OpenCV Q&A Forum - RSS feedhttp://answers.opencv.org/questions/OpenCV answersenCopyright <a href="http://www.opencv.org">OpenCV foundation</a>, 2012-2018.Sun, 31 May 2015 07:20:48 -0500Perspective Transform using Chessboardhttp://answers.opencv.org/question/62956/perspective-transform-using-chessboard/ Hey,
I need some help with this problem:
I have a camera that takes a picture of something on a horizontal plane with a specific angle.
That creates a perspective transform of this "something". And I would like to get this picture as if I would look down from top of it.
What I did already and one thing that I don't know how to do:
1. I placed a chessboard there.
2. I find the corners of the chessboard.
3. ???
4. cvGetPerspectiveTransform
5. cvWarpPerspective
My problem is point 3.
I have to find out Source and Destination Points which depend on the corners of the chessboard and the width of the picture that was taken, because they show the transformation.
Source is easy: (0,0), (Width, 0), (0,Height) and (Width,Height), because I want the whole picture to be transformed.
Destination however is difficult for me. I don't know how to find those points.
I want that the whole picture (Not just the part with the chessboard inside) is transformed within a single step.
Like in the picture below.
I would appreciate any help.
Greetings and my thanks in advance,
Phanta
![image description](/upfiles/14331120304698347.png)PhantaSun, 31 May 2015 07:20:48 -0500http://answers.opencv.org/question/62956/How can I find rotation angles (pitch, yaw, roll) from perspective transofmation coefficients?http://answers.opencv.org/question/22100/how-can-i-find-rotation-angles-pitch-yaw-roll-from-perspective-transofmation-coefficients/I have two 2d quads (each represented using 4 xy pairs), one of them is a perspective transformation of the other. How can I use these quads to deduce the rotations (pitch, yaw, roll) that caused the perspective distortion?
Notice that I used the cvGetPerspectiveTransform() which returns the perspective transformation coefficients in the form of a 3x3 matrix. I am able to use such coefficients to map a point from one space to another. However, it is the rotation angles which I'm concerned about knowing.
Any ideas?
Thanks, Hasan.has981Tue, 08 Oct 2013 05:32:31 -0500http://answers.opencv.org/question/22100/Eliminate scaling from perspective transformhttp://answers.opencv.org/question/15936/eliminate-scaling-from-perspective-transform/I would like to project an image to a textured wall. Using various techniques I was able to detect the wall plane, and now I just want to draw the image on that plane.
The plane itself is a quadrangle, and I was able to get a perspective transform matrix between the image and the wall plane, and use that transform to perform the projection. My only problem is that the image is scaled up to occupy the entire quadrangle of the wall plane. I would only like it to follow its perspective, without the changes in scale. Can I somehow eliminate the scaling from the transformation matrix, or is there any other method that would help?
Thank you!Rares MusinaSun, 30 Jun 2013 09:40:03 -0500http://answers.opencv.org/question/15936/