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I’m curious

Maximum number of images?

What's the maximum number of images we can add to one synth? Is it theoretically possible to map every photo on earth into one big synth that covers the entire planet, or are there scalability issues to consider?
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  • EMPLOYEE
    I’m thankful
    Photosynth will give you a warning if you try to synth more than 300 images together, but it will grind away if you ask it to. The promotional videos suggest synthing everything on the web, but there are some performance limitations here today. I expect the product to get more and more powerful in this way in the future. The priority probably depends on the needs and desires of the users.
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  • It depends on the available memory of your machine. I have a machine with 4 cores, 4GB of RAM and a 300G HD. I can process synths over 500 photos, but have had issues trying anything over 600.
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  • I’m excited
    Cool so it's a local thing then? Are there any tips for increasing performance?
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  • I've read that Photosynth is optimized to take advantage of multiple-core processors. So if you have, or can upgrade to, a Core Duo or a Quad cpu, it won't necessarily work 2x or 4x as fast, but there would definitely be a noticeable improvement. It's probably pretty important to have at least 1GB of RAM. On my machine, 2GB and a Core Duo 6300 (1.86GHz), during the main phase of the synthing, I run out of processing speed (it's 100% utilized for several minutes) long before I run out of memory.

    If MS can manage the server side of Photosynth well enough, keeping it online and available full time, it could be enough fun to persuade a LOT of people to upgrade their CPUs.
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  • I’m amused
    i am current processing 2027 pictures on a quad core with 4GB ram and 300GB hd, i needed to give it 50GB of swap space but it seems to be working.

    But there is one littel down side, it takes realy realy realy long to process, its now calculating for more then 5 hours... but we will see!
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  • xhoy, can you post the time it took for your synth to be calculated. And how did you find out how much swap space the process needed? Maybe you can look in the log file to what stage he's already done:
    Image conversion,
    Feature extraction,
    IndexFeatures,
    PredictImages,
    ChoosePairs+MatchPairs,
    Optimization,
    Uploading synth.bin&collection.dzcz

    Here are times for one of my synthes from the log file [all times in seconds]:
    Pentium M 1,4 GHz, 512MB RAM, swap ~1,2GB - 279 images
    16:05:08 VtApp: Start
    16:19:42 VtApp: Image conversion time: 873.4
    16:51:13 VtApp: Feature extraction time: 1890.7
    16:55:22 VtApp: IndexFeatures time: 249.0
    17:42:22 VtApp: PredictImages time: 2818.8
    21:36:14 VtApp: ChoosePairs+MatchPairs time: 14032.0
    21:36:18 VtApp: Total feature matching time: 16851.5
    23:39:45 VtApp: Optimization time: 7397.0
    Synth 0 : 279 images, 47164 points
    23:52:12 VtApp: Uploading "synth.bin" file ... (996867 bytes).
    23:52:23 VtApp: Upload finished
    23:52:23 VtApp: Uploading "dzc" collection.dzcz (12796758 bytes).
    23:54:22 VtApp: Upload finished
    23:54:23 VtApp: Collection completed (96% synthy), but isn't avialable for viewing yet.
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  • I’m confussed...
    @jackH, just moments ago photosynth was using 3.5GB+ of memory and it broke down :(

    Tomorrow i need to buy some extra ram :)

    It started to calculate at 1600 it's now 0020 so, 8 hours? i look

    from the logs:
    00:06:38 vtApp: ChoosePairs+MatchPairs time: 16880.4
    00:07:13 vtApp: TotalFeature matching time: 23785.6
    00:07:13 HR test fail <>\ReconstructionState.cpp(435) hr(8007000e)
    00:07::13 HR test fail <>\Registration.cpp(976) hr(8007000e)
    exception SynthPipeline.cpp)(202) hr(0x8007000E)
    exception CollectionUploader.cpp(341) hr(0x80004004)

    so tomorrow new changes...
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  • My set up is:
    Core 2 Quad
    4gb of ram
    Nvidia Geforce 8800GTS 512

    I can do 655 no problem.. takes two or three hours, but it works.
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  • I just did 443 images from a 14 MP camera (1.97 GB). I didn't time it, but was probably a cuple of hours. AMD 4200+, 1GB ram, nVidia 8800 GS. Does the video card have anything to do with synthing?

