a weird example of Persistence of Vision

Ok, you’ve probably seen this already, but let’s try to understand why our vision system creates such a weird image distortion effect. Look at the .gif image below here. Focus on the white cross and keep your eyes on that during the animation. Why does your peripheral vision see? Why normal faces become weird distorted aliens? ūüėÄ


Here’s the trick:¬†our brain blends images together¬†if we scroll through them quickly enough. In cinema and animation, our eyes (and brain) start blending images if the frame rate is higher than 16 frames per second.


Instead of seeing flashing separated images, our mind is able to create a more or less continuous motion between each frame and the other. That’s why, for¬†both physical¬†film¬†and¬†digital cinema¬†systems,¬†modern theatrical films run at 24 frames per second (even 48 in the case of Maxivision). The typical example of this phenomenon is given by the¬†Zoetrope, that produces the illusion of motion from a rapid succession of static pictures.

The phenomenon that is responsible for this is the Phi phenomenon, defined by Wikipedia as “the optical illusion of perceiving continuous motion between separate objects viewed rapidly in succession“. Together with the Beta movement, these two perceptual illusions represent a¬†plausible theory to explain motion perception. In more general terms, we are talking about Persistence of vision.¬†Again with the cinema example, movies are rapid sequences of discrete images, but persistence of vision smoothes out movement, making transitions subtle and comprehensive.

other sources: one and two

2 news + Differential Gear

Hello people! ūüôā

arrow-right-upThe first news is that I’ve added a mailto button right here, under the LinkedIn button. Recently I’ve received some e-mails asking me to share other website’s contents… Well, I don’t think my blog has billions of readers, but apparently some of you appreciate my posts. I thought it could be useful to add a simple button to have a simpler way to discuss. Feel free to write me an e-mail if you want to!

The second news is that the Guestbook was kind of an epic fail. Actually its quite useless, so I’ve decided to try something else. Soon I’ll replace it with a “Similar Websites” section, where I’d like to put banners and links to other websites that share content in line with my blog theme. One more good reason to use the mailto button: write me if you want your website linked on my blog! ūüôā

Differential Gear

Finally, this week I’d like to share with you a nice video about the¬†Differential Gear. As God Wikipedia says, “A vehicle’s wheels rotate at different speeds, mainly when turning corners. The differential is designed to drive a pair of wheels while allowing them to rotate at different speeds. In vehicles without a differential, such as¬†karts, both driving wheels are forced to rotate at the same speed, usually on a common¬†axle¬†driven by a simple chain-drive mechanism. When cornering, the inner wheel needs to travel a shorter distance than the outer wheel, so with no differential, the result is the inner wheel spinning and/or the outer wheel dragging, and this results in difficult and unpredictable handling, damage to¬†tires¬†and roads, and strain on (or possible failure of) the entire¬†drivetrain”. The differential solves all problems and its working principle is wonderfully explained by this video: enjoy it ūüôā

Rise of the Medical Machines


source: this website

Pier Cristoforo Giulianotti (University of Illinois – Department of Surgery) cannot foresee a time when robots replace surgeons, but he has no doubts over the importance of robotics: robot surgery is the future of medicine.

After some historical hints, a brief presentation of “five of the coolest robots in medicine” is proposed: Da Vinci System, Cyberknife, Neuroarm, Rp-Vita and Paro.

Click on the image on the right, here, to be redirected to the official webpage and read the whole story ūüôā

                                              Perspective of a patient

…is there a future… for human doctors? maybe in science fiction…

PhD positions at IIT in Genova, Italy

IIT and the University of Genoa have published a call for application to the next PhD course starting January 2014. This page is meant to help candidates navigate the large number of research themes as well as the online application forms. Prospective students are invited to read the call text carefully, read the available research themes and contact their respective proponents for more information. The deadline for applications is September 20th, 2013 noon (Italian time/CET).

The PhD offer is divided in “courses”. IIT covers four different courses, namely:


  1. Bioengineering & Robotics Neuroscience
  2. Science & Technologies of Material
  3. Chemistry
  4. Science & Technologies for Electronics and Telecommunication

Courses are internally divided in one or more “curricula”.¬†Each student must apply to at least one theme. Multiple applications are possible (albeit not encouraged) by repeating the file upload and submission procedure. Please note also that themes may repeat across curricula and joint tutorship across courses and between IIT and the University of Genoa is not rare. Prospective students are invited also to verify carefully the themes by contacting the relative tutor/tutors in advance (tutors and contact emails are listed for each theme).

