Goodness that's a lot of images. Is this a 360° pan? Is it, in fact, a Gigapan? I believe some of those use many thousands of source images, and special hardware to process them, so 160 images sounds reasonably doable.
This guy seems to be able to use Photoshop with a lot of source images, so have a look and see how he does it.
If I could only give you one piece of advice, it would be to have very large Scratch space. A terabyte drive for instance, and don't expect it to be a quick process.
Good luck, and show us your results.
thank you for your response. I am trying to put togethere a map and will print it on glass and hang it on the wall (120cmx80cm). I i have downloaded the maps basically as a ready-to-print pdf mulit A4 mosaic. i have cropped away unnessesary graffics and i am there for left with non-overlapping images. To fill in the "blanks" between the images i have downloaded two sets of staggared maps (purple and red), like shown a sample of below. I think i have done about the same thing suggested in the link you posted but without any success...
If you are making a composite with all these pictures that you are merging for a 120x80 glass print, I wonder if you can't reduce the size of the 160 images. I am not completely sure that 16Gb are enough memory to keep up with 160 images in high resolution.
What I am wondering is if every map that you are merging necessarily needs to be huge sized or if you can ease the merge by reducing the resolution of all 160 images. The result should be massive enough not to loose on quality when printed on glass.
Here are some links that I found, hope something helps
Let us know how it works!