Does the size of the photo (megapixles) matter

  • 7
  • Question
  • Updated 11 years ago
I normally take pictures using the highest megapixles possible. What do you recommend as the size of the megapixles that we should be uploading?
Photo of phil

phil

  • 1 Post
  • 0 Reply Likes

Posted 11 years ago

  • 7
Photo of Jonathan

Jonathan, Official Rep

  • 98 Posts
  • 57 Reply Likes
At the risk of being cliche, Size doesn't matter.

Because of the Seadragon engine, we can handle big pics just as easily as small ones.
Photo of Sierra_Rambler

Sierra_Rambler

  • 11 Posts
  • 0 Reply Likes
Let me risk an answer that's not conflicting but from a different angle... if you take your images at a lower resolution, the process of synthing them together should go faster. Also you won't fill up your 20Gb storage quota as quickly. But if you have plenty of time and storage space, higher-resolution images will let you zoom in much farther in the photosynth viewer, to be able to check out finer details. I've been able to see details on passersby, read inscriptions on buildings, etcetera.
Photo of JackH

JackH

  • 43 Posts
  • 0 Reply Likes
For now I found it hard to manage to zoom into a high-res picture. I think the interface is better suited for having low-res (screen size) images - but more of them and from near to the object. So zooming into a high-res image gets replaced by choosing an image that shows a smaller fraction of the object.
Photo of Dane Jasper

Dane Jasper

  • 8 Posts
  • 1 Reply Like
JackH - does your mouse have a wheel?
Photo of bmaltais

bmaltais

  • 18 Posts
  • 4 Reply Likes
I also think that higher res is not necessarily required. A good size picture in large quantity should compensate for the lack of pixels. Simply make sure to snap a few good pictures up close to some objects for details. Especially given storage space and memory requirement on the client end.

On cool thing could be a distributed photosynth client that allow photosynth to leverage idle CPU cycles on users PC to synth large amount of pictures together. This could be done on a group basis where users allow other users in that group to use free CPU cycles to help compute synths.
Photo of Nathanael Lawrence

Nathanael Lawrence

  • 795 Posts
  • 55 Reply Likes
One thing that hasn't been pointed out in this thread yet that I've heard elsewhere is that the synther uses 1.5 megapixel (approximately) versions of your photos to find image features that it will then match.

What this means is that if you have a 2 megapixel camera and a 12 megapixel camera which are both zoomed to the same level and have equal fields of view, you can take a picture with each one and to the synther (at this point) it will not make much difference, since both photos will be matched based on a 1.5 megapixel version of themselves. As far as viewing them once online, however, the 12 megapixel version is, naturally, much nicer to look at.

As several of you have pointed out, using smaller photos will not require as much ram or space on your system drive as the synth constructs itself, but that is the only benefit that I can see.

JackH, what have you found difficult about zooming into large images? Are they not resolving quickly enough for you? For me, the zooming made possible by the SeaDragon tech is one of the best things about enjoying a synth.
Photo of markp

markp

  • 47 Posts
  • 3 Reply Likes
Sooooo.... in that case, if it can deal with the pics at their native resolution and display them nicely, and synths at about 1.5mpx (i'm assuming 1600x900, 1536x1024 or 1440x1080 depending on aspect?) --- how come one I did with a few hundred 2mpx images looks for all the world when displayed that they've been reduced to 400x300 or less? I originally didn't shoot at anywhere near my camera's top resolution (8mpx) but chose a setting I thought would give a good, clear result that could be zoomed in a little if desired, without using up megatons of storage space, processing power or upload time.

It's pretty obvious that a major resolution reduction has taken place, as it's of some artful documentary photos on display at my workplace (using a glass-sided corridor as a naturally well lit gallery, and including walks up and down said corridor with the not-entirely-successful intent that you can act as a virtual visitor strolling up and down) and the poor definition is immediately evident on viewing any of the photos themselves... some of them actually being difficult to make out properly now... and most particularly the notice giving information about the exhibition. It's on a standard piece of printer paper at about 14 or 16 point text, which I know is perfectly legible at 2mpx (1600x1200) as I used to use my first, 2mpx-maximum digital camera quite successfully as a low-tech document scanner for material printed on the same size paper but with smaller point sizes. The page as displayed via photosynth is utterly unreadable, it's just a blocky blurry mess, you can't even make out the title that's a couple points larger and in bold.