Detailed information can be found on this webpage. Concerning the curriculum¬†Advanced Robotics and Robot Design, here’s a list of the proposed themes:

  • 8: Developmental Robotics And Robot Learning Of Motor Skills
  • 9: Robot Learning For Agile Locomotion Of Compliant Humanoid Robots (link)
  • 10: Human-robot collaborative manipulation and coordination in bimanual tasks
  • 11: Learning from demonstration in a soft robotic arm for assistance in minimally invasive surgery
  • 12: Bidirectional user interfaces for human-robot interaction (link)
  • 13: Automatic Tumor Segmentation and Classification in Real-Time Endoscopic Video
  • 14: Modular end-effectors for robot-assisted minimally invasive microsurgery
  • 15: Minimally obtrusive surgeon-machine interface for robot-assisted surgery
  • 16: Simulator and Training System for Laser Surgeries in the Larynx (link)
  • 17: Planning and Control of Highly Dynamic Full Body Motions for Robots With Legs and Arms
  • 18: Perception and Mapping on a Quadruped Robot (link)
  • 19: Development of a Reconfigurable Multifinger Robot for Packaging Applications (Robotic Origami)
  • 20: Exploration of Haptic Sensation and Its Use in Detecting Peripheral Neuropathy

SURGICAL ROBOTICS – 6th Summer School

September 4-11, 2013 – MONTPELLIER, Francemtp

Robotics enables surgery to be less invasive and/or to enhance the performance of the surgeon. In minimally invasive surgery (MIS) for instance, robotics can improve the dexterity of conventional instruments, which is restricted by the insertion ports, by adding intra-cavity degrees of freedom. It can also provide the surgeon with augmented visual and haptic inputs. In open surgery, robotics makes it possible to use in real time pre-operative and per-operative image data to improve precision and reproducibility when cutting, drilling, milling bones, to locate accurately and remove tumours. In both cases, as in other surgical specialities, robotics allows the surgeon to perform more precise, reproducible and dextrous motion. It is also a promising solution to minimize his fatigue and to restrict his exposition to radiation. For the patient, robotics surgery may result in less risk, pain and discomfort, as well as a shorter recovery time. These benefits explain the increasing research efforts made all over the world since the early 90’s.

Surgical robotics requires great skills in many engineering fields as the integration of robots in the operating room is technically difficult. It induces new problems such as safety, man-machine cooperation, real time sensing and processing, mechanical design, force and vision-based control… However, it is very promising as a mean to improve conventional surgical procedures, for example in neurosurgery and orthopedics, as well as providing innovative new ones in micro-surgery, image-guided therapy, MIS and Natural Orifice Transluminal Endoscopic Surgery (NOTES).

The highly interdisciplinary nature of surgical robotics requires close cooperation between medical staff and researchers in mechanics, computer sciences, control and electrical engineering. This cooperation has resulted in many prototypes for a wide variety of surgical procedures. A few robotics systems are yet available on a commercial basis and have entered the operating room namely in neurosurgery, orthopedics and MIS.

Depending on the application, surgical robotics gets more or less deeply into the following fields: multi-modal information processing; modelling of rigid and deformable anatomical parts; pre-surgical planning and simulation of robotic surgery; design and control of guiding systems for assistance of the surgeon gesture. During the Summer school, these fields will be addressed by surgeons and researchers working in leading hospitals and labs. They will be completed by engineers who will give insight into practical integration problems.

This course is addressed to PhD students, post-docs and researchers already involved in the area or interested by the new challenges of such an emerging area interconnecting technology and surgery. Basic background in mechanical, computer science, control and electrical engineering is recommended.

Coordinated by:

  • Philippe POIGNET & Nabil ZEMITI –¬†LIRMM, CNRS ‚Äď Universit√© Montpellier 2
  • Renaud GARREL –¬†Universit√© Montpellier 1, CHRU Montpellier, ENT Dpt