This is a long overdue post… The table has been functional for more than a year but we keep adding things to it so we never call it “final”
(Long post and lots of pictures)
Basic data about the project
Code Name: VISION DECK
Device type: Horizontal table
Display: Projector, Benq MP622c
Display area: 85cm x 65cm, 100cm+ diagonal, 4:3 format
Enclosure: 1m x 0.8m x 0.9m (w x l x h) box (Sorry jimihertz, we like rectangular boxes )
Construction material: Black, 1.8 cm thick particle board (chipboard) with plastic and metal insertions
IR source: 850nm LED ribbons, 2 sides
Sensing: Sony PS3 EYE
Filtering: 850DF10 bandpass filter on the camera + Hot mirror on projector
Cooling: Active, 4 Fans+airflow pipes, 2 Intakes, 2 Exhausts, Peltier Cooling
Computer: Custom made case, minimal hardware parts, Core2Duo 2.4 GHz, overclocked to 3 GHz, Nvidia 9400 GT
Rigid Surface: Acrylic 8mm thick
Compliant and Projection surface: refined Tinkerman’s technique + Vellum +semi-rigid transparent adhesive foil+ low-friction matte windows film
Optical path: Folded, 2 mirrors, 1 fixed, 1 adjustable in 3D
Mobility: 4 brake wheels + 4 adjustable height plastic feet
Power supply: 1 ATX power supply for the computer+fans+IR-Leds+Logo+Control Box Leds
Operating System: Windows XP
Tracking application: CCV
1. Computer controlled projector
Using the RS-232 connection provided by the projector an application has been implemented to start the projector when Windows starts. While the projector is warming up, the application disables windows keys and functions such as ctr-alt-del, alt-tab, the taskbar, the desktop icons, systray etc and modifies the start menu to show only multitouch apps. CCV is started, b is pressed after 5 seconds (useful in the days of tbeta), flosc and then a flash app (would need a flash app loader). By the time the projector is on, the user sees only multitouch content. When the app senses a windows shut down it powers off the projector and waits until the lamp is cooled to allow the internal box fans to remain powered (Same power supply for all, when the system stops, fans cease to operate). The app was developed in Delphi and it’s very small.
2. Rear illuminated Logo
The Vision Deck logo has been made from a clear Plexiglas piece and several layers of plotted film have been added to it to form the logo where the letters V, D and the vision deck text are covered in matte film. Using 4 white LEDs placed on the side of the logo when the system is on the logo is lighted.
3. Control Box
Under the logo a small circuit has been made to start and stop the system and to control power to the IR LEDs and Fans. It also houses the remote of the projector in case it’s needed for image adjustments (although the control application can perform these tasks) The logo module has a push-lock switch and can be rotated so that it exposes the control box, effectively hiding it and preventing accidental tampering. 3 red Leds show the current state of the system (power, IR, fans)
4. Drag-release retractable power cord
(Vacuum cleaner technology ) the cable can be retracted under the table for fast deployment or extended up to 6 m.
5. Invisible ventilation
All the fans are on the bottom of the box and airflow is directed through aluminum pipes for cooling the projector and the computer. Under the table each fan takes/releases air from/to the environment in a different direction so the hot air is not recycled underneath the box. This system keeps the overall temperature inside the table below 30 degrees and the projector and video card at max 43 degrees as shown in a thermal vision photo of the box later in this post.
6. Modular design
All components can be removed easily. The top frame (containing the acrylic and leds) can be detached and it is locked into place with 4 blocking devices used in the furniture industry. The same blocks are used to lock the retractable power cord mechanism, the power connectors and the mirrors. The projector’s height, orientation and angle can be changed using another type of furniture metal support, the one used for hanging lockers etc. on the wall and the whole projector system can move on a rail for adjusting the display area.
7. Dirt and scratch-proof compliant and projection surface.
Vellum is rather good as a projection surface and silicon can be rolled to it providing nice blobs. The biggest problem is that it wrinkles; it is susceptible to water damage and gets very dirty in no-time. The laminating process can help but laminating foils are usually rigid and have a lot of friction. We have chosen 2 additional layers of adhesive films on top of the vellum, The first one is a semi-rigid plastic material and the second is a thin low friction matte film. The combination of these 2 materials hardens the vellum, still allows for great blobs and protects it from environmental damage. The matte foil also helps with projection since it reduces the “washed color” effect of the vellum. Since these are self -adhesive foils the surface can be glued to the acrylic under the aluminum rails housing the Leds, preventing the displacement of the foils in time. The last surface is also very friendly to touch and drag operations are smooth.
8. Custom made computer case
There was not enough space to put the whole computer inside the table (projector path occlusion). We built a wood support for the motherboard, the HDD and the power supply. This reduces heat accumulation, takes up a small space and no other power hungry components such as dvd-roms or additional case fans are needed. The “case” has shock absorbents, as many of the other vibration-prone components (the mirrors, the projector etc.). A wireless network card was installed so the table has internet access. In case of maintenance or debugging a wireless keyboard and mouse are also available.
Problems and observations
A large and tall box is subject to a lot of vibration. We have hardened the edges with L-shaped profiles to reduce this effect, but it’s still present when a strong touch occurs. Due to the thickness of the acrylic (8mm) and the large display area, sagging could have been a problem but the acrylic is sandwiched and has an 8cm base on all sides therefore it does not bend under normal pressure.
Brake wheels are nice but they will not hold the table in place (because the wheel axis is not concentric with the wheel, the table can still spin around) thus the need for plastic feet when the table is on display.
Mirror alignment is probably the worst part. Working with large mirrors (2), a mm displacement on the first mirror can add up to 2 cm on the display. A lot of time has been spent on this.
We still don’t have FS mirrors, but by carefully aligning the mirrors the ghosting effect is visible but not bothering
We keep the tracking speed at 75fps. The system can handle more but at 75 the speed is good enough and the lower the fps the better the blob clarity since more light can be captured by the ps3 eye.
It’s heavy … even the box by itself needs some serious manpower when you have to move it up the stairs
We’re hardware maniacs so the software part is still in progress. We do have 1 medical application and 2 electrical engineering apps in the works.
We sincerely thank the NUI Group Community. This project could not have existed without the work of so many multitouch enthusiasts. We hope this contribution will help others in building their devices.
If anyone needs more information, photos or details regarding the building process or the materials feel free to ask
The VISION DECK team.
Pics to follow
The VISION DECK
Internal Components (still some wire management needed, but it will always be in beta stage )
Close-up of the components
VD in action
We have access to a high resolution thermal imager so we could analyze the heat dissipation with our ventilation system. The first pic shows the temperatures with the fans on. Top right the projector lamp, bottom left the video card
Second thermal vision photo is without the ventilation on. The temperatures go skyhigh at over 50 degrees (in only 10 minutes of testing)
And finally the design concept for the logo