[Kwiver-users] Bounding Box Issues

[Matt Leotta]

Matt,

It sounds like maybe we need to check "isEmpty()" on the box before
computing the area, and return 0 for empty boxes.

By the way, I'm not a fan of having this bounding box class in KWIVER that
simply wraps Eigen::AlignBox, but only exposes a subset of its functions.
I think we should just use Eigen::AlignBox and possibly some typedefs for
it if we want to call it "bounding_box".  Or we could derive a subclass if
we need to add some additional methods.  There is no reason to hide all the
other functionality of AlignBox.  This is a separate discussion to have
some time.

--Matt

On Sun, Mar 10, 2019 at 10:43 PM Matt Brown via Kwiver-users <
kwiver-users at public.kitware.com> wrote:

> I was diagnosing an issue in a detection pipeline doing non-maximal
> suppression that led me to observe that the area of the intersection of two
> bounding boxes can be negative.
>
> The intersection
> <https://github.com/Kitware/kwiver/blob/master/vital/types/bounding_box.h#L276>
> of two bounding boxes yields a bounding box representing the intersection.
> Internally, the bboxes are Eigen::AlignedBox, and the intersection uses this
> Eigen function
> <https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwiy1cj8hfngAhWnhOAKHRrsCtcQygQwAHoECAEQBg&url=https%3A%2F%2Feigen.tuxfamily.org%2Fdox%2FclassEigen_1_1AlignedBox.html%23title26&usg=AOvVaw1oBy2fk1j2WCPGlEGJnXOn>.
> Still working on it, but I suspect that Eigen is returning an empty box
> with junk for parameters (i.e., Eigen says "The result of most methods is
> undefined when applied to an empty box").
>
> So the question is, what should be returned here
> <https://github.com/Kitware/kwiver/blob/master/vital/types/bounding_box.h#L279>
> when there is no intersection? Should we define a special empty bbox
> subclass?
>
> Best,
> Matt
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