Re: Find homography in D?
On Sunday, 21 April 2024 at 14:57:33 UTC, Paolo Invernizzi wrote: Hi, Someone can point me to a D implementation of the classical OpenCV find homography matrix? Thank you, Paolo Now, we can do image stitching using DCV. It needs improvements though. https://github.com/libmir/dcv/tree/master/examples/imagestitchinghomography
Re: Find homography in D?
On Sunday, 21 April 2024 at 14:57:33 UTC, Paolo Invernizzi wrote:
Hi,
Someone can point me to a D implementation of the classical
OpenCV find homography matrix?
Thank you,
Paolo
Something I wrote awhile ago...
```
import kaleidic.lubeck : svd;
import gfm.math;
import mir.ndslice : sliced;
auto generateTransformationArray(int[] p) {
return generateTransformationArray(p[0],p[1],p[2],p[3]);
}
auto generateTransformationArray(int x, int y, int x_, int y_) {
return [-x, -y, -1, 0, 0, 0, x*x_, y*x_, x_,
0, 0, 0, -x, -y, -1, x*y_, y*y_, y_];
}
auto transformCoor (mat3d mat, vec3d vec) {
auto res = mat * vec;
return res / res[2];
}
auto findHomography (int[][] correspondances) {
auto a = correspondances
.map!(a => a.generateTransformationArray)
.joiner
.array
.sliced(8,9);
auto r = a.svd;
auto homog = r.vt.back;
return mat3d(homog.map!(a => a/homog.back).array);
}
```
Re: Find homography in D?
On Sunday, 21 April 2024 at 14:57:33 UTC, Paolo Invernizzi wrote:
Hi,
Someone can point me to a D implementation of the classical
OpenCV find homography matrix?
Thank you,
Paolo
Just for future records in the forum.
//
https://math.stackexchange.com/questions/3509039/calculate-homography-with-and-without-svd
/+dub.sdl:
dependency "lubeck" version="~>1.5.4"
+/
import std;
import mir.ndslice;
import kaleidic.lubeck;
void main()
{
double[2] x_1 = [93,-7];
double[2] y_1 = [63,0];
double[2] x_2 = [293,3];
double[2] y_2 = [868,-6];
double[2] x_3 = [1207,7];
double[2] y_3 = [998,-4];
double[2] x_4 = [1218,3];
double[2] y_4 = [309,2];
auto A = [
-x_1[0], -y_1[0], -1, 0, 0, 0, x_1[0]*x_1[1],
y_1[0]*x_1[1], x_1[1],
0, 0, 0, -x_1[0], -y_1[0], -1, x_1[0]*y_1[1],
y_1[0]*y_1[1], y_1[1],
-x_2[0], -y_2[0], -1, 0, 0, 0, x_2[0]*x_2[1],
y_2[0]*x_2[1], x_2[1],
0, 0, 0, -x_2[0], -y_2[0], -1, x_2[0]*y_2[1],
y_2[0]*y_2[1], y_2[1],
-x_3[0], -y_3[0], -1, 0, 0, 0, x_3[0]*x_3[1],
y_3[0]*x_3[1], x_3[1],
0, 0, 0, -x_3[0], -y_3[0], -1, x_3[0]*y_3[1],
y_3[0]*y_3[1], y_3[1],
-x_4[0], -y_4[0], -1, 0, 0, 0, x_4[0]*x_4[1],
y_4[0]*x_4[1], x_4[1],
0, 0, 0, -x_4[0], -y_4[0], -1, x_4[0]*y_4[1],
y_4[0]*y_4[1], y_4[1]
].sliced(8, 9);
auto svdResult = svd(A);
auto homography = svdResult.vt[$-1].sliced(3, 3);
auto transformedPoint = homography.mtimes([1679, 128,
1].sliced.as!double.slice);
transformedPoint[] /= transformedPoint[2];
writeln(transformedPoint); //[4, 7, 1]
}
Re: Find homography in D?
On Sunday, 21 April 2024 at 14:57:33 UTC, Paolo Invernizzi wrote: Hi, Someone can point me to a D implementation of the classical OpenCV find homography matrix? Thank you, Paolo Kinda some work but it should be doable using DCV and mir.lubeck in theory DCV can compute, not sift or surf b, but similar features https://github.com/libmir/dcv/blob/master/examples/features/source/app.d Lubeck computes singular value decomposition https://github.com/kaleidicassociates/lubeck And this method but with mir ndslices https://medium.com/all-things-about-robotics-and-computer-vision/homography-and-how-to-calculate-it-8abf3a13ddc5
