Physics Department Lightboard Design
Built by John Mocko
This Lightboard design is based upon the open source instructions posted by Dr. Micheal Peshkin at Northwestern University. However, I have extended his original design to include not only the Lightboard but also the ability to simultaneously record the Lightboard PLUS a live computer screencast from a Smart Podium Monitor with the ability to use an electronic pen to write directly on the screen. This is possible by using the Mediasite system by Sonic Foundry, either through the Mediasite Desktop Recorder Version 2 software or with a Mediasite dedicated recording box. This means that instructors can record Lightboard lectures alone that include built in computer graphics in the final video just as Dr. Peshkin does. However, instructors can also decide to include direct recording of an additional live computer screencast of a second computer in combination with the Lightboard. Students viewing the online recording through Mediasite can simultaneously see the Lightboard with its computer graphics PLUS a second video of an additional computer screen with its graphics as well. In addition, when the students view the final lecture recording they can switch freely back and forth between the Lightboard video and the second simultaneously synced computer screencast video. Because this system can record the second computer screencast in real time I was able to add a Pasco Data Acquisition system to that computer along with a second keyboard, mouse and mirrored monitor to create an experiment recording area. Using the Pasco system I can attach sensors of all kinds to the computer for Physics, Chemistry, Engineering, Biology and Earth Science and record live data in graphs, digits or charts for the online students to see. This system can also export the data as a spreadsheet for online students to analyze at home. It even has video analysis functionality built into the Pasco software that online students can use at home to pull data directly from the video……all of which may be used to create online labs if desired.
Example Videos: These videos were recorded to show off the capabilities of the system. My wife, Megan Mocko, is a Master Lecturer in the UF Statistics Department and she is featured in the videos. The audio in these videos is a little over driven and it has since been fixed in the system.
Lightboard PLUS Computer Screencast : Notice in this video there is a circular pair of arrows in the upper right corner of your screen that allows you to swap views between the computer and the video.
Lightboard PLUS Live Data from Experiment : In this video I’m recording the Lightboard and switching between camera views and collecting live data through the Pasco system.
Lightboard And Using Prezi Instead of PowerPoint : In this video I’m recording the Lightboard and using Prezi (Prezi.com) instead of PowerPoint to present the material.
Lightboard And Using Prezi - How To Create a Prezi for the Lightboard : In this video I show how to create a Lightboard compatible Prezi file to present the material.
Why is it useful to be able to record a second computer in addition to the Lightboard? Basically it makes additional teaching options available to the instructors and it can save a very significant amount of faculty time that would otherwise be needed to edit instructional materials to be used with the Lightboard. Using computer graphics like Powerpoint slides with the Lightboard requires those slides to be in a very specific format. The slides must be in a 16 by 9 format with a black background and the slide must contain space within the slide for the instructor to be viewed “through” the slide. The text in the slides also needs to be of sufficient type size, like 24 font or greater, to be easily seen in the final video if viewed on a smaller screen like a laptop or tablet. In other words, instructors need to build a completely new set of lecture slides specifically designed to work with the Lightboard and that requires a lot of editing time for the faculty. Under my design, instructors only need to edit the slides they specifically want to use with the Lightboard. The rest of their slides that they don’t need to interact with through the Lightboard can be recorded separately and therefore will not need to be edited. An example set of Powerpoint slides designed to be used with the Lightboard can be found here.
Additional extensions that this system has include the following; shoots video at 1080 Progressive 60Hz vs 1080 Interlaced at 60Hz as found in the original design, the ability to record both H.264 (MP4) compressed video and completely RAW video for very accurate editing if desired, and finally this system is fully capable of recording RAW video at resolutions all the way up to 4K (4 times HD quality). Plus, the main Panasonic GH4 DSLR camera with its 14-140mm lens can be used as a standard DSLR for photographing departmental events if desired. Control of the video switcher camera views and media players can also be accomplished by the instructor directly at the Lightboard through an app called Strata-Lite (or Strata-Pro) running on an iPad mini mounted to the Lightboard. The Lightboard is also capable of “live streaming” video online if desired for online class office hours, reviews or research talks.
The room where this studio is built is 18 feet wide by 39 feet long……however, the Lightboard is setup across the width of the room and takes up a space of about 18 ft by 16 ft for the board and the lights. The camera is about 14 ft from the glass “board” and the board is about 4 ft from the black curtained wall. The computer station takes up about another 6-8 ft of the length of the room for an overall size of about 18 ft wide by 24 ft long for the Lightboard Studio itself. The rest of the room is an open space of about 18 ft by 15 ft that is used for the experiment/demonstrations area.
