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In OpenCV, we can use a xml file to describe haar-like features of a specific object. I wanna use this idea to detect palm and fist, now I hava my own xml feature file, and it works well in C and Python(with OpenCV), now I need to move this idea to flash.

Luckily, I found an project named Marilena, it successfully moved the haar-trainning part of OpenCV to actionscript, and this article optimizing flash based face detection optimized Marilena, he turned the xml file into actionscript class itself to speedup the calculation. However, since the Haar data is being hardcoded into the class now it will not be able to use for tracking anything else but faces. I try to read the source code for detail, and process my own xml file into actionscript class file in his way, but finally find something different.

The xml file for face detection is like :

enter image description here

Every tree has only one node "root node", but in my xml file, some trees have two nodes, and the "left_val" above changes to "left_node" sometime, I don't know how to process these nodes. I think I should goto OpenCV C source files for detail to find how to correctly process xml feature file, but where to start, some advices?

Kumsal Obuz
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PinkyJie
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1 Answers1

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I'd suggest reading on E4X in Actionscript and binary trees for algorithm purposes.

So, if you can distinguish left_val and left_nodes which seem like branches (nodes in your cases) and leaves when you are parsing your xml data, you're on the right path. As you can guess, when a leaf is a node, that will branch into more leaves so basically everything is leaves but can have special meaning like holding/giving access to more leaves. I'm sure the article will make more sense but I just wanted to summarize it.

You might also want to take a look at recursive functions because you may need a self looping function to run through the leaves. Here is the wiki for that : http://en.wikipedia.org/wiki/Recursion_(computer_science) Fibonacci numbers is a good example for this and you can also find binary search in the same article which will hopefully be all you need.

Have fun.

Kumsal Obuz
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  • Thank you, @kubarium, but that is not the point. I know the principle of binary tree and recursive function, and I can successfully process my xml file, what I really need to know is how haar-like detector use the xml file to detect object, I wanna know which files in opencv should I go through. – PinkyJie Nov 14 '11 at 09:12
  • I'm sorry. When you said you didn't know how to process those nodes, I thought it was more of a programming and algorithm issue. So, to paraphrase your comment,would it be right to say: You are not sure which node means what in that structure (xml example) you provided? In that case, I have no information on this topic but looking at the Marilena project files, I've found: http://www.libspark.org/browser/as3/Marilena/trunk/src/jp/maaash/ObjectDetection/HaarCascadeLoader.as?rev=567 which looked like the parser. I don't want to waste your time since I'm not so sure if I'm on the right page here. – Kumsal Obuz Nov 16 '11 at 15:38