How do you incorporate extrinsic calibration information of sensors?

[Akro]

Hello, I have used GTSAM for SFM but I haven't tried to incorporate multiple sensors before.

I'm confused on how I incorporate sensor locations/frames into the factor graph.

ex:

I have transforms:

base_link -> Camera1,

Camera1-> Camera2.

Camera1-> IMU1

Camera1-> IMU2

etc.

My goal is to estimate the state of base_link and the map using all the sensors + motion model.

For Ceres I used a simple transformat matrix, I don't understand how to do it in GTSAM.

Thank you.