This is an overall view of the Lightboard studio using the bolted together frame purchased from Kevin Koch as listed on Dr. Peshkin’s “Parts” page. The frame has the additional “fancy” wheels added which allows us to easily move the frame or extend the foot to lock the board in position. The 80/20 aluminum framing has been added all the way around the frame and includes LED lights surrounding the entire glass sheet. The top and bottom frames have the brighter industrial LED lights mounted inside them and the side frames have the much cheaper Amazon Hitlights mounted inside them. Since the frame surrounds the entire piece of glass it’s self-supporting and does not require any clamps or other supports. The lights are the same grow lights used by Dr. Peshkin but have been mounted on frames with wheels for easy adjustment. The fact the lights and frame are both on wheels also makes this studio easier to move into a new space in the future if the needs arises. The wall behind the Lightboard has moving blankets mounted to the wall for sound absorption and then has a top layer of black muslin cloth. The room also has a layer of carpet for sound absorption to reduce the “cave-like” echo that can occur in enclosed studios.
Mounted to the bottom 80/20 frame is a piece of wood molding that acts as a marker tray with a second piece of molding for an edge to keep the markers from rolling off. The marker tray is mounted with 80/20 flat rectangular plates as you can see in the picture above. There is also a small bead of clear silicone caulk surrounding the edge between the glass and the 80/20 to waterproof the seam to protect the LED’s. Duke University did some experimenting with cleaning the glass and according to their tests a mixture of 1/3 Dawn dish washing soap and 2/3 water in a spray bottle worked best at cleaning the glass…..I’ve tried it and I’m not convinced yet.
In this photo and the next photo you can see the aluminum foil lining the ceiling in front of the back lights to help direct light downwards along with the black cloth hanging from the ceiling that prevents light from the backlights from directly being seen by the GH4 camera.
In the next two photos you can see the recording and editing station for the studio with Dr. Darin Acosta running the system. There are a total of three computers in the system. One “Master Computer” runs the video switcher and records the Lightboard alone in both H.264 or RAW video formats. The second computer, the Lightboard Feed Computer, feeds computer graphics (Powerpoint) into the video switcher for the Lightboard to use. The third “Mediasite Computer” is the instructor’s computer when they use the Mediasite system and record a simultaneous screencast from this computer along with the Lightboard. The Mediasite recording is currently being done by this computer using the Mediasite Desktop Recorder Version 2 software. However, for better recording quality using a Mediasite dedicated recorder could also be used but these boxes are quite expensive.
Here is a view of the backside of the recording station relative to the Lightboard.
More views of the recording station.
This is the instructors view through the Lightboard towards the 55 inch Sharp LED TV’s. The left TV acts as a teleprompter when using PowerPoints’ “Notes” feature attached to the instructors slides while in presentation mode. The right TV shows the final video that is being recorded which includes the instructor plus the video switcher merged Powerpoint from the Lightboard Feed Computer.
This is a front view of the main Panasonic GH4 camera which can shoot video and still images all the way to 4K resolutions and the two 55 inch Sharp televisions for feedback and teleprompting of the instructors. Notice the right TV includes the merged video image of the camera view (me with my camera) and the computer graphics being feed into the system from the Lightboard Feed Computer. The final video that is seen in the right TV is delayed slightly due to the signal being processed and you can graphically see that in this photo….notice that the left TV has a bright flash in the upper left corner from my camera flash but the right TV shows me and my camera without the flash on the camera firing! Pretty cool, actually!
This is a front face view of the camera and the mirror as it faces the Lightboard. Notice the front surfaced mirror is held to the mount with plastic mirror clamps to prevent damage to the front surfaced mirror. You can also see the linear polarizer mounted to the camera to cancel out the reflections from the TV’s in the glass of the Lightboard.
Here you can see the camera mounted to its expansion interface unit and what the camera sees through the mirror.
