

Turning a Wii Balance Board into a net-enabled bathroom scale - StavrosK
http://www.stavros.io/posts/your-weight-online/?

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johnpmayer
What's so striking to me is that the barriers to prototyping these peripherals
for general purpose use has been lowered significantly. It was not long ago
where it took days of hacking to connect a Wiimote to your PC, and even then
you probably wouldn't get full functionality.

Good work and thanks for sharing!

(also, obligatory "now the NSA can estimate if they can chase you on foot")

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StavrosK
They'll never catch me! Muhahaha!

Seriously, though, that's because many people have put many hours of work into
reverse-engineering protocols and writing libraries, which is fantastic.

This wouldn't be a two-hour job if so many people hadn't open-sourced their
work.

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smokey_the_bear
This is neat.

Sort of relatedly, I bought the Withings Wifi scale about a year ago, which
does the same thing. I really like it. It is easy to go back and look at
weight trends without having to obsess too much about the number each day.

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StavrosK
Yeah, exactly. My normal scale was missing the big picture of how my weight
fluctuates month-to-month. I do need to implement some smoothing, though, as
the raw daily value isn't as useful.

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billrobertson42
Daily weigh-ins can be very consistent if you weigh yourself in the morning at
about the same time after using the toilet, and before eating/drinking
anything.

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StavrosK
Well, it looks like they vary by -+0.5kg, since this is what I'm doing here:
[http://www.stavros.io/misc/weight/](http://www.stavros.io/misc/weight/)

That's why I want a smoothing algorithm, but the one I found here[1] is giving
me a bit of a problem (I can't see why the data points are being squeezed).

[1] [http://www.swharden.com/blog/2008-11-17-linear-data-
smoothin...](http://www.swharden.com/blog/2008-11-17-linear-data-smoothing-in-
python/)

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billrobertson42
Relative to your overall weight, that doesn't seem like it's highly variable,
but I've never been much for stats. Try weighing yourself daily after dinner
and see the difference.

How much water do you drink per day? I have found that in times where I'm not
drinking enough water, my weight will fluctuate more.

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StavrosK
Nah, it's not that variable, it just fluctuates a bit. By "it's not as useful"
I mean that weight loss/gain happens at larger timescales, so you can't look
at normal daily noise and say "omg im so fat".

I think the noise has more to do about the time you last drank water (right
before bed, for example), also the time you last ate (the later you eat, the
more food you'll still be digesting when weighing yourself). It's not a
problem by any stretch, it's just normal data variance.

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ekianjo
This is a great example of innovation at work. And I really like the fact that
he removed several dependencies from the existing solutions. You have to love
that :)

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StavrosK
Yeah, I think they were a bit unnecessary. The original author was using
pygame for event notification (a queue would probably be enough) and a thread
to receive the events. I just switched it to call methods on a different
class, hopefully it will be more useful to people now!

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anjc
Excellent work. How accurate is the weighing with the averaging that you seem
to be doing?

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StavrosK
I'm only doing histogramming, so, as long as you don't move a lot, it's pretty
accurate. The most frequent value will have 100 samples logged and the second
most frequent will have 20, so that's quite the difference. I will compare it
to my normal scale when I get back home, but it seems to consistently have a
+1kg from that one (a Tanita something).

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smtddr
Sort of related, the newer WiiFit U coming out Nov 1st will have social
features while trying to lose weight with others online
[http://wiifitu.nintendo.com/](http://wiifitu.nintendo.com/)

I'm just posting it here because I really[1] like WiiFit and I hope others
give it a try, you can truly get a workout from it and lose weight. I hope to
make a cool promo vid or something about WiiFit U.

1\.
[http://blog.sanriotown.com/minusworld:hellokitty.com/2011/06...](http://blog.sanriotown.com/minusworld:hellokitty.com/2011/06/19/wiifitplus-%E3%81%AF%E3%81%84/#more-41)

