Finding vertices of a non-rectangle

[alec.heif]

Our team is attempting to use the Axis 206 camera with a ring light mounted to it to detect the quadrilateral formed by the retro-reflective tape and use coordinates from that, combined with knowing our robot's current heading from a gyroscope, to find our position in 3D space and distance to the hoop. (I say quadrilateral instead of rectangle because we want to be able to calculate distance to the target from positions other than right in front of the basket and perpendicular to the alliance wall, which means that the image we see will likely be distorted into some sort of trapezoid).

We have managed to find the quadrilateral, and can use the particle analysis tool to find the X and Y coordinates of its center of mass. What we have been unable to do is find the coordinates (in pixels) of the four vertices that make up the trapezoid. The "Particle Analysis" block in LabVIEW allows us to find the vertices of the bounding box that encloses the outer edges of the trapezoid (forming a rectangle), but so far we have been unable to find any way to get the four vertices of the trapezoid. Is there something I'm missing here?

Thanks a bunch!