# Obtaining camera matrix for estimating shape of moving object

I have an object that is moving parallel to a stationary camera. I would like to use Structure from Motion or Shape from Silhouette to obtain the 3D points of the object.

For that, I need to obtain the camera matrix P = K [R | t]. I know that I can calculate the intrinsic matrix K using the checkerboard technique. But how do I know the rotation and translation of the camera?

1. I know that the object is moving in a constant speed. Exactly 10cm per second. And I am taking one frame per second. Does that relate to the camera moving 10cm? That would mean that the x value of the translation vector t is incremented by 10 for each image. The second image would therefore have the translation vector (10 0 0)

2. As the camera is stationary and the object moves parallel to the camera I am guessing that the rotation matrix is the identity I for each image.

Is my thinking correct?