I was accepting of it maybe having to reduce the picture fidelity in order to cope with larger numbers of pictures or synths that were all-round more complex, and it being more an advert for the expo rather than a reproduction of it (its not like I have the copyright on the thing anyway - but it is being shown for free at a public access site, so all I'm really doing is teleporting people to that location via the internet) until I read the company blurb above saying that it should give a perfect reproduction of the original good-detail pictures. Now I'm wondering what's going on, and at which point the failure lies - within the app, or within the propaganda?

It's not just that they're needing a long time to load up on a slow connection or something, and therefore only getting so far through the uninterpretable -> vaguely recognisable -> blocky but obvious -> reasonable -> full resolution stages that are plain to see most of the time. It gets up to a somewhat blocky state and then "hangs" there without getting any clearer, even if left for some minutes, and the same occurs when you move on to a new picture - the only reasonable assumption is that's actually the resolution they've been stored at on the server. The point cloud is pretty awesome and easily recognisable as the place I have to walk up and down every working day, but the photo quality itself leaves something to be desired.

Any clues?
I'm not bothering to do my future big-synths in anything higher than this setting until we figure out what's up here :) and in fact I'll probably downconvert them to XGA to save more space. (Using VGA as source is a loser's game, I've found out that much)
(not that I would probably have done them in higher rez anyway, though my last one I took all at 5mpx before rendering down to XGA just to get a bit more sharpness in each pixel and reduce the effect of CCD noise)
Photo of Jonathan

Jonathan, Official Rep

  • 98 Posts
  • 57 Reply Likes
can you add the link to the synth you feel shows the images drastically below their uploaded resolution? I'd like to take a look.
thanks
Photo of Nathanael Lawrence

Nathanael Lawrence

  • 795 Posts
  • 55 Reply Likes
Jonathan, I'm fairly certain it's this one. The first photo doesn't seem to do too badly, but the none of the shots of the courtyard or the photos on the wall seem to resolve fully.
Photo of markp

markp

  • 47 Posts
  • 3 Reply Likes
Jon, Nate - yes, that one. Some of them do seem to load up OK if you leave them a while but others (e.g. as in my attachment) either never fully load, or are taking so damn long about it that no-one, even myself, will hang around long enough to allow them to do so. Also the initial load-up seems to take forever, enough so that I was motivated to comment on it in my synth description. Is it just overly complex and causing issues either on the server or the flash client? Or held on a server that's having load / connection issues that haven't yet been picked up on ..... or suffered untrapped processing / uploading difficulties that have caused this effect. (Possibly something to do with that unreadable info-page also winding up synthing to completely the wrong wall for reasons that can't easily be explained other than an all-out glitch - one that I think has also affected at least one of my other large synths in a couple of odd ways)

As before, I'm not hugely bothered by it as I largely achieved what I wanted to when embarking on the experiment, but if they are supposed to be loading up quickly into their full, 2 megapixel, medium-high ISO, slightly blurred glory, then it's definitely something that needs looking into!

Thanks...

(EDIT: ah... it's auto-reduced that ... if there's any way you can zoom into it, however, the effect should be plain... in fact i think it's slightly noticable even here - if only because of the rather stark jpg compression it's also added to the image. I measured it in Paint as displaying at 680x512 pixels or thereabouts (within the maximised 1024x768 window), and it's still distinctly blocky, so it may even be 320x240 rather than 400x300!)

PS that was after leaving it sit for a couple of minutes, when a couple other pictures in the set on the "walk" towards it appeared in much better definition after only ~10 seconds (still seeming a bit slow, but did get there) ... oddly my impression of the dark, translucent surrounding pics on some of the locations was that they were clearer than the one in the centre!
In fact, it still hadn't resolved after I'd saved that image and shut paint again.