    I think I need to look into a faster upload plan with Comcast, if such a thing exists :-)
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    • I'd bet a kidney that your GPU doesn't make a difference in generating the synth. In theory you may have an extra processor on your graphics card, but in practice writing general purpose algorithms that work on everyone's GPUs is extremely difficult. Programmers can't just compile code for a graphics processor, we need to design the software with the graphics pipeline in mind.
    • That's a great idea however - distributed computing projects such as Folding @ Home already make good use of modern GPUs that are many times faster than all-purpose CPUs for certain streamlined types of processing. There's probably similar elements of synthing that could be massively sped up using a GPU given the type of data and the work being done on it. As for now however, with the early stage of the development and how it's quite a small executable working through the internet, the only thing the GPU probably does is on the post-processing, display side.

      In any case I'm on a centrino laptop with a fairly weedy graphics system so I hope it's not strongly implicated yet!
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  • it is not the size of the image that maters, the number of images matter :)

    http://photosynth.net/view.aspx?cid=6... 337 images in less then 1 hour.

    And when you think about it, it is pretty logical, more pictures mean more features, more features mean more to compare, more time to calculate in total.

    Anyhow tomorrow a new day :)
    • Yes, but larger image might mean that PhotoSynth might find more "features" per picture. Anyways, I also think that the number of image is the more relevant factor. But as synthing takes so long and I have 1000pic synthes waiting to be progressed I'd like to know whether I can expect the synthing-time to be quadratic with the number of the pictures (or worse? or just linear?).
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  • Here are times for another synth from the log file [all times in seconds]:
    Pentium M 1,4 GHz, 512MB RAM, swap ~1,2GB - 267 images - 7,5h
    17:00:01 VtApp: Start
    17:13:10 VtApp: Image conversion time: 788.1
    17:51:40 VtApp: Feature extraction time: 2308.0
    18:01:48 VtApp: IndexFeatures time: 607.4
    19:07:42 VtApp: PredictImages time: 3943.1
    23:36:51 VtApp: ChoosePairs+MatchPairs time: 16141.8
    23:37:00 VtApp: Total feature matching time: 20094.1
    00:30:05 VtApp: Optimization time: 3190.9
    Synth 0 : 267 images, 45614 points
    00:37:49 VtApp: Uploading "synth.bin" file 00:40:15 VtApp: Collection completed (100% synthy), but isn't avialable for viewing yet.

    It is available for viewing now. But the log file didn't get updated:
    http://photosynth.net/view.aspx?cid=F...
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  • I’m happy
    Just managed 500 images x 10 MP on a P4 2.6 Ghz with 1 GB RAM. Had previously run out of memory trying for 1300 images. Mind you, the 500 took about 7 hours I think. http://photosynth.net/view.aspx?cid=4...
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  • Nice show BirdDog!

    I haven't been able to get anything much over 400 to work. Still trying...
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  • Oh, and I did upgrade to the fastest upload plan for comcast :-)

    My biggest obsticle seems to be memory, if I had to guess, but I don't want to go out and buy ram for an old machine.

    If anyone knows of some tweaking for an AMD 4200+ with 1 GB RAM on XP, I'd be interested in your suggestions! I want to sen a LOT more than 400 photos!

    I use NetLimiter to monitor my upload of images and I noticed it would start uploading almost immediately. On other creations I would see them hang for awhile and see no uploading. I found that rebooting between synth creation would solve this. I didn't reboot every time, just when I could see no uploading right away.
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  • Couldn't synth 900 photos on 32bit Vista with 3 Gb RAM. Had to install Server 2008 64bit to make it work.
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  • I’m amused once more by insane abuse of low hardware
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    Lol... this could be fun then, given what I'm trying on some limited hardware, and the times/results people have posted so far.

    I already knew it was going to be a complex/slow one, as I've called it Complex Lounge (Photosynth Abuse) :-D --- but now I don't know if it's going to work?

    Pentium M 1.73Ghz, 1Gb RAM, 1Gb swapfile (though I may now go off and set it to "windows managed size"!)... and a 512mb memory card filled with over 800 pics of a room with enough "features" to keep even the most ADHD scene analyser on-task to the end. The first 400 or so being reasonably high resolution/quality (5mp / medium compression, from an 8mp camera), but then stepping down twice for the next 2 sets of 200 (2mp then VGA, both high comp).

