OFFICIAL Multitouch FAQ - Frequently Asked Questions Thread
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Example Reply to this post:
Q 2) What are the possible ways of making a multitouch device?
a. There are many ways to create multitouch devices. To find the four main do-it-yourself techniques (FTIR, DI, LLP, DSI) used on the forum, please see “Getting Started With Multitouch” here: http://nuigroup.com/forums/viewthread/1982/
Q 1) What is multitouch?
a. Even if the prefix MULTI stands for 2 or more, multitouch technology often refers to a screen that allow users to interact with a computer system with N number of fingers, therefore allowing for multiple object manipulation, gestures and multiple users interaction. - lolec
Q 2) What are the possible ways of making a multitouch device?
a.
Q 3) What is a “compliant surface” and why do/don’t I need one?
a. The compliant surface or compliant layer is simply an additional layer between your projection surface and your acrylic. It enhances the finger contact and gives you more robust blobs, particularly when dragging as your finger will have less adhesion to the surface then.
It is only of any use in FTIR displays, if you are building DI, LLP, or other methods, you will not use a compliant layer. If you are building FTIR, a good compliant layer is the difference between a display that works...mostly, and a consistent force display. There is much experimentation ongoing in the quest for the ‘perfect compliant layer’.
Some materials used to success include SortaClear40 and similar catalyzed silicon rubbers, Lexel, and various brands of RTV silicone. Others have used fabric based solutions like silicon impregnated interfacing and SulkySolvy.
The original successful method, still rather popular, is to ‘cast’ a smooth surface directly on top of your acrylic and then lay your projection surface on that after it cures. This requires a material that closely approximates the optical properties of the acrylic as it will then BE a part of the acrylic as far as your transmitted IR is concerned, hence the three ‘rubber’ materials mentioned earlier...they all have a refractive index that is very close to that of acrylic.
Gaining in popularity is the ‘Cast Texture’ method. Tinkerman has been leading the pack in making this a simple process for DIY rather than an involved commercial process. But essentially, by applying your compliant layer to the underside of your projection surface, and texturing it, then laying the result on your acrylic, you gain several benefits. Your compliant surface is no longer a part of the acrylic TIR effect so you are no longer limited to materials with a similar refractive index to that of acrylic, although RTV and Lexel remain the most popular choices, edging out catalyzed silicons here. Since it is largely suspended over the acrylic by the texture, except where you touch it, you get less attenuation of your refracted IR light (brighter blobs).
Fabric based solutions have a smaller following here, and less dramatic of a proven success rate, but are without question the easiest to implement if an appropriate material can be sourced. Basically they involve lining the edges of your acrylic with two sided tape, and stretching the fabric over it, then repeating the process to attach your display surface. - Trackzilla
Q 4) Where can I buy silicone rubber sheets or liquid silicone for pouring my own?
a.
Q 5) What is the best multitouch technique?
a.
Q 6) Do I have to use a projector?
a.
Q 7) What projectors are best?
a.
Q 8) What kind of LEDs are best and where can I buy them?
a.
Q 9) What is IR (infrared) and why is it needed?
a.
Q 10) Do you have to use IR LEDs?
a.
Q 11) How do I wire my IR LEDs?
a.
Q 12) What does diffusion mean and what is a diffused surface or diffusor?
a.
Q 13) What kind of light illuminator is best and where can I buy one?
a.
Q 14) What type of projection surface is best?
a.
Q 15) My projector doesn’t produce a big enough image, what do I do?
a.
Q 16) What do I need to create a FTIR table?
a.
Q 17) What do I need to create a front/rear DI table?
a.
Q 18) What do I need to create a LLP table?
a.
Q 19) What do I need to create a DSI table?
a.
Q 20) What are the possible different tracking software currently available?
a.
Q 21) What tracking software is best?
a.
Q 22) What programming is the best to develop in?
a.
Q 23) What language is best to develop multitouch applications?
a.
Q 24) Where can I find multitouch applications?
a.
Q 25) What is the cheapest and quickest way to make a multitouch input device?
a.
Q 26) Are there test videos I can use since I don’t have a multitouch table yet?
a.
Q 27) How can I start making applications without a multitouch device?
a.
