Tracking Rectangles

[JewishDan18]

Originally Posted by mikegrundvig

The whitepaper is extremely useful but the part I needed help with is actually what's glossed over the most. My understanding is that it's fully possible to determine both angle and distance from the target by the skew of the rectangle and the size. Here is a quote from the whitepaper:

"Shown to the right, the contours are fit with lines, and with some work, it is possible to identify the shared points and reconstruct the quadrilateral and therefore the perspective rectangle"

Except it stops there. Have any other reading or direction you can send us to take this the rest of the way? I'd really like our bot to be able to find it's location on the floor with the vision targets and unless we are straight-on, this is going to require handling the angle. Thanks!

-Mike

This varied depending on which language you use. If you aren't using Java, you should have access to a "convex hull" function, and a "find edge" function, which should do what you want. I haven't tested this yet, as I am using Java and do not have these functions. I'm working on getting them implemented in Java, but I have bigger fish to fry at the moment.

In theory, the bounding rectangle should be enough, if you put your camera as high as possible, and are willing to tolerate a little error. The height would tell you how far away you are, and the width, after accounting for the height, would tell you how far "off center" you are, giving you your position in polar form relative to the target. The error would be greater the further off center you are (since the perspective transformation makes the rectangle taller than it should be), but I would need to test to see if it is a significant amount.