Recently I had to create a video DVD iso image from a bunch .VOB files using Linux command line. I found this extensive tutorial on both how to create and burn an image file using command line. Here is a quick summary.
First, create VIDEO_TS and AUDIO_TS folders, if you don't already have them. Apparently some DVD players will not play a DVD if it doesn't have this particular directory structure.
In my case I had just .VOB, .IFO and .BUP files with no directory structure, so I copied all files to VIDEO_TS folder and left AUDIO_TS empty.
To create ISO I used a mkisofs command like so:
$ mkisofs -dvd-video -o mydvd.iso -udf /path/to/filedir/
Where "mydvd.iso" is the name of my future ISO file and "/path/to/filedir/" is the directory containing my VIDEO_TS and AUDIO_TS folders.
Just a little while later my ISO image file was ready. Just in case I checked to make sure that VIDEO_TS.IFO file had the lowest sector number like so:
$ isoinfo -i mydvd.iso -l