Hi,

I am trying to use a point grey camera with a jackal to capture images and process them by subscribing to the image topic in ROS.

Here is what I am doing:

• I have installed the point grey camera driver software on the ROS platform in the jackal.
• I launch the camera driver using roslaunch in one terminal.
• Once the camera driver is launched, the camera gets detected and the topics related to the point grey camera become available such as "camera/image_raw".
• I have a small program which does nothing but start ros and subscribe to the "camera/image" topic to get the data which is an array as per link:[http://docs.ros.org/api/sensor_msgs/html/msg/Image.html]
• A callback function collects the data and creates files.
• This is launched in a separate terminal using rosrun

My problem:

• The capture is slow and the files captured are big -- I am suspecting that this is because I have not done anything to restrict the frame capture rate and that this is to be adjusted in the driver parameters.
• When this program is running, ROS does not seem to respond quickly to the SIGINT interrupt -- I suspect this is because it busy trying to complete its write of the camera data which is big and slow.(??)
• The data is raw and from the documentation I am not able to see how to map the data to 'r', 'g', 'b' channel values to pixel coordinate and colour information.

I need advice regarding:

• How do I reduce the size of the files for the capture? How do I fix the frame sample rate? Can I change the subscription rate in the program so that the capture of data from the topic happens at a fixed rate?
• Do I have to convert the raw data into an openCV format to be able to distinguish colour and pixel information?
• What is the efficient way and topic to use and access camera data?
• Is the method of launching the camera driver software and the program correct?

I would really appreciate help and advise.

Thanks, rsmitha.