What are UV coordinates?

Isn’t it amazing how many people in the field do not understand UV coordinates? I thought so too, so back in 2011 I took two images from Senocular article and made this animated GIF:

Well, I am just reposting it here now in case Alternativa3D wiki currently hosting it will go down, like their forum did.

Grab my balls

So, I have started cross-engine 3D primitives project at github. Just like as3dmod, it plugs seamlessly into your favorite engine to help you out whenever you feel limited by it. Initial commit supports Alternativa3D 8.12, Away3D 4 Alpha, Minko 1 and contains two spheric primitives: UniformSphere and Globe.

UniformSphere is a mesh built from the spiral of vertices uniformly distributed across the sphere. You have two options here: Rakhmanov formula (default, the spiral joins sphere poles) or Bauer formula (the spiral does not contain poles). This primitive was ported from my 3D metaballs code.

Globe is a mesh that minimizes texture distortions for classic plate carré projection. It does so by placing equilateral triangles along the equator and gradually compressing triangles towards each pole (where high triangle density is actually good property in terms of texture distortions). This primitive was ported from my globe component for FP9, which is now also hosted at github.

I plan to add few more primitives over time, both useful and not really, and maybe more engine proxies if there will be any interest.

Update on qtrack

For those of you who are still interested in my free marker-based flash AR tracker, I updated qtrack to v1.0. There were actually only few minor changes, however. 1st, I changed detector code to avoid v0.9 marching squares bug; interesting side effect of this change is that now literally anything that remotely resebles a quad can be used for the marker (like those examples on the right). 2nd, I added requested option to track the marker in NetStream-ed video. 3rd, there is new makePlaneTransform method that should help you with molehill setup (but no molehill demo included for now). 4th, some minor stuff you wouldn’t care about.

On a related note, back in December I promised to make Alternativa3D AR video tutorial for russian xmas, that would include qtrack and other trackers available through FLARManager. I did not finish that video in time, so for this post I uploaded qtrack part only (and chances are that FLARManager part will be only available in text version of tutorial). The video is in russian, but you can try english subtitles. Enjoy:

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)