In this photo you can see a side view of the mirror mount, the camera ballhead and the Blackmagic HDMI to 4K SDI converter that takes the full sized HDMI cable out from the camera interface and converts the signal to a single 6G speed SDI cable to transfer the signal over long distances to the video switcher. Notice there is an additional unused SDI port for expansion if desired. The GH4 camera is mounted to the Panasonic Interface Unit and that gives me the option to take the camera off the base and use it as a portable studio quality camera with two XLR microphone inputs. The interface unit also has 4 SDI video outputs of its own that are capable of outputting four signals at 1080P 30Hz. While the interface unit is not necessary it does provide these nice benefits plus I was able to get it at a REALLY good educational price so I figured it was worth it.
Here you can clearly see the corner brackets used on the 80/20 framing to hold the frame together and the power supplies for the LED lights surrounding the glass mounted to the frame.
The bright industrial LED strips need to have a heat sink. After looking carefully at the 80/20 aluminum extrusion we noticed there is a tiny depression in the center that prevents good thermal contact between the LED’s and the 80/20. We decided to fill that tiny depression with thermal paste (like you would use between a CPU and a heat sink fan on a computer). Next we mounted the Kapton tape to a 1/2 inch wide aluminum strip and then mounted the LED’s to the Kapton tape. Finally we pressed the aluminum strip with the LED’s mounted on it into the thermal paste to create a good thermal contact that effectively transfers the heat from the LED’s into the 80/20 frame.
The additional channels in the 80/20 were good for cleanly running the wiring all the way around the Lightboard.
A close up view of the wheels on the Lightboard frame, by turning the orange disc you can raise and lower a rubber foot to take the pressure off the wheel and keep the board in a fixed position.
In this photo you can see the instructor’s Mediasite computer with the Smart Podium Monitor mounted on a shelf attached to a height adjustable arm that is attached to the Lightboard frame. You can also see the iPad mini in its mount with the Strata-Lite App running for wireless control of the video switcher and its camera views. In addition you can see the electronic pen has been used to write on the computer screen and that writing is captured “live” by Mediasite. Behind the monitor you can see the second camera, a Canon Camcorder, mounted on a ballhead that provides a headshot view of the instructor while they are writing on the monitor. This camera is mounted to a photographic “light stand” tripod that makes it height adjustable as well to accommodate different height instructors. A light stand tripod is used because it’s taller than a standard camera tripod.
Here is a close up view of the Smart Podium Monitor and electronic pen that you use to write on the screen, the five silver buttons across the top are four pen colors and one eraser.
The Inogeni HDMI to USB 3.0 converter takes the final video output from the video switcher and converts the signal into a “standard webcam” so that a wide variety of software can understand the video signal. It even uses the standard Windows webcam driver so no special driver is needed. The Mediasite software (or any other program that requires a webcam for video input like Skype for example) can understand and use the signal from the Inogeni for recording through the Mediasite Desktop Recorder Version 2.
This is a close up view of the iPad mini in its custom made security mount and the Strata-Lite App. Notice that I have limited the number of buttons showing on the app to only those items that are currently being used on the video switcher. In my case I have the “Comp” button for the feed computer, the “Head” button for the headshot view from the Canon camera, and the “Glas” button for the Lightboard view from the Panasonic GH4 camera. Note that once the video switcher is set up for a particular task, the only button the instructor needs to press is the “Auto” button to switch between camera views so it’s very simple for the instructor to operate while recording a lecture.
Here is a backside view of the custom iPad mount Ed Storch in the Physics machine shop built.
More views of the mounts holding the second camera, monitor and the iPad.
Notice the heavy weight hanging from the light stand tripod base to keep the camera’s center of gravity low and more stable.
The mounting arm holding the Smart Podium Monitor was a surplus adjustable arm from the physics machine shop that was designed to hold a computer interface for a milling machine. The nice thing about the arm is it’s designed to be used horizontally and its height adjustable while keeping the attached shelf and monitor level. With the Canon Camcorder on a ballhead attached to a light stand tripod and the adjustable monitor arm I can accommodate instructors of various heights easily with a few minor adjustments.
Here you can see the four monitors that operate the studio. Starting from the left side…monitor one is the primary screen monitor from the Lightboard Feed Computer that will display the notes from Powerpoint when in presenters’ mode. This is the same thing as displayed on the left Sharp 55 inch TV. The second monitor is the extended screen from the feed computer and where the Powerpoint gets fed into the video switcher. The third screen is the Master computer screen running the full Blackmagic ATEM software package that operates the video switcher. The Master computer is also used for recording the H.264 video from the Lightboard through the Blackmagic H.264 external recorder if you are making a Lightboard alone video. In addition, this computer can also record RAW video in both 1080P 60Hz and 4K P 30 Hz through a Blackmagic Decklink PCI 4K video capture card. The monitor on the far right shows the Multiview output from the video switcher showing all the video inputs on one screen at the same time. To the left of all the monitors you see the main equipment rack.
