camera model sdf file not found

[Tung1213]

I'm following the rmf_human_detector package to compile. It succeeds when using colon build to compile. But I run the .py file to detect the presence of the person, I got the error.

the error:
ERROR] [launch]: Caught exception in launch (see debug for traceback): "package 'image_proc' not found, searching:

the error says I have no camera node to use, But I go to the rmf_demos_assests package to find camera sdf file. I can't find it.
I wonder know guys how to use the camera. Thanks.