ippiGetAffineTransform wont work

[micromysore]

I am not sure as to what am i missing here .. but any pointers will help ..

I am trying to get transform coeffs using ippiGetAffineTransform.

I supply the quad ..



[assume appropriate declarations have been made .. ]



IppiRect imgRect1 = { -IMAGE_WIDTH/2, -IMAGE_HEIGHT/2, IMAGE_WIDTH/2, IMAGE_HEIGHT/2 };

quad1[0][0] = imgRect1.x; // tl

quad1[0][1] = imgRect1.y;

quad1[1][0] = imgRect1.width; // tr

quad1[1][1] = imgRect1.y;

quad1[2][0] = imgRect1.x; // bl

quad1[2][1] = imgRect1.height;

quad1[3][0] = imgRect1.width; //br

quad1[3][1] = imgRect1.height;

for(i=0;i<4;i++)

{

quad[0] = coeffs1[0][0]*(quad1[0]) + coeffs1[0][1]*(quad1[1]);

quad[1] = coeffs1[1][0]*(quad1[0]) + coeffs1[1][1]*(quad1[1]);

}



stat = ippiGetAffineTransform(imgRect1, quad, coeffs);



now the coeffs doesnt have the coefficients (some junk values)..

ideally i wud expect the fn to load the coeffs with the same values as coeffs1 which was used to create the quad.



-madan

Message Edited by micromysore@yahoo.com on 03-07-2006 12:33 PM

[Vladimir_Dudnik]

Hi,

there is comment from our expert

IPP Geometrical functions work with convex (not concave) quadrilaterals only.

The parameter 'quad' whichyou pass to the ippiGetAffineTransform is non-convex. It seems that the mistake is at following lines

quad1[

2][0] = 0;//imgRect1.x; // bl (should be quad1[2][0]=imgRect1.width)
quad1[3][0] = imgRect1.width; //br (should be quad1[3][0] = 0)

Regards,
Vladimir