Farther or further?

Dear LingQ fellows,
I’ve wrote this:
" Finally, accepted parallelograms are combined into one by selecting the FARTHER coordinates from image borders which, in most cases, corresponds either to the smallest parallelogram or the interception among them."

But one person told me he would use FURTHER instead of FARTHER.
I intended to say that I would chose the coordinates that are more distant from the image borders.
What do you think about it? Should I use farther or further?

Comments from anyone are welcome!

Thanks, twhite!
My feeling was for using farther, but my colleague is older and more experienced than me, so I suspected my intuition was wrong. I didn’t remember that idea of physical distance, but now I have a concrete argument to convince him!