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POCoordinate Transformation C++
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  1. POCoordinate Transformation C++
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    copied!<p>I have a webcam pointed at a table at a slant and with it I track markers. I have a transformationMatrix in OpenSceneGraph and its translation part contains the relative coordinates from the tracked Object to the Camera. Because the Camera is pointed at a slant, when I move the marker across the table the Y and Z axis is updated, although all I want to be updated is the Z axis, because the height of the marker doesnt change only its distance to the camera. This has the effect when when project a model on the marker in OpenSceneGraph, the model is slightly off and when I move the marker arround the Y and Z values are updated incorrectly.</p> <p>So my guess is I need a Transformation Matrix with which I multiply each point so that I have a new coordinate System which lies orthogonal on the table surface. Something like this: A * v1 = v2 v1 being the camera Coordinates and v2 being my "table Coordinates" So what I did now was chose 4 points to "calibrate" my system. So I placed the marker at the top left corner of the Screen and defined v1 as the current camera coordinates and v2 as (0,0,0) and I did that for 4 different points. And then taking the linear equations I get from having an unknown Matrix and two known vectors I solved the matrix.</p> <p>I thought the values I would get for the matrix would be the values I needed to multiply the camera Coordinates with so the model would updated correctly on the marker. But when I multiply the known Camera Coordinates I gathered before with the matrix I didnt get anything close to what my "table coordinates" were suposed to be.</p> <p>Is my aproach completely wrong, did I just mess something up in the equations? (solved with the help of wolframalpha.com) Is there an easier or better way of doing this? Any help would be greatly appreciated, as I am kind of lost and under some time pressure :-/ Thanks, David</p>
 

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