Camera Projection Matrix

[Yingliang]

Hello, I have three questions.
1. I'm trying to export camera locations but I don't know how.
2. And I try to export camera projection matrix, I get a .ppm file in which there is a 4 * 4 matrix, I support the projection matrix is 3*4, why is 4 * 4 in the ppm file?
3. I also export the external paras, and I get six numbers for each image, does these six numbers represent for 3 * 1 rotation vector
and 3 * 1 translation vector?

Thank you very much!

[Andrea Alessi]

Hello,

1. what do you mean by locations? If you're referring to the X,Y,Z position (the same one you see when right clicking a camera and selecting properties) you can do so by exporting their external parameters (or if you meant when exporting a mesh, you can do so by using the fbx file format)

2. The ppm file is composed by two parts:
the first part is a 3x4 matrix (ppm)
the second part (the last line) file is the camera calibration radial distortion (5 values, it's not a 4x4 matrix)

ppm is composed as A * rt , where rt is composed as [R T] and R is 3x3 rotation matrix and T is a 3x1 displacement vector

(also remember that you can export matrices for opengl in the same export dialog)

3. externals are exported as ImageName x y z a1 a2 a3 , so: image name, x y z position and first axis of rotation X, second axis of Rotation y, third axis of rotation Z

Andrea

[Yingliang]

Thank you very much, Andrea! You really help me a lot.