Identification of the coordinates of the outer edges of a part to be printed in 3d

Hi, how can I do this in matlab?

"given a g-code to manufacture more parts (a, B, cv, Pippo), first of all it is necessary to declare which part to analyze, and then extract the outer edges, i.e. the X Y Z coordinates "

This is for each layer to be printed. I thought about considering a boundary box with maximum coordinates Xmax and Ymin and starting from this