Touchscreen Progress 3
I sanded flat my LED's yesterday - hopefully my UV glue will arrive today or tomorrow so I can get them attached. I also ordered some aluminum extrusions to use for framing the screen (off ebay - there is an ebay store that sells small quantities and will cut them to size for you). I also got a 'first hack' of the blob tracking software working. I will work on improving it incrementally. I also may end up writing my own blob detection code too since the CV blobs lib is returning some strange results at times and it shouldn't be a very hard algorithm at all given the data (just a connected components algorithm).
5 Comments:
I'm not finding much difference between glued and non-glued LEDs. I'll be interested to hear about your experience with the UV glue.
Re the software, you might consider this library which is a public-domain implementation of the KLT tracking algorithm. I used it successfully a few years ago (albeit not in a real-time system). And I notice that Jeff Han has previously written a GPU version of the KLT algorithm that he said yielded a 5x speed-up.
Alternatively, "connected components" seems pretty straight-forward.
Finally, it struck me that for some applications you wouldn't even need to do object identification and tracking. Imagine, for example, a LavaLamp-like interactive simulation/artwork. Here you could just repell globules away from white (FTIR) pixels. Or even use openCV's optical flow call to generate a deforming vector field.
hehe, I wish you had posted that before i sanded most of my LED's. I'm finding the UV glue to be a little bit of a pain in the ass since I don't have a UV lamp. I'm gonna try leaving it in the sun to cure next time there is a bright sunny day. What did you use to cure it?
Thanks for the tip about the library. I will check it out.
That is true about the optical flow being good for some applications. For basic GUI based apps you're going to want to have the events rather than having to do image analysis, so having both might be cool.
BTW, do you have a UV lamp or did you just put it outside? I assume a regular blacklight is not the proper spectrum nor intense enough to have any effect, right?
I think sanding the LEDs flat is still a good idea - if only for the hynotic trance it induces ;-)
Re the lamp, our office happens to be across the hall from a glass studio. They've got the UV glue (Loktite brand) plus an 8W lamp. Even with this though, I found it took 5 minutes to cure. Searching around on the net, I came across a recommendation for Norland glue. Contacting the company, they suggest this product. We might go with this for our next prototype.
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