I would also like to know the limits for Panoramas from RAW files. I tried 6 RAW D810 files and it worked. I am now trying 36 RAW D700 files and it has been running for a hour and not completed the preview - has not failed yet. I generated a panorama from the 36 RAW D700 files running Lightroom 5 and Photoshop CS6 without any problems.
It seems to me that this will be dependent on the amount of RAM installed in the computer.
I've been having a similar problem. I'm photographing with an automatic pano head. When the new LR works, I'm very happy with the results. Also making panos in LR fits well into my workflow. But it takes much longer than the software that came with my panorama hardware or Microsoft's new (and free) Image Composite Editor. The non-adobe options are also nice in terms of showing the order prior to starting a stitch- since if there's a problem it will be apparent before spending all that time. I'm not sure when there is a problem if it's because of a maximum file size, number of images or what. But it really is frustrating to wait an hour to find that LR can't stitch a pano that even freeware can. Hopefully some of the bugs will be worked out soon!
The Pano with 36 D700 RAW files did complete - it ran for several hours. I would like to know what is required to reduce run time to an acceptable value.
What might help depends on what is slowing things down:
Are things slow because your computer is low on memory and LR is having to use virtual-memory instead of RAM? Getting more RAM would help.
Are things slow because LR is creating a raw file as the result which requires more computation and inherently slower? Get a better computer and/or use different software that doesn't produce a raw file and can take stitch the results of LR-exported TIFs.
Are things slow because LR uses the GPU but your video card is old and not helping much? Get a better video card.
In answer to the original question about maximum panorama size, in a video about the new panorama process in ACR9 (same process as in LR), Julieanne Kost (an Adobe trainer) said that panoramas are limited to 64-hundred pixels in maximum dimension and 512MB whichever comes first. I think she probably meant 64-thousand pixels and 512MB. Perhaps the limits are different with LR than the ACR plug-in, I'm not sure.
The video I saw is on this page: http://petapixel.com/2015/04/22/adobe-releases-camera-raw-9-same-hdr-pano-and-gpu-upgrades -as-lightroom-cc/
I've been doing some testing today, I was looking for something fun to put on my blog. I chose a series of images to stitch- 48 in total made with my automated pano head. To be consistent I converted the images from RAW to JPG (one software can't use RAW) and ran through the software that came with my pano head, Microsoft's Image Composite Editor, and the latest and greatest Lightroom. The Gigapan Stitch software that came with the hardware took about 10 minutes to complete and had no real errors. Microsoft's ICE had trouble with the sky the first time around, but I found a setting that fixed it later. It took about 5 minutes to complete. In the end the two files are about 1.2 Gigabytes when opened in Photoshop and look very similar.
Lightroom on the other hand has been trying for a little over two hours and hasn't finished. I had one really good stitch on a smaller pano with the new LR. I really like how it fits in my existing workflow, and that the resulting file is "raw". But the last few stitching jobs I've tried were disasters and took forever. I let one run overnight. When I looked in the morning this is what I got (see attached.) And stitching won't run in the background so I'm sitting waiting to finish other work until LR completes.
The panorama from 36 D700 images was 246.8 megapixels and the DNG file is 863MB. This panorama ran for several hours before it completed. The panorama from 6 D810 files was 154.8 megapixels and the DNG file is 276MB. Lightroom is having problems with ATI Radeon Graphic Processors, so it is not enabled - don't know how much this would speed it up.
JimHess My PC spec. is AMD FX4100 Quard core 3.6Ghz. + DDR3 16GB BUS1600 + SSD Smasung256GB 850Pro + nVidia GTX550Ti it should be enough for running for another 3-5 years and with LR should b fine. Thx
PS. My pano files is a RAW from 7D
Any updates or solution to this issues?
I'm running LR 6.1 on a Windows 10 machine which has 16GB of RAM, AMD Phenom II x6 1100T processor, nVidia 760 GTX and a Samsung 850 Pro SSD, and a 4K monitor.
I've tried stitching 96, 18MP RAW photos, but LR took over 12 hours and the process bar didn't move (but Task Manager showed that LR as using 20% of CPU and 3GB of RAM). When I saw that there as no progress, I canceled the process and I've tried something smaller, 48 RAW photos, ... same thing. 24 RAW photos it took 3 hours to do them and when it finished it them, it stitched them totally wrong. instead of stitching them like 123456789, it did 789564321
Also, I have a 6 core processor, and the maximum LR is using of that processor's power is 20%