How to compute the homography

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Sushil Sharma
Sushil Sharma 2019-4-18
评论： Matt J 2019-12-28
Dear Community,
I have some issue to getting the trasnform image for homography
I want to apply the homography to an image, I do have homography martix from the general formulation
H = R+1/d*n*t'
H = rotation_matrix + t.* Normal
H =
0 -1.0000 0
-0.3420 0 -0.9397
5.9397 5.0000 4.6580
The basic concept of idea is to trying get image from vitrual camera, so the question I that how I can get the image from virtual camera ?
As you can see figure below , I have perspective image but I want to use inverse perspective mapping
Thanking you so much
3D2D.jpg

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采纳的回答

darova
darova 2019-4-19
Hi, that green trapezoid is what you want. Can be found as line intersections of plane
mmm.png
But having all those point on a plane (in 3D) dont know how to convert them into 2D (to get that trapezoid in XY):
mm1.png
And how to convert image (pixels position) having that trapezoid?
mm2.png
See attached files
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darova
darova 2019-4-21
Create vectors Nx, Ny first:
NX = cross([0 0 1],-NZ); % camera X-axis
NX = NX/norm(NX);
NY = cross(NX, NZ); % camera Y-axis
NY = NY/norm(NY);
Then using dot product convert each point in 2D:
Where, P = (x,y,z) - point on plane
Untitled.png
Sushil Sharma
Sushil Sharma 2019-4-21
Thank you so much darova for your answer,
I get some idea, now I understand how to deal with situation,
Really apppericate for your help,
I wish in future you will clear my doubt as you did now
Thanks in advance

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更多回答（1 个）

Matt J
Matt J 2019-4-19
tform = projective2d(H);
newImage = imwarp(oldImage,tform);
  2 个评论
Omar Ali
Omar Ali 2019-12-28
how i can apply it on input image?
Matt J
Matt J 2019-12-28
That's what this line does
newImage = imwarp(oldImage,tform);

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