# How to get the projection matrix from odometry/tf data ?

Hello,

I would like to compare my results of visual Odometry with the groundtruth provided by the KITTI dataset. For each frame in the groundthruth, i have a projection matrix. For example:

```
1.000000e+00 9.043683e-12 2.326809e-11 1.110223e-16 9.043683e-12 1.000000e+00 2.392370e-10 2.220446e-16 2.326810e-11 2.392370e-10 9.999999e-01 -2.220446e-16
```

Here the instructions provided by the readme:

Row i represents the i'th pose of the left camera coordinate system (i.e., z pointing forwards) via a 3x4 transformation matrix. The matrices are stored in row aligned order (the first entries correspond to the first row), and take a point in the i'th coordinate system and project it into the first (=0th) coordinate system. Hence, the translational part (3x1 vector of column 4) corresponds to the pose of the left camera coordinate system in the i'th frame with respect to the first (=0th) frame

But I don't know how to produce the same kind of data for me. What I have for each frame in my case:

- The Tf transformation from the init_camera (the fix one from the (0,0,0)) to the left camera which is moving. So I have the translation vector and the quaternion rotation.
- The odometry data: the pose and the twist
- Camera calibration parameters

With those data, How I compare with the groundtruth ? So I need to find the projection matrix from the data above but don't know how to do it.

Can someone help me ?

Thank