I used usbcam driver to run two usbcam nodes. They are:

/camera1/imageview /camera1/usbcam1 /camera2/imageview /camera2/usbcam2 /rosout

Topic includes: /camera1/usbcam1/camerainfo /camera1/usbcam1/imageraw /camera2/usbcam2/camerainfo /camera2/usbcam2/imageraw

Then I try to calibrate the camera1 first. I type this command: $ rosrun cameracalibration cameracalibrator.py --size 8x6 --square 0.108 image:=/camera1/usbcam1/imageraw camera:=/camera1/usbcam1

The calibration window opened.

Then I try to calibrate in stereo mode. I type this command: $ rosrun cameracalibration cameracalibrator.py --size 8x6 --square 0.030 right:=/camera2/usbcam2/imageraw left:=/camera1/usbcam1/imageraw rightcamera:=/camera2/usbcam2 leftcamera:=/camera1/usb_cam1

It failed to open up the window. No error messages. Pls help.