How a marker-based augmented reality algorithm (like ARToolkit's one) works?

From scratch' is a relative term. Truly doing it from scratch, without using any pre-existing vision code, would be very painful and you wouldn't do a better job of it than the entire computer vision community.

From scratch' is a relative term. Truly doing it from scratch, without using any pre-existing vision code, would be very painful and you wouldn't do a better job of it than the entire computer vision community. However, if you want to do AR with existing vision code, this is more reasonable.

The essential sub-tasks are: Find the markers in your image or video. Make sure they are the ones you want. Figure out how they are oriented relative to the camera.

The first task is keypoint localization. Techniques for this include SIFT keypoint detection, the Harris corner detector, and others. Some of these have open source implementations - I think OpenCV has the Harris corner detector in the function GoodFeaturesToTrack.

The second task is making region descriptors. Techniques for this include SIFT descriptors, HOG descriptors, and many many others. There should be an open-source implementation of one of these somewhere.

The third task is also done by keypoint localizers. Ideally you want an affine transformation, since this will tell you how the marker is sitting in 3-space. The Harris affine detector should work for this.

For more details go here: http://en.wikipedia.org/wiki/Harris_affine_region_detector.

1 Thanks for the references. I'm not looking to do a better work than the entire computer vision community, i'm just looking to implement the subset required for the particular task of finding the markers :-). However what I need to know is how every part works, from the step of having a bitmap with the frame to the construction of the transformation matrix used to place 3D objects.In detail :-) Basically: 1.

Get the image from the camera 2. Convert it to RGB or some other processable format 3.? N. Use the transformation matrix.

I need to know exactly the steps 3..N-1 :-) – Bad Sector Feb 12 '10 at 15:09 I suggest buying the O'Reilly OpenCV book. – forefinger Feb 12 '10 at 17:30 does it explain the algorithms or just the API? – Bad Sector Feb 22 '10 at 11:11 It explains both.

– forefinger Feb 28 '10 at 22:48.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.