How can I transform the jpg/bmp picture to a ROS .pgm map
I have a map of school's square generated by a GPS measuring instrument. The size of the square is 71.27m * 59.98m actually and is 71.27mm * 59.98mm in the CAD diagram.
And now I want to use this map as the navigation map based on ROS. The resolution unit of pgm map in ROS is usually 0.05m/pixel. However, the resolution of the .jpg picture is 144dpi*144dpi.
How can I transform the jpg/bmp picture to a ROS .pgm map? I know this transformation must properly be scaled so that one pixel in my map matches the resolution setting in AMCL. I have tried to make the change by Photoshop but failed.
So can you tell me the details about the change?
Thank you.