Close up views of the Lightboard Feed Computer monitors.
Close up views of the Master Computer monitor and the Multiview monitor from the video switcher.
This image shows the back of the Master Computer and the red 6G SDI cable feeding video into the Blackmagic Decklink 4K PCI video capture card from the SDI program output of the video switcher. The master computer was hand built to be sure that the components were compatible with the requirements of the Decklink card. The case is an Antec P100 and it contains an Asus Z-87 Pro motherboard, a 1TB WD Blue boot drive, a 3TB WD Black drive divided into a 1TB partition for boot drive backup and a 2TB partition for the main video storage space, and finally two Samsung 840 EVO 500Gb solid state drives in RAID 0 striped mode to handle the data flow from the Decklink card. When recording 1080P 60Hz RAW video its throwing something like 335 MB/s at the SSD drives and 4K throws 663 MB/s…both of which are faster than a single standard hard drive can handle but two SSD drives in RAID 0 can handle that data rate. At 4K those SSD drives allow about 20-22 minutes of raw 4K video to be recorded before it has to be stopped and the file transferred to another hard drive. The computer had to be hand built because Blackmagic has several lists on their website under the “Support” section that shows computer hardware that is known to be compatible with their own hardware. While you could put the Decklink card in just about any machine and try it to see if it works, the safest route was to do the research and buy hardware that was known to be compatible.
This is a view of the newly updated equipment rack and starting from the bottom is a Tripp-Lite surge protector, then the Blackmagic ATEM Production Studio 4K video switcher. Next is a 28 channel audio equalizer with low and high pass filters that allows me to manually isolate and remove some air conditioning rumble noise from the room AC vent. Above that sits two Behringer FBQ100 devices (one for each channel of audio) that have built in adjustable digital delay, a noise gate and a compressor. A noise gate is exactly like what it sounds like….it’s an adjustable dB level that can be used to reduce background noise below the level you set. A compressor allows the audio to be leveled out or compressed to an adjustable range so that sounds that are too high or too low in volume can be reduced or enhanced to stay with the acceptable range. The audio processors allow me to add a delay to the audio to get it in sync with the video during recording without having to post-process the video. Video is more data intensive than audio and takes longer to get through all the electronics so it arrives slower and out of sync with the audio. Adding a delay allows the audio to be slowed so it’s back in sync with the video without post-processing the video. The delay in my setup turns out to be about 108 milliseconds. I measured it by creating a circuit with a light and a bell….by turning on the circuit it would activate both the light and bell. I then filmed it and using Adobe Premiere I analyzed the final video to see when the light came on and measured the time difference from when the audio track started (good idea, eh?). Next we have two Telex FMR-500 wireless microphone receivers and finally a Mackie audio mixer. I chose the ATEM 4K Production Studio over the Television Studio used by Dr. Peshkin because it can handle a much wider variety of resolutions and was only a little more expensive. As for the microphones, equalizer, surge protector and the Smart Podium Monitor, I happened to have all of those items left over in surplus from a recent renovation of the A/V systems in my physics auditoriums so I didn’t need to purchase them. The audio mixer was donated by one of the Physics staff members, Pete Axson, from his personal property. As for the equipment rack itself, it was custom built by Ed Storch in the Physics machine shop from some recovered parts that I once again had in surplus.
This is the Behringer Shark FBQ100 showing a 108 millisecond delay on the display.
The picture above is a back view of the wiring in the equipment rack (this is an old view showing an old Sabine product that was replaced by the Behringers).
