Date: Fri, 9 Oct 2009 17:33:53 -0700 (PDT) From: grow <george...@gmail.com>
Stefan, Thanks for your analysis of this. You asked about memory and responsiveness. My Mac has 5.5Gb of RAM ... when I have a large stitch to do I sometime restart the machine and re-open the Hugin project with only the Stitch tab open and no preview or anything else taking up memory ... that way I have about 4Gb of free memory at the start of the stitch. I have a box on the shelf with 2GB more RAM that I will install "soon" - probably this weekend - but I said that last weekend also. That will take the RAM to 7Gb (as I will have to take out 2x256Mb in order to fit the the 2x1Gb new cards). I will of course try my problematic Hugin projects after the upgrade to check whether it makes a difference. On responsiveness ... I haven't been systematic in measuring and plotting the times. These are all ROUGH NUMBERS FROM MEMORY - this is NOT the result of a carefully controlled and systematically logged analysis. But with that disclaimer out of the way it goes something like this ... If I launch a Hugin-stitch of one of the problematic projects at say 2,000 x 1,000 it will take a few minutes (typically I will set a tiny- test-stitch running ... switch windows to check email and the like ... and by the time I check back on Hugin it has finished) at 5,000 x 2,500 it might take perhaps 30 minutes ... (I go downstairs and watch an episode of The SImpsons ... when I get back to my desk the stitch is finishing up) at 8,000 x 4,000 it will run for about 2 hours (I go and cook and serve dinner) when it gets to 12,000 x 6,000 (I set it running before I go to bed and check before breakfast in the morning - either we have a good final image or an error report) when I check the file creation times it will have run for 6 or 7 hours! That's more than linear, but not by much -- N*sqrt(N). 5000x2500 = 12.5 MP, 0.5 hr = 25 MP/hr 8000x4000 = 32.0 MP, 2.0 hr = 16 MP/hr 12000x6000 = 72.0 MP, 6.0 hr = 8 MP/hr Or, based on the time for 12.5 MP, you'd expect the 8Kx4K to take 1.3 hours and the 72 MP to take about 3 hours if it were linear. If it were N^2, you'd expect 32 MP to take about 3~3.5 hours and 72 MP to take about 15 hours. If it were N*sqrt(N), the 32 MP should take about 2.0 hours and the 72 MP about 6.5~7 hours -- exactly what you're seeing. The 2 MP image should take about 0.064 hours, or 4 minutes. You're seeing consistent behavior all the way up. That's not usually a signature of memory thrashing -- usually when that happens you hit a wall, where above that point the time may well increase by orders of magnitude. So my intuition is that there is a square or possibly cubic progression in the processing time as the final image size increases. The processing time is proportional to something like n^3 where n is width of the image. It is NOT proportional to n^4 - so it is NOT the square of the area. Proportional to the cube of the width (linear dimension) appears to be correct based on these 3 or 4 data points, but since each pixel has to be processed I'd expect to calculate complexity based on the pixel area. Thus, N * sqrt(N). Perhaps the developers can explain why it's more than linear, but it's certainly not quadratic. -- Robert Krawitz <r...@alum.mit.edu> Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- http://ProgFree.org Project lead for Gutenprint -- http://gimp-print.sourceforge.net "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group. A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ To post to this group, send email to hugin-ptx@googlegroups.com To unsubscribe from this group, send email to hugin-ptx+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/hugin-ptx -~----------~----~----~----~------~----~------~--~---
