Building a Crystal Clear Whiteboard | Hacker News Reader

Building a Crystal Clear Whiteboard

hackaday.com

219 pointshepha197944 comments

Example of the board in action @ http://peshkin.mech.northwestern.edu/233/056_RCcircuits2.htm...

Lightboard: construction, electronics, lighting, parts list, and improvements @ 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.

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.

He just writes normal. But it would be backwards to his "students" so he has to flip it somehow.

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

"Flip teaching" means that the lectures are recorded and made available online beforehand so that time in-class can be used for more interactive activities.

It doesn't have anything to do with his orientation to the viewer, and in fact does not even solve the issue of orientation because his setup even allows for live streaming of lectures.

It's actually fixed with a simple mirror: https://a970e7ea-a-62cb3a1a-s-sites.googlegroups.com/site/no...

The camera is actually looking at a mirror facing the scene, and in the mirror the image is flipped, so it records 'flipped'.

He's writing forwards, and if you look closely at the hackaday shot with the scene + lighting it appears backwards from that perspective.

Right, but in this case, the "flipped" part doesn't refer to the mirror. He isn't teaching his students this material live. He is recording lectures for them to watch before "class" starts. Then, instead of lecturing for an hour, he is there to answer questions, help with homework, etc...

The reason why the fact that he is writing in reverse isn't a problem is because his students never see him writing in person - it's all done via video.

It would be cooler if it can be flipped back to the audience.

" 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?

We did this for a school project. Found a large window on campus, wrote on it, then flipped it in a video editor. I guess if he is trying to go with zero post processing a mirror would work.

Using a mirror allows him to live stream without processing.

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

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.

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.

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

7 years bad luck when they do, though.

Most cams allow you to flip recording itself. No post processing needed. Simply activate "mirror" in your camera's settings.

ffmpeg can flip a video stream in realtime.

There's no such thing as live streaming without processing. The amount of additional processing needed to flip an image is so tiny as to be unworthy of consideration.

Adding a mirror is not much work either.

No, but it's likely more work, when you consider the hassle of setting it up and aligning it physically, vs simply using a camera that has a mirror function built in.

The mirror cost $25. This is a $10k+ setup. Why go through that effort?

He could have learned mirrored writing. Would have allowed using the board in in-person lectures. Not that simple, but definitely possible: after 2 weeks of 2-hour almost-daily practice I've acquired quite decent skills at that.

I was sitting face to face at a table with a contact at my bank and all the time she was writing the numbers and diagrams facing me. I said that i was very impressed with her writing so he told me that writing backwards was actually part of their standard training at that bank, because they all have to write things on paper while facing customers like this so often :)

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.

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.

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

http://peshkin.mech.northwestern.edu/233/

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

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.

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.

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.

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.

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.

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

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.

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

http://www.ikeahackers.net/2012/01/not-expensive-glass-white...

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

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.

We did exactly this for a coworking space in town.

I suggest using a full-length bracket all along the top and bottom and siliconing the tabletop into place, and then putting little brackets on the sides.

Thanks for the awesome link, I'm surprised I missed this Ikeahacker post. I might have to bring a dry erase marker along on a future trip there. I'm definitely going to do this for a future home office upgrade. Now I just need plan out some kind of dead simple rig for taking photographs of the whiteboard that would automatically sync with either Dropbox or Evernote. This might be a good use for one of my old android phones.

You don't need the chipboard backer if you just screw it to the walls at each stud (every 16" here in the US). Have sure you do both the top and bottom though, otherwise humidity may warp the board away from the wall (I'm looking at my first attempt as I write this which has warped, my second which I screwed on both top and bottom has not)

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.

This is bordering on blogspam. If you read the actual creator's write-up, there is a LOT more detail.

https://sites.google.com/site/northwesternlightboard/home

> 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...

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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