Re: [Gimp-user] tips on working with gigantic files?

[Casey Connor <gimp-user-list caseyconnor org>]

> I don't think this will solve the problem you described, but I have
> found that clearing the undo history after every operation done on open
> files frees a lot of memory in cases where there is /almost/ too much
> data for the system to cope with.

Thanks, great tip -- As you say, I think it might not help here because 
I'm opening the file and immediately trying to export (i.e. no undo 
history) but that's great to keep in mind for the future.

> Another possibility:  Crop the images you are trying to merge down to
> just the bits that overlap, process those, then add the cropped parts
> back in.

Ah! Yes! I don't think I can combine them in gimp (due to RAM), and I 
don't think I can even crop the image now (same RAM overflow issue) but 
I bet I can crop to the overlap areas, do the overlap, export that, and 
then combine the three sections (top, overlap, and bottom) with the 
"montage" command. Thanks for the insight!

@Ken & @Liam Re: swap -- I did try this with a 16GB swap enabled and it 
never seemed to swap; but I'll try it with overcommit enabled as Liam 
suggested (you implied that that will trigger GIMP to fork the PNG 
export?). Currently, when it maxes out on RAM, everything slows to a 
crawl; as in, moving the mouse causes the mouse to update its position 
once every few seconds; takes minutes just to move the mouse to the 
corner of the screen, etc. GUI interaction (e.g. trying to close a 
window or switch to a v-term) doesn't seem possible, no matter how long 
I wait. In other words, the system is brought to its knees. Is that what 
heavy swapping can look like, and what I should expect even if 
overcommit is enabled? I just want to know when I should let it go 
overnight and expect that it's slowly working through the file, and when 
it's actually just spinning wheels and not getting anything done...

I will also play with tile cache size and so forth (it has been at 8GB; 
undo history was also at 8GB, but again, I was just opening and then 
exporting...)

@Rick:

> Just out of curiosity, why such a huge file? What do you intend to do 
> with the finished product if you could get your computer to work (if 
> you don't mind me asking)? 

Very fair question. :-) I just wanted to make a zoomable 'gigapixel' 
image for the heck of it. No true demand that it be so huge. Maybe I'll 
print it large-scale some day if it turns out well. For now I'm mainly 
just honing my skills on the techniques and learning what my computer 
can handle. (And the only reason it's sliced in two parts is that hugin 
can't write out the image in one piece without running out of RAM.)

Thanks, everyone, for the help,
-c