I always looked at the DNG as an intermediate step: an intermediate storage unit where Lightroom stores the panorama for later editing (hence why it's called a "stack").  In other words, the result of the panorama function is stored in a DNG file so that you have LR's raw developing capabilities for the panorama.  In most cases, people will then open the resulting panorama (the DNG file) in LR and edit it for final printing.  You usually need to check/edit it for exposure, highlights, shadows, etc. once all the frames have been put together and crop out the "wobbly" edges on the top and bottom.  At that point, you save a final TIFF of your panorama.  I would say it is uncommon for people to take the raw output from the panorama command and try to print it.

Mike

Agree.  I've been working on the DNG problem behind the scenes.  So far, it looks like the LibRaw module that I'm using is just not designed to handle DNG files with that many pixels.  When I trace the loading of your ~24,000 x 5,000 pixel DNG files, LibRaw eats 1.6 GB of RAM on the load which (in a 32 bit process) leaves not much left to decode it.  A 24,000 x 5,000 pixel image should only use about HALF that amount of memory even with a 16 bit/channel full color linear DNG.  The strange thing is, it doesn't seem to run out of memory even at 1.6 GB of RAM used, but it returns an null image (0x0 resolution).  My only conclusion is that the DNG module wasn't designed for anything other than single raw shots.

I've emailed the company who makes the DNG support module and will see if they can find anything.  In the mean time, maybe you could just save your TIFFs in a folder separate from the DNG's so Qimage won't try to read those large DNG's along with the TIFFs.

Regards,
Mike