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POHow to apply a transformation matrix?
 

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  1. POHow to apply a transformation matrix?
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    <p>I am trying to get the 2D screen coordinates of a point in 3D space, i.e. I know the location of the camera its pan, tilt and roll and I have the 3D x,y,z coordinates of a point I wish to project.</p> <p>I am having difficulty understanding transformation/projection matrices and I was hoping some intelligent people here could help me along ;)</p> <p>Here is my test code I have thrown together thus far:</p> <pre><code>public class TransformTest { public static void main(String[] args) { // set up a world point (Point to Project) double[] wp = {100, 100, 1}; // set up the projection centre (Camera Location) double[] pc = {90, 90, 1}; double roll = 0; double tilt = 0; double pan = 0; // translate the point vSub(wp, pc, wp); // create roll matrix double[][] rollMat = { {1, 0, 0}, {0, Math.cos(roll), -Math.sin(roll)}, {0, Math.sin(roll), Math.cos(roll)}, }; // create tilt matrix double[][] tiltMat = { {Math.cos(tilt), 0, Math.sin(tilt)}, {0, 1, 0}, {-Math.sin(tilt), 0, Math.cos(tilt)}, }; // create pan matrix double[][] panMat = { {Math.cos(pan), -Math.sin(pan), 0}, {Math.sin(pan), Math.cos(pan), 0}, {0, 0, 1}, }; // roll it mvMul(rollMat, wp, wp); // tilt it mvMul(tiltMat, wp, wp); // pan it mvMul(panMat, wp, wp); } public static void vAdd(double[] a, double[] b, double[] c) { for (int i=0; i&lt;a.length; i++) { c[i] = a[i] + b[i]; } } public static void vSub(double[] a, double[] b, double[] c) { for (int i=0; i&lt;a.length; i++) { c[i] = a[i] - b[i]; } } public static void mvMul(double[][] m, double[] v, double[] w) { // How to multiply matrices? } } </code></pre> <p>Basically, what I need is to get the 2D XY coordinates for a given screen where the 3D point intersects. I am not sure how to use the roll, tilt and pan matrices to transform the world point (wp).</p> <p>Any help with this is greatly appreciated!</p>
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    1. COIs this similar to what you're looking for? http://stackoverflow.com/questions/130829/3d-to-2d-projection-matrix
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    2. CONo that's not what i'm after, they already know the 2d screen coordinates, I am trying to find them. Also they do not know the camera location, I do.
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