How can I add a camera publishing to a ros topic from an sdf file

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I am working on simulating a quadcopter using the px4 sitl simulator and I want to add a camera which publishes images to a ros topic. The simulator contains a quadcopter model derived from the rotorS model.

But unlike the original rotorS model, the quadcopter model is described using an sdf file rather than a urdf file. Although I understood how to add a ROS topic publishing camera using the URDF file, I did not understand how to do the same using sdf files.

I am pasting the sdf file here, please tell me how I can add a camera which publishes to a ros topic by editing this sdf file. C:\fakepath\iris.sdf