By the way, just as a test I've just done a stitch of 120 overlapped raw files (on my 12 core 48 GB system with SSD array, 200 history steps configured). I first started Camera Raw on them, set development parameters to6144 x 4096 x 16 bits/channel, and chose [Done]. Then I started Photomerge, selected the raw files, and started Task Manager and an Explorer window to watch the resource usage mount. At 3 minutes in, Photoshop is converting raw files and memory usage is mounting at 15 GB. Photoshop Tempxxxxxxxxxxx Scratch files total 18 GB at this point. 5 minutes: RAM 19 GB, scratch 23 GB. 7 minutes: RAM 24 GB, scratch 29 GB. 8 minutes: Align Selected Layers Based On Content begins. RAM 27 GB, scratch 33 GB. 19 minutes: Aligning Layer IMG_xxxx.CR2 begins. RAM 28 GB, scratch 34 GB. 20 minutes: Aligning Layer continues, RAM 31 GB, scratch 38 GB. 25 minutes: Aligning Layer continues, RAM 43 GB, scratch 57 GB. 29 minutes: Generate Output Panorama begins. RAM 46 GB, scratch 104 GB. 31 minutes: Move steps appear in History. RAM 47 GB, scratch 122 GB. 32 minutes: Canvas Size begins. RAM 47 GB, scratch 123 GB. 34 minutes: Blend Selected Layers Based on Content begins. RAM 47 GB, scratch 124 GB. 39 minutes: Panorama completed. RAM 46 GB, scratch 111 GB (in 3 files). As you can derive from the above, at about 29 minutes, it would have been beneficial to have even more RAM. Notes: On a multi-core machine Camera Raw is quicker to convert the files first, as it multi-threads. I should have done the stitch as a two-step process for better speed. That would have cut the first 8 minutes in half at least. Converting to 8 bits/channel instead of 16 would have yielded half-sized data and probably sped up the process significantly, perhaps keeping Photoshop from going heavily into the scratch files. Final pano was about 42000 x 15000 pixels (a mere 630 MP). -Noel
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