Here you can see the three HDMI video splitters that run the system. These splitters are Kanex Pro splitters with EDID control. EDID stands for Electronic Display Information Data and that basically means it detects and remembers the capabilities of all the HDMI equipment and makes sure the “handshake” between them goes smoothly. Without EDID control I would often lose the picture on one of the televisions and would have to pull and reset HDMI cables to fix the issue. In short, GET EDID splitters. The Lightboard Feed Computer has a video card with two video outputs to drive two monitors. I take each output and run it into an HDMI 1x2 splitter. For the primary display from the computer I run the outputs to the local monitor and also to the left Sharp 55 inch TV so instructors can see their notes as a teleprompter. The extended display of the Lightboard Feed Computer with the Powerpoint slides themselves also gets split with a 1x2 where one output goes to the video switcher to feed it signal and the other output goes to a local monitor for monitoring the signal. The video switcher is quite sensitive to signal strength so I occasionally need to unplug and reset this “feed” HDMI cable to get the switcher to “see” the signal again if it drops it. The 1x4 HDMI splitter takes the final video program output from the video switcher and splits it into four outputs. One output feeds the H.264 recorder on the Master Computer for recording, another output feeds the Inogeni Webcam converter for Mediasite Recording, the next output feeds the right Sharp 55 inch TV for the instructors to see themselves in the final video and can use it for feedback when drawing on computer graphics, and finally the last output feeds an HDMI to RCA audio extractor. Shown in the picture below is the audio extractor (converter) is used so I can monitor the final audio output of the video switcher with a set of headphones “live” during recordings. The audio from the extractor feeds a small headset amplifier that in turn powers a headset. The HDMI cables I am using are Bluerigger cables that I purchased from Amazon and they have all worked great.
The Pyle headset amplifier supports up to four headsets at once……but I’m only using one output.
This is a back view of the recording station and its wiring.
This view shows the new experiment/demonstrations area with the Pasco system and a third camera on a tripod. The monitor, keyboard, mouse and Pasco system are all connected to the Mediasite Computer (the same computer that runs the Smart Podium Monitor that is attached to the Lightboard). A single computer can not only have dual mirrored monitors but can also be controlled with dual keyboards and mice. I am able to make this extension by using a powered USB 3.0 extension cable and powered USB3.0 hub to run the components. Shown below is a closeup view of the setup with the Pasco software running on the monitor. The Pasco interface has ports for attaching multiple sensors of various types at the same time.
Notice there is a gap between the wall and the control table so the instructor can walk smoothly and quickly from behind the Lightboard to the experiment area. That means the instructor can control the whole setup through the iPad Strata-Lite app and make camera changes themselves without the need for an operator even if they are using all three camera views (Lightboard view, Headshot view, and Experiment view).
Here we have a small equipment rack Ed Storch built to hold two more power surge protectors (one of which I also had in surplus). J I’m quite the scrounger for parts!!! J
This is a control box that sits next to the Master Recording Computer that users use to turn the entire Lightboard system on with this one switch by controlling a 4 channel solid state relay circuit board. The first picture below shows the electrical junction box where the relay is located in the ceiling above the Lightboard. A single contact closure control wire runs from the “bomber” switch up to the relays and the relays just detect when this switch is closed and that signal turns on the relays. Three of the relays operate the three separate electrical circuits that power the Lightboard. The fourth relay powers up the active cooling fan mounted into the junction box that blows air across the relay circuit board. Why? Well the solid state relays are rated to 25 Amps but upon reading the fine print it turns out they can only handle 10 Amps unless they have active cooling. I burned up one relay before discovering that fine print. With power load balancing, I am actually typically running less than 10 Amps on each of the three circuits powering the Lightboard system but as a safety precaution I went ahead and added the active cooling. Basically my machine shop guys cut a hole for the fan in the front of the junction box and cut some air exit holes in the back that are located underneath the relay circuit board (which is mounted on some standoffs inside the junction box).
The red “bomber” switch is actually a double throw switch (two switches) and the second part of it activates a red studio light to indicate when the room is occupied and making recordings. By flipping the red “bomber” switch it turns on the red light outside of the room so visitors know the room is in use. Visitors outside the room can also indicate to the user inside the room that they are there and waiting for room access by pushing a switch that activates a yellow light. Both the red and yellow lights are seen by the person inside and the person outside so they both have visual feedback. The wall panel located outside of the room is seen in the picture below.
Since the system was built originally, I’ve also added a set of wireless headphones on the audio out from the Mediasite computer that allows us to conduct live office hours using the Lightboard through programs like Skype, Youtube or Big Blue Button which is built into the Canvas LMS teaching system we use on campus. I’ve also added a shelf attached to the Lightboard which holds a Monarch HD recording and live streaming device. The Monarch allows simultaneous live streaming and recording to a multitude of websites like YouTube.
Well, that’s the system! If you read this far I hope you liked it. Feel free to contact me if you have any questions (mocko “at” phys.ufl.edu or 352-392-0488).
Senior Teaching Laboratory Specialist (Physics Lecture Demonstrations)
Department of Physics
University of Florida