    Been going for about an hour and a half now, maybe 15 minutes ago it entered the "Matching images" stage. Doesn't seem to be affecting the actual performance much except when I switch programs, whereupon it starts hammering the HDD for a short while (it's rattling away a fair bit anyway). The start was about 5.30pm local time, so I guess it's not going to be finished by midnight, or perhaps even next morning. Had thought it was coping quite well as the process memory usage was "only" hovering around 250 to 400mb, but I've just noticed the total memory used is 1.6Gb (of 2.0)... and the process usage is up to 500mb. Which are the levels where for any other program I'd be getting quite worried and about to hit the bail-out buttons.

    (it's really shooting up now, I've had to pause it as the process is sailing towards 600mb, and windows says the pagefile size is too small - I've paused to go make the necessary changes. Luckily I recently deleted a load of stuff and defragged so there's spare room for it to grow, and windows lets you make it bigger (but not smaller :) without restarting)

    If it eventually works, I'll see you back here. Particularly if it all holds together properly, as it should be a relatively epic synth for an otherwise generic 10 x 20ft sitting room, hehe

    Wish me luck... haven't abused low end hardware like this since I last did 4 simultaneous 2-hour MPEG encodes on a duron 850... or wrote an entire graphics-heavy dissertation on a VGA-rez P60 laptop (in 2005). Its a stupid hobby but keeps me happy.
    • W00t w00t... It seems that as long as you have the memory and let it grind away, it's perfectly happy. If I'd left my pagefile at the same size, it might well have failed, but letting it grow a bit meant everything worked alright, if a bit slow.

      807 images, ~500mb done in about 10-11 hours (not sure what exactly, I can't find the log file, and thanks to some IRL drama with a friend of my brother getting alcohol poisoning I missed the actual endpoint - ran from about 17:30 to somewhere between 03:30 and 04:30) and a little over 8 hours of actual CPU time thanks to disc thrash, other apps being used, uploading, etc.
      Happily only 0.5Gb of the quota used (so it doesn't ultimately need 2x the original size), but only 68% synthy. Obviously there's more to the synthyness rating than just blanketing a room with a squillion photos.

      Going by the other Task Manager stats I read off after it finished, it peaked at a bit more than 700mb of (V)RAM used, and nearly 1.0Gb of swap. It may be accurate to say that it reads in ALL the photo data at once then works on it in RAM (or swap), as the process I/O (ie file read/write) figures went up to a certain amount fairly quick (8.6Gb read, 560mb written before it got halfway!) then stayed static for the rest of the synth.

      The progress bar doesn't seem to be at all linear though. It went reasonably quick through the first couple stages, then got to Matching Images and almost appeared to hang for more than an hour before it started to slowly, jerkily move again. At the point where I last saw it, it had moved up about 1/4 more of the bar in maybe three hours (to a total of perhaps 40%), but an hour later had completed. Not a great deal of helpful detail on it either - it has it's arbitary length vs the total available length, and says what part of the process it's at, but doesn't e.g. have "Matching images (327/807)" or whatever, which could be a useful guide.

      Right, now to see how it looks :)
    • (incidentally the total swap size went up to about 1.33Gb, so not a huge increase, but one that would have led to failure if it hadn't been allowed to go up; overall "commit charge" only went up to 1.71Gb that I saw, but probably peaked near 2.0Gb)

      http://photosynth.net/view.aspx?cid=D...

      Pretty good :) I'm especially impressed by how the point cloud works, even showing the proper location of bushes in the front garden (if you fly "through" the window), though having everything semi transparent in that way is occasionally a bit wierd (esp when "bright" objects are behind "dark" ones). Bit of a disappointment that certain things, in particular ones which I'd meant to be "highlights" of the whole affair and did a fair number of approach and tracking shots to make them synth in properly (as per the guide) just haven't (closeups of our strange light switch, the fireplace, flybys of various ornaments, etc). Oh well, they're still available in small 3D groups (seperated from the main set for no clear reason), or as single shots, via the picture list thing.

      What I would recommend is setting your camera on continual-shot mode and just holding down the shutter button, moving it a little bit after each click. The series I shot that way seem to have worked a fair bit better than taking them singly and lining up on the LCD for some reason, maybe there's more overlap or your hand moves more naturally.

      PS is there any way to slow down the slideshow playback? I tried using it, and though it was a decent way of getting views where I couldn't manually navigate to, it did spin through a bit too quickly for some pictures to load in as anything more than rather blocky thumbnails.
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  • I’m amused
    My largest synth has 1350 photos, took about 48hrs on a 2.6Ghz quad with 8Gb ram. I'm still trying to get it up to 1600 photos...

    http://photosynth.net/view.aspx?cid=7...
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