Activity 17: Basic Video Processing

The task: to perform basic video processing to obtain kinematic constants/variables.

The process:
We made short video clips that demonstrate simple kinematic motion. Marge Maallo, Julie Ting and I made a video of a glass marble bouncing off the floor after being dropped from a certain height then measured its coefficient of restitution. The coefficient of restitution of an object is a fractional value representing the ratio of velocities before and after an impact given by the following equation:

where h is the bounce height and H is the drop (original) height.

The program VideoHub was used to parse the original .avi file into .jpg images. Below is a sample of the image obtained from VideoHub after being converted to greyscale.

greyscaled image of marble in its "drop" position

As can be seen in the image, one problem was the orientation of the camera when we took the video. To fix this Scilab was used to obtain the angle at which the camera was tilted, and then Gimp was used to manually rotate the images then crop them.

(a) (b)

cropped images of the marble in its drop (a) and bounce (b) positions

The distance of the marble from the floor was measured and we obtained
h = 62 pixels
H = 66 pixels

applying the equation for coefficient of restitution, we obtain:
coefficient of restitution = 0.94


**I give myself a grade of 8 for this activity because although the desired kinematic variable was obtained, a sizeable part of the process was done manually.

**acknowledgement goes to my groupmates in this activity, Julie and Marge. The equation and definition for Coefficient of Restitution (COF) were obtained from Wikipedia.