Deleting multiple Values in an 2D-Array

[Nikolai Huckle]

Hi everyone,

I have two 200000x1 Arrays which I plot against each other. I have attached an example image. 
The issue I have is, that I only want the outline of the point cloud: the farthest points to the right, the left and upwards. 

The first step I did(which im not sure is needed), was to delete all the multiple occuring value pairs, but this already has proven to be difficult as I cant vectorize the code which i used.
And the calculation takes too much time(see attached .m-File).

If anyone has an idea or a hint in the right direction on how to achieve this(either the deleting of multiple values or the outline point), I'd greatly appreciate it.
Thanks in advance for any help.

Kind regards,

Nikolai

EJAJ.pdf
Description: Adobe PDF document

snipEJAJ.m
Description: Binary data