Gait pattern.pptx

Gait pattern and its fundamentals used in forensic.

1. Gait Pattern By : Lad Matangi

2. Footprint Foot print is a general forensic term used for barefoot print or impression and shoe print. The human foot is highly individual in its from, size & shape. This feature originate and initially influenced by an individuals genetic code. Gait Pattern Gait is the medical term to describe human locomotion or the way that we walk. And this locomotion achieved through the movement of limbs. And pattern of foot form due to locomotion called as Gait Pattern. Human Gait is defined as bipedal, biphasic forwad propulsion of center of gravity of human body in which there are alternate sinuous movement of different segment of the body with least expenditure of energy. Different type of gait pattern characterized by different limb motion.

3. This gait pattern deepens on overall velocity, forces ,kinetic and potential energy cycle and change in the contact with the surface. Gaits can be classified into two groups : -Natural gaits -Specialized gaits Natural Gaits : every human will use without special training . Specialized Gaits : People train to use under specific condition & situations. Forensic gait analysis is defined as the identification of person by their gait or feature of their gait and usually from CCTV footage & comparison of footage of known individual. It is use in forensic for prison security and criminal identific –ation. Types of Gait :-Walking -Crawling -Jogging -Running

4. History The pioneers of scientific gait analysis were Aristotle on animal. In 1890, Christian Wilhelm Braune and Otto Fischer published a series of paper on biomechanics of human gait. Eadweard Muybridge and Etienne Jules Marey were the pioneers of gait pattern with help of photography in 1900s. In 1970 Began start using video camera system for analysis. Development & use of modern computer based system was started in 1970-1980. In India gait pattern analysis first time used by Khojies or Trackers of north India typically found in Punjab. They traced stolen cattle's [ Kori or pyra] by their footprints. The Punjab Khojies was similar to the Paggi of Gujarat . After that they used foot prints for the identification of crimals.

5. Gait Cycle Gait cycle is used to describe the complex activity of walking by describing the motions from the period of time from one heel strike on the ground to next strike of the same heel, on the ground for a second time. Stevenage et al proof that the legs motions use to identify a person. The method can be successful for video analysis. The Gait Cycle consist of three task: 1.Weight Acceptance. 2. Single limb support. 3. Limb advancement.

6. Gait Cycle is divided into two phases : 1.Stance phase 2. Swing phase 1.Stance phase : Defined as the interval in which the foot is on the ground . [60% of gait cycle] It beings at the instant that one extremity contacts the ground & continuous only as long as some portion of the foot is in contact with the ground. Stance phase divided into : Heel strike to foot flat Foot flat through mid stance Mid stance through heel off Hell off to toe off 2.Swing Phase: Defined as the interval in which the foot is not in contact with ground.[40% of gait cycle] It begins as soon as the toe of one extremity leaves the ground & ceases just before heel strike or contact the same extremity. In this phase in forward motion.

7. Sub division 0f phases Stance phase: Heel strike [Initial Contact] Foot flat [Loading Response] Mid-stance [Mid stance] Heel off [Terminal Stance] Toe off [Pre Swing] Swing phase: Acceleration [Initial Swing] Mid-swing Deceleration[Terminal Swing]

8. Gait Cycle

9. Gait Pattern Analysis The gait pattern is analyse follow : Gait Line Direction Line Foot Line Foot angle Principle angle Step width Step length or stride

10. Direction Line[DL] :- It is an imaginary line which indicate the direction in which person is walking .It is straight line . Gait Line [GL] :- In normal person walk the gait line coincides with the direction line& runs along the inner sides of both heel prints. Foot Line[FL] :- It is straight line running through the longitudinal axis of the foot print. - A line which is passes through the second toe of the center of he heel. - Its inclination to the direction line shows the angle at which foot is put down. Foot angle [FA] :- The angle between the foot line & the direction line known as the foot angle. - The foot angle of man is often larger than that of women . -The normal foot angle is 30-32 degree. Principle angle[PA] :- Angle between foot line of two feet & thus the sum of the two foot angles.

11. Step width [SW] :- The distance between the parallels drawn in the direction of the direction line touching the inner sides of right and left foot heel. Step length or stride [SL] :- Distance between center of two successive heel print .It depends on the size of walker, his habits, and his speed. The step length varies from 20-40 inches.[27 inches for slow walking &35 inches of fast walking person.

12. Factors affecting variables Age Gender Height Size & shape of bony components Distribution of mass in body segments Joint Mobility Muscle strength Types of clothing & footwear Habit Psychological status

13. Gait Recognition Under forensic science, gait is study through forensic gait analysis which includes identification of gait features and patterns of subjects seen on CCTV and from foot prints forming a gait pattern left at scene of crime. The height of individual can be determine by his/her footprint and shoeprint ,as the foot tends to be approximately 15% of the persons average height. Two type of gait recognition techniques: 1.Automatic analysis of video imagery 2.Radar system 1.Automatic analysis of video imagery : Video sample of the subjects walk are taken and the movement of joint and angle over time are analysed. A mathematical model of motion is created & is subsequently compared against any other samples in order to determine their identity.

14. 2. Radar system : This method is used by police officers to identify speeding cars. The radar records the gait cycle that the various body parts of the subject created and compared against other sample to identify them. Now a days due to increasing use of closed circuit television [CCTV] the criminals will be recorded committing crimes or recorded while they are departing or arriving from the scene of crime. The investigator not able to identified person in video by facial features . In this case a forensic podiatrist able to link a suspect to the criminal act by analysis and comparison of his /her gait. There are many method for detection of gait pattern.

15. Gait based person verification system for Forensics This is the first gait based person verification system that can analyze the gait for forensic science is presented. Recently CCTV are used all around the world which capture video & this CCTV footage use as digital traces for forensic science. If in footage face of perpetrator was not observed then with the gait pattern person can identified. This system used in forensic science carried out identification of person without the help of gait specialist Characteristics of this system : It provide professional analysis of gait information Easy for who is not specialist in gait analysis The system output an objective value Applicable to various crime scene

16. Construction of system

17. Data Flow

18. Modules of system : 1.Subject registration Module : A user enrols gait data and select subject whom he/she interested in as a target subject with bounding box as a region of interest in each image frame. 2.Silhouette creation module : Make silhouette emergence from the selected target sequences. A background is subtract and graph cut based segments are implemented and available. 3.Gait verification module : In this module a user select two silhouette image sequence to be compared. The gait pattern extract from the two image sequence and compared. If the subject is wearing helmet or bag, then a function feature masking used. And probability calculated.

19. References: Book : Forensic Science in criminal Investigation & Trials 4 th edition [By: Dr. B.R.Sharma] University Institute of Legal studies ,Punjab University, Chandigarh.[Journal] Webeography : http://en.wikipedia.org/wiki/Gait%28human%29 Policechiefmagazine.org