It strongly depends on your notion of "ok" ;-)

The last line, in the very least, gives me headaches. Do you really want to return 7 references from a subroutine and remember what they are and in which order?

I'd suggest the usage of a hash ref instead:

return {
    metadata => $hashref,
    above    => {
        x => ...,
        y => ...,
    },
    below    => {
        x => ...,
        y => ...,
    },
    on       => {
        ...
    },
};
[download]

As for the mathematics involved I didn't see a flaw. But you should test it nevertheless, with small sets of selected data.