So I had a thought about two days ago that I have been working on. The Holey Calibration has two squares that look like this:

```
Point 1 * --- M1 --- * Point 2
|\ /|
| M6 M5 |
| \ / |
M3 X M4
| / \ |
| / \ |
|/ \|
Point 3 * --- M2 --- * Point 4
```

Now that is actually one more measurement than we need to affix all of those points on an XY coordinate plane.

So I thought, what if I placed all of these points using 5 of the measurements and then calculated the missing distance from these points and compared it to the unused 6th measurement. My thought was if I repeated that 6 times, I could find the most outlier measurement. This could be used to prompt users to check what appears to be the worst measurement.

Except, I donâ€™t think it works â€¦ I think my premise is wrong.

Sadly, I built all of the work already, it was at least a good refresher on deriving geometric functions again (Law of Cosines, Intersecting points on two circles).

The results I get look like this:

```
{'M1': -4.769083263379116,
'M2': -4.768156399617851,
'M3': -6.492332606734294,
'M4': -6.444498656751762,
'M5': 3.840564042951428,
'M6': 3.8360705815812253}
```

Where the number reported is the measured distance - the distance derived from plotting the points using the other measurements.

What I think I discovered, is that even if it is only one bad measurement (and it never is) I canâ€™t discern which is bad. If the bad measurement is included, then the error calculations of all of the other measurements look bad. And when the bad measurement isnâ€™t included, its error calculation is high because, well it is an error.

Anyways, **is there something I am missing?** Could one actually learn anything from doing these calculations.

Also, my errors seem very odd to me. It is entirely possible I have made some math mistake. Related lines all look very similar to each other. Plus the error amount which should be in mm seems way too high. I could be off my a mm on some measurements at worst, but I would be surprised if it averaged to even that high.