laboratoire de Psychologie Cognitive at Aix-Marseille université.
http://www.cogsci.nl/blog/bird-brains-and-fish-eyes/177-stabilizing-vision-do-the-chicken-head
3
Add a comment...
1
1
Saúl Ares's profile photo
Add a comment...
Have him in circles
320 people
Lee Kamentsky's profile photo
Luis Ibanez's profile photo
Natalie Becker's profile photo
Carlos Neves's profile photo
Sebastian Rhode's profile photo
3
Thiago Macieira's profile photoJon Loeliger's profile photoJohannes Schindelin's profile photoMarian Johannes Endres's profile photo
4 comments
 
+Jon Loeliger given the interaction with the Git community I had during the past year (the loudest contributor "wins"), I actually can understand FB's decision to go with Mercurial.

Also, Mercurial's quite strict "Python only, C for hot paths only" policy makes it much, much easier to do what they did.
Add a comment...

Johannes Schindelin

Shared publicly  - 
 
 
This maybe perhaps the smallest oldest surviving ecosystem in the world. A garden in a bottle, planted by David Latimer in 1960 was last watered in the year 1972 before it was tightly sealed. David Latimer, 80, from Cranleigh in Surrey wanted to experiment how long the ecosystem will survive and to everybody’s amazement the little world is still thriving entirely on recycled air, nutrients and water.
 The only external thing fed to this bottled-garden was light without which there would be no energy for plants inside to create their own food and continue to grow. Other than that this is an entirely self-sufficient ecosystem, with the plant and bacteria in the soil working together.
18
8
Nicolette M's profile photoChristiane Mathy's profile photo
Add a comment...

Johannes Schindelin

Shared publicly  - 
 
Tricky question: in a plain Java application (no J2EE, no database, just a Swing interface for image processing), how is it possible to get instances of a class without running any of its initializers?
1
Carlos Rica's profile photoStephan Janosch's profile photoJohannes Schindelin's profile photogustav meedt's profile photo
6 comments
 
In stackoverflow I found a reference to the library http://objenesis.org/ but I don't know how they do it...
Add a comment...
 
I will never ever understand the inner workings for Google Chrome's address completion. Without fail, it finds exactly those parts of my browsing history that I absolutely do not want to visit right now, carefully leaving out the item that I actually want.

Only to "suggest" the correct URL when I typed the last character of it. Thanks, Chrome. You're such a big help.
1
Add a comment...

Johannes Schindelin

Shared publicly  - 
 
This stinks. If any of these characters approach you to do business with them (they'll most likely brag with winning the Hult Prize), you might want to reconsider doing business with them -- unless you are even worse. http://www.huffingtonpost.ca/2013/09/26/hult-prize-mcgill-jakub-dzamba_n_3995848.html
1
Torsten Rohlfing's profile photo
 
Why does this story remind me of Facebook... :-) 
Add a comment...
People
Have him in circles
320 people
Lee Kamentsky's profile photo
Luis Ibanez's profile photo
Natalie Becker's profile photo
Carlos Neves's profile photo
Sebastian Rhode's profile photo
Basic Information
Gender
Male
Work
Occupation
Image Processing, Git, Music
Links
Johannes Schindelin's +1's are the things they like, agree with, or want to recommend.
Fiji Is Just ImageJ
fiji.sc

Fiji is an image processing package. It can be described as a distribution of ImageJ together with Java, Java 3D and a lot of plugins organi

start | Image Processing and Analysis @EMBL
cmci.embl.de

Tweet. Image Processing and Analysis @EMBL. Trace: » start. | Login. » Index. Top Mission CMCI Seminar Courses Documents Downloads GitHub Li

PasswordMaker
chrome.google.com

Generates a unique password for every site from a single master password.

When will Google Drive come to Linux? - Google Product Forums
productforums.google.com

When will Google Drive come to Linux? arnieswap, 7/12/12 1:16 AM, It's been 4-5 months now and still there is no Google Drive client for Lin

Congress Considers Paywalling Science You Already Paid For
www.wired.com

Should you be able to read research you've helped to fund? A few years ago, Congress decided this was a good idea, and approved an access po

sverre
sverre.rabbelier.com

email: srabbelier@gmail.com (also gchat). irc: srabbelier on irc.freenode.net. twitter: http://twitter.com/srabbelier. linkedin: http://nl.l

Webmaster Tools
www.google.com

Improve your site's visibility in Google search results. It's free. Google Webmaster Tools provides you with detailed reports about

Like vs Plus
likevsplus.com

Let the battle begin! facebook like vs google plus one.