I'm still looking for a solution. I have a fuzzy idea. Please, someone, tell me that I'm wasting my time and there's already a well established solution for this problem.

My idea is that since we have only these 3 degrees of freedom we should use that and somehow add constraints. Or in other words, since the robot can only move on a flat surface then the solution doesn't have to be as comprehensive as 3-dimensional #HandEyeCalibration. Even though the camera looks at a 3d space, the target, if it's fixed in place, or more precisely, the measurements of it make up a 2-dimensional plane in that space. From those measurements we can find the equation of that plane in the camera coordinates. Which will give us the roll and pitch of the camera mount.

However, we don't know the yaw yet. We can't be sure if the camera is looking exactly forward, or at what angle, relative to the robot's kinematics. To find the yaw we would have to match the set of points where the camera saw the target with the points where the robot thought it was at that precise moment. Both sets of points are 2-dimensional. So matching them should be similar to or exactly finding a #homography between the two planes...

Would that homography matrix also hint us about the offset from the robot drivetrain's kinematic center and the camera mount?

🤔

#FIRSTrobotics #FRC #CameraCalibration #SightAlignment

Except for naming the shapes I figure something like following might work?

- Render each Unicode script in several fonts.

- Training per-script classifiers (OCRs) on those.

- Run the per-script classifiers on each others training data to identify homographs.

There's a tricky bits, like creating non-confusable out-of-script scribbles to include in training data, etc.

Still... this doesn't seem like all that impossible?

What am I missing?

#unicode #homography #ml #classifier

You know what should exist?

A Unicode Codepoint => basic shape map.

Ie. something that would tell you that Greek Ο, Latin O, and Cyrillic О all have the same basic shape - and ideally give it a name, like FULL_UPRIGHT_OVAL.

EDIT: I completely ignored massive glyph variation. Please read "shape" as "category of things that sometimes render similarly". So "a" would map to a category that includes things similar to both single- and double-story a.

#unicode #homography

CNC Toolpath Visualisation With OpenCV

[Tony Liechty] has been having a few issues getting into CNC machining -- starting with a simple router, he's tripped over the usual beginners' problems, you know, things like alignment of the design to the workpiece shape, axis clipping and workpiece/clamp collisions. He did the decent hacker thing, and turned to some other technologies to help out, and came up with a rather neat way of using machine vision with OpenCV to help preview the toolpath against an image of the workpiece in-situ (video, embedded below.)

ChArUco (a combined chessboard and ArUco marker pattern) boards taped to the machine rails were used to give OpenCV a reference of where points in space are with respect to the pattern field, enabling identification of pixel locations within the image of the rails. A homography transformation is then used to link the two side references to an image of the workpiece. This transformation allows the system to determine the physical location of any pixel from the workpiece image, which can then be overlaid with an image of the desired toolpath. Feedback from the user would then enable adjustment of the path, such as shifts, or rotates to be effected in order to counter any issue that can be seen. The reduction of 'silly' clamping, positioning and other such issues, means less time wasted and fewer materials in scrap bin, and that can only be a good thing.

[Tony] says this code and setup is just a demo of the concept, but such 'rough' code could well be the start of something great, we shall see. Checkout the realWorldGcodeSender GitHub if you want to play along at home!

We've seen a few uses of OpenCV for assisting with CNC applications, like this cool you draw it, i'll cut it hack, and this method for using machine vision to zero-in a CNC mill onto the centre of a large hole.

#cnchacks #charuco #cncrouter #homography #image #opencv