Just had an interesting problem creating a panorama in Lightroom.
I have a total of 20 Canon Raw files each about 22Mb in size. I selected all 20, and used the panorama facility inside LR to create a pano.
The net result took a while (my PC only has 8gb of RAM). However it managed to create a new file approx. 460Mb in size. It did however have a major flaw in the sky (presumably) at one of the joins. (incidentally, Photoshop did not create this flaw when I tried it later)
While I could have edited this flaw inside LR (or in PS), I decided to try and create 3 smaller panos from parts of the original 20 files, then merge the 3 panos together. Stage 1 of this process worked fine. I selected 7 images to create the first, then another 7, and finally the last 6 images. All this was done within LR.
I then selected the three small panos and tried to merge them inside LR. I get an error message in the Pano preview window saying Unable to merge the photos. Please cancel and review your selection.
If however I select the same 3 (small) panos and use the Photomerge in Photoshop, they happily create a merged image.
As far as I can see, the only differences between doing all 20 or just 3, is that the three intermediate panos are 16bit DNG’s, and the individual file sizes are greater
I cannot see any reference to the LR pano facility not doing 16bit DNG’s. Indeed, There is a Kost Tutorial showing merge to HDR (16 bit DNG) before merging to pano.
The same Kost tutorial mentions size limits of 64000 pixels or 512Mp (although they are not mentioned in the help file). The three intermediate panos are approx. 15,ooo pix els on the long edge and approx. 50 megapixels
Any suggestions why LR can’t complete this merge would be welcome.