Matlab tutorial course

Exercises 2:

Exercises• Copy the script ‘face_points.m’ from my webpage into your ‘scripts’ folder• Create a new folder in your MATLAB folder called ‘data’• Copy the file ‘face_points.mat’ from the ‘data’ folder on my webpage into

the folder you’ve just created– Run the script, look at the figures it produces

• Now go through the script line by line– Can you work out what each line does? The comments should help!– Make a note of all the variables assigned to– Make a note of all the functions called– Make a note of when and how arrays are indexed and assigned– Make a note of where element-wise or matrix processing is used

Exercises• Try modifying the script changing pt_xy or changing how much the face is rotated by• Change the script into a function that takes ‘pt_xy’ and ‘theta’ as input arguments• Change this function so that it produces output ‘min_dist’ – the minimun distance

of ‘pt_xy’ to a point on the face• Use your new function to answer the follow questions:

– If pt_xy = [40, -50], which point on the face is it nearest too?– How far is it from this point?– Generate a plot of the face upside-down - save this figure:

• Click ‘File’ -> ‘Save as’• Change ‘Save as type’ to ‘Portable Network Graphics file (*.png)’• Give it a suitable name and click ‘save’

• When you’ve tried writing your own function, you can download mine for a sample answer

• And if you’re wondering what this has to with image, check out this video on youtube of a mobile face-tracking app developed in this department in 2010– https://www.youtube.com/watch?v=5TDO9ok4sWI