Problem with XYZ points obtained
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Hello,
I'm trying to get the XYZ coordenates of the world using the CameraCalibrator app from 200 segmented images obtained from the capture of an object pointed with a laser line and positioned on a platform that rotates 1.8 degrees (by capture) to subsequently generate a 3d model.
To calculate the calibration matrix with the rotation of the object, I used the following lines of code:
%%
angleX = 0;
angleY = stp*(1.8); >> stp is number of step of the platform
angleZ = 0;
Rx = rotx(angleX); Ry = roty(angleY); Rz = rotz(angleZ);
Rb = Rx*Ry*Rz;
tx = 0; ty = 0; tz = 0;
tb = [tx ty tz];
MPb = [Rb zeros(3,1); tb 1];
Rt = [RotationMatrix; TranslationVector];
MC = Rt*IntrinsicMatrix;
P = MPb*MC;
P = P';
%%
after that, with the points (u, v) obtained from the segmented image, I calculate the XYZ points of the world using the following lines of code:
%%
% (u*P31 - P11)X + (u*P32 - P12)Y + (u*P33 - P13)Z + (u*P34 - P14) = 0
% (v*P31 - P21)X + (v*P32 - P22)Y + (v*P33 - P23)Z + (v*P34 - P24) = 0
for i = 1:length([u,v]) >> this is the cycle only for an image
A = [(u(i)*P(3,1) - P(1,1)) (u(i)*P(3,2) - P(1,2)) (u(i)*P(3,3) - P(1,3));
(v(i)*P(3,1) - P(2,1)) (v(i)*P(3,2) - P(2,2)) (v(i)*P(3,3) - P(2,3))];
b = [-(u(i)*P(3,4)) + P(1,4);
-(v(i)*P(3,4)) + P(2,4)];
x = pinv(A)*b;
XYZ(i,:) = x;
end
%%
When I plot the points obtained (plot_points_XYZ.png), it doesn't resemble the real shape of the object (Cap_cam1_step_01.png).
What am I doing wrong?
Thank you for your help
Rod Hid
P.S: Are the distortion values incorporated into the calculations of the intrinsic matrix, rotation matrix and translation vector delivered by the CameraCalibrator app?
17 个评论
Adam Danz
2019-5-9
I formatted your code. In the future, please use this button to add formatted code.
Rod Hid
2019-5-9
darova
2019-5-9
Can you please attach your data?
Rod Hid
2019-5-10
darova
2019-5-10
Can you please attach this data in another .mat . Can't read calibrationSession.mat (maybe i have older MATLAB version). Attach a few images also (not all)
TranslationVector = cameraParams.TranslationVectors(1,:);
RotationMatrix = double(cameraParams.RotationMatrices(:,:,1));
IntrinsicMatrix = cameraParams.IntrinsicMatrix();
I think something is wrong here:
img = imread(imgname); %Cargar imagen esqueletizada
[u,v] = find(img == 1); % u,v - vectors of 1xn length (rows)
for i = 1:length([u,v]) % has to be 1:length(u)
% some operations with u and v
end
Rod Hid
2019-5-10
darova
2019-5-10
Can you please attach those matrix in separate files
TranslationVector = cameraParams.TranslationVectors(1,:);
RotationMatrix = double(cameraParams.RotationMatrices(:,:,1));
IntrinsicMatrix = cameraParams.IntrinsicMatrix();
Rod Hid
2019-5-11
darova
2019-5-11
I changed diagonal elements that respons for scale
IntrinsicMatrix(1) = IntrinsicMatrix(1)/0.8;
IntrinsicMatrix(5) = IntrinsicMatrix(5)/2.1;
How did you obtain those matrix?
darova
2019-5-14
honestly, don't know
Rod Hid
2019-5-15
darova
2019-5-15
I didn't, just intuition
Rod Hid
2019-5-17
darova
2019-5-17
What do you mean? The answer is in your question
Rod Hid
2019-5-17
darova
2019-5-17
I didn't know those are focal length. Just saw that image and tried to change fx, fy
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