
Building a Crystal Clear Whiteboard - hepha1979
http://hackaday.com/2013/11/22/building-a-crystal-clear-whiteboard/
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WestCoastJustin
Example of the board in action @
[http://peshkin.mech.northwestern.edu/233/056_RCcircuits2.htm...](http://peshkin.mech.northwestern.edu/233/056_RCcircuits2.html)

Lightboard: construction, electronics, lighting, parts list, and improvements
@
[https://sites.google.com/site/northwesternlightboard/home](https://sites.google.com/site/northwesternlightboard/home)

The setup will cost about $10-15k along with some elbow grease, which probably
isn't that much in this type of setting, especially if you are creating high
quality videos which are timeless.

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rwmj
_Everything he’s writing is backwards. That’s not actually a problem in this
case as [Michael] uses flip teaching._

But flip teaching is nothing to do with writing backwards, or at least not
according to the linked Wikipedia article. So he is actually writing
backwards?

Edit: Ah I see, _the whole scene_ is mirrored, including him. I guess that
could work, although then diagrams really have to be drawn backwards (assuming
western L->R convention), and any computer generated text will have to be
projected backwards on the whiteboard.

~~~
bradleyland
There are a couple of factors coming together here that require some
explanation in order for the individual parts to make sense.

Everything he writes appears backwards because he's facing us as he writes.
Hence, someone standing in the room would see everything in reverse.

This isn't a problem because he uses flip teaching, where students view a
video of the lecture at home. This only becomes clear if you read the details.
The camera he uses to record his lecture does so through a mirror, so the
image is reversed by the mirror, not by software.

Also, overlays need not be reversed, because they aren't projected anywhere.
They're composited in to the video stream by a switcher.

All of this becomes clear if you read the creator's write up on how to build
one. I'd highly recommend it:

[https://sites.google.com/site/northwesternlightboard/home](https://sites.google.com/site/northwesternlightboard/home)

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ChuckMcM
This is so cool. I realize that it doesn't look quite that cool in person but
am definitely interested in seeing about building one.

I'm now wondering if we could add LED lighting to the top of our sliding glass
door by drilling holes down to the edge of the glass and installing 1W LEDs.

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kyzyl
I suspect your sliding door will be made of multi pane glass filled with
argon. that probably won't work too well. in order for total internal
reflection to work well the glass needs to be pretty homogeneous, so that the
wave fronts are all parallel. that requires a nice straight, flat, unscratched
surface and uniform refractive index. hence sapphire.

also, he uses thick glass so as to catch the led light. since power leds don't
distribute their power very narrowly, it will be tricky to get a large
fraction to start transmitting down a thin plate of glass.

it could be made to work but it just will be harder / not as good.

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Raphmedia
" In order to get the text to read the correct way he just bounces the camera
off of a mirror. "

... couldn't he simply flip the output?

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driverdan
Using a mirror allows him to live stream without processing.

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dllthomas
Sure, though "flip the incoming image" isn't a lot of processing and can
certainly be done "live".

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mbreese
He is also merging images together, so he'd need to run the raw (unflipped)
feed through a video processing program, and then back out (flipped) to his
video switcher, and then capture that stream back. The switcher is how he adds
video or powerpoint slides to the talk. It's really the video switcher that
makes this whole thing a minimal post-production affair. So instead of adding
another computer to the mix, he solves the problem with a $25 mirror that
isn't very difficult to troubleshoot.

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msutherl
This could all be done in software like Max/MSP very easily, no hardware
necessary except for capture cards, assuming the video cameras don't already
stream over USB.

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sitharus
Yes, but mirrors crash a lot less often than software.

~~~
dllthomas
7 years bad luck when they do, though.

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angersock
There's also the classic DIY whiteboard recipe for those of us who are very
cheap/not yet funded:

Get a 4x8 sheet of shower board from Home Depot. It's basically just a thin
piece of melamine, and should be like 8 bucks.

Get a 4x8 sheet of really low grade 3/8" or 1/2" cedar chipboard (like that
used in flooring), again maybe 3-4 bucks.

Glue the former onto the latter with Liquid Nails, probably 2-3 bucks a tube.

Works great, erases, and when it finally gets too gross to use (in about a
year), you replace it for another fifteen bucks.

~~~
oasisbob
Slightly more expensive, an IKEA hack for a glass whiteboard:

[http://www.ikeahackers.net/2012/01/not-expensive-glass-
white...](http://www.ikeahackers.net/2012/01/not-expensive-glass-
whiteboard.html)

More expensive than showerboard, but it's glass -- so it erases forever and
looks great. The % savings compared with commercial glass whiteboards is
astronomical.

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Already__Taken
If anyone considers this, please us tempered glass. This says 'tabletop' so I
assume it is. It's not a whole lot more expensive but it's much less deadly.

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bgraves
Many example videos of this Lightboard in use by its creator.

[http://peshkin.mech.northwestern.edu/233/](http://peshkin.mech.northwestern.edu/233/)

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beachstartup
wait... did anyone catch how he superimposed the powerpoint slide onto the
screen/glass/whatever? it's not in the video or the page text.

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BrentOzar
> wait... did anyone catch how he superimposed the powerpoint slide onto the
> screen/glass/whatever? it's not in the video or the page text.

Yeah, in his construction page, he explains that he uses a video switcher.
It's way more complex than it sounds - he's combining feeds from the camera
plus a computer into the final output, which is easy enough, but then he needs
to be able to see where he's drawing - because that projected image doesn't
actually show up on his light board. So he has a monitor on the other side of
the light board that he CAN see, but then it produces reflections on the light
board, so he starts in with polarizing filters.

[https://sites.google.com/site/northwesternlightboard/home/el...](https://sites.google.com/site/northwesternlightboard/home/electronics)

~~~
mbreese
And he uses a black background on the Powerpoint slides so that they are
superimposed properly and look like they are in the same space as the board.
Plus, he can then still use the fluorescent markers to "draw" on his slides
from the glass-board.

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dmritard96
totally one of my favorite profs in school - made the synthesis of
cs/electronics/mechanics seamless in students heads

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jcutrell
I did this with an Ikea tabletop and some shelf hangers while I was at GaTech.
The shelf hangers framed the glass tabletop on a concrete wall. Albeit not a
standalone board, it also had the ikea led strip. It worked well for me to map
out ideas on, and fit nicely on my wall at home.

I think I came out of the project at around 150 bucks.

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lnanek2
Some silliness going on here. OK, it's clear, he can look through it and see
his students reactions as he writes, OK. The writing is backwards so no one
can read it direct, it is shown by camera flipped. Then there's no point in
all the extra stuff to make the lines fluoresce since it is unreadable
unaltered anyway. He just needed a clear touch surface, which is common anyway
since we slap them on top of LCDs in countless products. Making the unreadable
lines bright is actually a disadvantage, since they are unreadable and they
are blocking the sight between the parties.

~~~
joezydeco
From TFA, this is just a means to produce nice looking videos to teach his
lessons.

His students watch the videos at home, then the classroom time is for doing
the homework with the teacher available for firsthand assistance. That is the
_flip teaching_ described in the article, which is being confused with the
reversed-screen being shown in the picture.

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i386
I hate writing on glass whiteboards. If the markers are not strong enough, you
can't see what you are writing over the glare of the lights.

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mseidl
I made one for myself, just spent 45$, 40$ for a desk protector from ikea, and
some mirror mounts, and mounted it to my wall.

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critium
Just add a kinect and you have your minority report interface!

