calibrating webcam

edit

I'm trying to calibrate my webcam to remove distortions. I run

$ rosrun usb_cam usb_cam_node

Then this error and warning message is printed out:

[ERROR] [1384614141.059240716]: Unable to open camera calibration file [/home/robz/.ros/camera_info/head_camera.yaml]
[ WARN] [1384614141.060021982]: Camera calibration file /home/robz/.ros/camera_info/head_camera.yaml not found.

Not sure what that means. I wouldn't expect a calibration file to exist for a camera that I haven't been able to calibrate yet...

In any case, the node is still able to run despite the error and warning message. It publishes to a topic, and I can see it with image_view just fine. So then I run

$ ROS_NAMESPACE=usb_cam rosrun image_proc image_proc

Then, this error message is printed out:

[ERROR] [1384614331.794465524]: Rectified topic '/usb_cam/image_rect_color' requested but camera publishing '/usb_cam/camera_info' is uncalibrated

This is very confusing for me. I was under the impression that the image_proc node does the calibration. Why does it require a calibrated camera in order to run?