Still messing with qtrack

Ok, boring things first. I uploaded another qtrack version with some minor fixes and improvements, and also added broomstick example there. Nothing groundbreaking so far.

Now, to fun things. I tried to make non-square marker qtrack mod based on this method. You can see in this video how far I could push it:

but, overall, this was a failure. Unlike that guy, I had only one shape to detect, so at 1st I thought I could use max ICF value between blob and marker contours (ideally 1) and compare it to confidence threshold. However, this picked way too much false positives. So in 2nd iteration, that you see in the video, I had to calculate max ICF values for few hundred blobs 1st, and then pick the blob with max of those values. This worked somewhat better, but in the long run, it is still unreliable. Here is a distribution of max max ICF values thresholded at 0.7:

As you see, even shape as simple as flash logo produces really poor values most of the time. Another equally significant problem is that BitmapData’s threshold() method produces poor contours when threshold is not optimal: over-illuminated patches of the marker punch random ”holes” in its binarized version and contaminate detected contour. To sum up, you will have to stick with quad markers for some time, sorry.

Meet qtrack

It stands for “quadrilateral tracker”, little pet project I have been sporadically working on since october. I should have given it more love, but I didn’t want this post to drag into next year, so here goes “version 0.9″:

After December 7th, qtrack is the only free, as in “free beer”, flash 3D AR tracker. Curious why? There are many reasons for that. For one, most of its code is already available for free elsewhere on the web. But another, more important reason is that I just don’t see enough flash AR around, and setting this thing free is my modest contribution to spark some more creativity in the field :) I mean, when was the last time you actually saw flash AR game, huh?..

Any way, back to qtrack – it works similarly to famous FLARToolKit, except it is not that advanced and currently implements only single instance of single quad marker tracking. On the bright side, it is less restrictive regarding marker shape – all these markers could be tracked with qtrack, for example:

So, this is something you can try today. Zip file comes with two simple examples for Away Lite and Alternativa engines, and soon short video tutorial will follow. In January I will try to further improve qtrack in the areas where it currently have problems, and release stable version 1.0.

Credits

As I said, most of this thing is based on free code snippets published or inspired by various people. This includes blob detection (Tomek), homography (Zeh), marching squares (Sakri), Otsu thresholding (Andrew), automatic thresholding (some unknown guy), brilliant camera activity trick (Deepanjan). Even my complex numbers experiment found its way into this – I used it for pose estimation. So big thanks goes to all these people who have posted right things at right time for me to come across – without you qtrack would never happen!

Midnight Brainfuck

Did you ever tried to imagine what would rotation of impossible rectangle look like? Well, these guys did but, with all due respect, their results are ugly. I thought I could do better than that, so tonight I made this:

(click it to go to my wonderfl code)

Spherize filter

Last night I was thinking of ways to create “fish eye” effect with flash 3D engines, and decided that Pixel Bender is the way to go. However, two things I’ve found on the internet did not make it look the way I wanted, so I ended up creating my own “spherize” filter:

Of course, it is not limited to 3D – you are free to use it in any other way, too.

Animated 3D Pythagoras tree

This is (re)animation of last year experiment that I have been playing with over the holidays. Now you can see great diversity of this fractal in real time: