Questions for Pano experts

Discussion in 'Other Genres' started by GFFPhoto, Apr 6, 2013.

  1. GFFPhoto

    GFFPhoto Mu-43 All-Pro

    Feb 24, 2013
    I just tried my first panoramic with Huigin. Very easy to get a basic pano, but I have a few questions. I went for a level horizon, but that leaves me with a fisheye effect on the closer stuff and it looks a bit strange to my eye. How do you guys handle balancing the horizon and foreground. Any hints, suggestions, or neat tricks to experiment with are welcomed, Thanks in advance, and here is the pano:

    untitled-1-2-Edit.jpg by GFFPhoto, on Flickr
  2. mattia

    mattia Mu-43 Hall of Famer

    May 3, 2012
    The Netherlands
    There are a lot of different options for rendering panoramas, but most of the composition is down to taste. No different from shooting other landscapes. I tend to use medium wide to normal focal lengths (17 to 25mm MFT) and stitch 3 to 4 images (landscape) or 5-6 images (portrait). Wider lenses tend to cause me more grief with distortion.

    I always shoot full manual, preferably with a tripod but that rarely works out.
  3. GFFPhoto

    GFFPhoto Mu-43 All-Pro

    Feb 24, 2013
    Thanks for the feedback. I went back into the program and looked at the different rendering methods. Looks like all you can really do is move the distorted perspective around, but you can't eliminate it completely. For an open source free/share ware program, Hugin is pretty awesome!
  4. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Could this be due to the nodal point of the lens? What I mean is that I am guessing you are balancing it on the tripod mount, instead of the nodal point. Not an expert, just throwing out an idea of something I know causes distortion in panoramas.
  5. slothead

    slothead Mu-43 All-Pro

    Aug 14, 2012
    Frederick, MD
    I don't know the specific answer to your question and frankly never much cared because I like the effect! Your pano is very good by the way (to my eye). Perhaps mine are taken with fewer images (4-6 generally), don't really know.

  6. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Thanks for posting GFFPhoto. That's a terrific first effort!

    I've been a pano film shooter for years - Widelux 6, Hassi X-Pan. Have shot my first digital pano but haven't gotten Hugin yet. So I'm no digital expert.

    I get the same effect w/ the swing lens Widelux. It shoots 140∘ AOV w/ a 25mm swing lens on 35mm film.

    To review what you already know, the far horizon of your photo is straight & level as you had planned. It is the closer lake shore that is curved. This is the horizontal equivalent of converging verticals when a camera is pointed up or down. The more you rotate the camera & the wider lens you use, the worse this gets just like pointing up or down. Much less of this would happen if your camera stayed fixed & the lens could tilt/shift from side to side.

    In theory it should be possible to "correct" this in PP but not sure which of the software programs do that. I know that Photoshop asks if you are making a spherical pano (like yours) & does something w/ that during stitching. I thought Hugin has this same option? But "correction" would require the software to upsample the pixels and create/remove them to get everything straight.

    In another thread here about lens shift adapters, a photographer told me he prefers to use mechanical shift instead of a PP fix for this type of problem. He though he got better results that way with the architectural subjects he shoots. Something like that is why I bought the X-Pan but that imposes other kinds of limitations. The AOV is inevitably more limited for example. With the shortest FL lens it has a 90∘ horizontal AOV.

    So there are mechanical solutions, presumably software solutions or a combination of both. With the equipment you have, you could also limit the AOV & use longer FL lenses. Since this is fundamental characteristic of panorama photography, I'm sure software exists to address it but I'm not sure which, how easy it is to use & cost.

    Likewise there are several tilt/shift & shift lenses & adapters. Zork has a new ($$) shift adapters. Looks like mainly to put MF lenses on Nik/Can cameras. There seems to be a revised shift adapter by Kipon for Mu43 cameras but the first version got poor reviews. I may try it some day unless someone else posts negative review.

    Hope this helps.
  7. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    also GFFPhoto couple questions, what is the file size for your stitched photo? How long did it take Hugin to stitch it & how much RAM do you have on what kind of computer?

  8. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    BTW, I suspect the choice to use or not use a software solution to correct this type of distortion depends on how you expect to display the image as well as how well the software may perform. Making big prints would of course require better results than a web display. Don't know what is required for display on a large screen TV.

    Also at least in theory, having more images & more overlap should allow the software to do a better job of resampling to correct distortion.
  9. ptolemyx

    ptolemyx Mu-43 Veteran

    Jun 19, 2012
    Vancouver, BC
    I don't know how Hugin compares, but I've always had good success with Microsoft ICE (also free) -- it has several rendering/perpective correction methods, one of which will probably do what you need.
  10. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
  11. inkista

    inkista Mu-43 Veteran

    Jan 13, 2012
    San Diego, CA
    I'm not sure what you're talking about from the image that you posted, but mostly, the "fisheye" distortion has to do with the mapping you chose for the stitched pano. When you have a FoV that's large enough, things have to be warped in space to represent the scene on a flat plane. Different mappings can yield different types and amounts of distortion.

    In Hugin, the easy thing is to click on the GL Preview button, and then click on the Projection tab. Play with all the selections on the pull-down menu: cylindrical, equirectangular, etc. Rectilinear probably won't give you what you want, but sometimes it's worth a try. I tend to use Panini when I want to mitigate distortion. It's a good "midway" point.

    If you're talking about a bowed/curved horizon, fixing it in Hugin is super-easy. Again, in the GL Preview window, click on the Move/Drag tab. If you drag the whole panorama up/down, that will adjust the pitch of the virtual camera of the panorama. If you drag left/right that adjusts the yaw (really only useful for 360 panos), and if you right-click drag you adjust roll/rotation (really only useful for s-horizons and vertical lines in equirectangular 360x180 panos).

    There's also a "straighten horizon" button somewhere, but I forget where, since I just use the drag feature most of the time. :)
  12. inkista

    inkista Mu-43 Veteran

    Jan 13, 2012
    San Diego, CA
    No, the nodal point/parallax thing is about getting a good stitch, not about distortion. Parallax error can change the relative position of objects in member images, so that just warping the images cannot get features to match correctly. John Houghton's website has a great explanation of this:

    You typically only have to worry about it if there are features of interest close to the camera or if you're shooting indoors.
  13. GFFPhoto

    GFFPhoto Mu-43 All-Pro

    Feb 24, 2013
    First, thanks to everyone for the great feedback. This is a fantastic community!:smile::smile::smile:

    To answer your questions, the file is 126.7 MB (TIF), different experiments have created files ranged from about 70 MB to 260 MB (some of those files have further processing with LR or Color effex, not sure how much that adds). Hugin works fast, it took less than 2 minutes to auto align and the actual stitch was also less than 2 minutes, probably less than 90 seconds. I have an iMac running OSX 10.7.5 with 12 gig of RAM and a 3.1 GHz Core i5. The picture was 9 frames, shot handheld with 25%-30% overlap, and auto stitched with the Hugin assistant before reading any documentation. I'm impressed that the software was able to overcome my complete ignorance, so I'm very pleased with Hugin!

    I'm starting to dive into the online documentation and look at the different rendering methods. I still haven't seen options for manual correction (like lens correction in LR), but I will keep looking. Someone recommended a Microsoft product, also free. I don't know if that has a Mac version, it may be a PC only thing, but I might check it out.

    Again, thanks for the feedback!

    Edit: That article about parallax is great, thanks inkista!. I tend to jump in and try stuff before I know what I'm doing. After reading that, I'm surprised I got the results I did.
  14. jziegler

    jziegler Mu-43 Veteran

    Dec 15, 2012
    Salem County, New Jersey
    It is definately the settings that you choose in Hugin, which are probably the default.

    Here is one that I processed in Hugin a number of months ago (sorry, Nikon not m43) that does not show the distortion

    It is assembled from 10 shots, using a cylindrical projection. I think that you probably used a different projection type. Opening up my project again and changing the settings, it looks like it may be rectilinear? Try changing the projection type in the projection tab of the previewer, and see what you like.
  15. marcsitkin

    marcsitkin Mu-43 Top Veteran Subscribing Member

    Jan 24, 2013
    Harwich, MA USA
    Marc Sitkin
    I think you're horizon may be a bit off level, but the foreground curve looks like it's caused by vertical changes in the elevation of the road.

    Composing for a successful pan is as much about choosing the spot you stand as anything else. Forward/backward is as important as left/right.

    Here's a link to my website, which has a variety of pans I've done over the years. I'll be happy to answer any questions you might have. If you click on the link to my blog once you are there, there are a couple articles describing how a made two pans.

    Best of luck, it can be challenging but also rewarding.
  16. inkista

    inkista Mu-43 Veteran

    Jan 13, 2012
    San Diego, CA
    In Hugin, it's all the lettered parameters and a bit cryptic. I've never quite wrapped my head around it, but, afaik, distortion and C/A correction are done via the a,b,c parameters. And you generally don't set them directly, but through the optimizer. Once you get the correction factors for a lens, you can save them off and reuse them for the next pano.

    It doesn't. Microsoft ICE is Windows-only.

    Hugin is my recommendation for where to start. If you end up doing a lot of stitching with it and require something even nicer, there's the commercial package, PTGui.

    I'm not. :) As I said up above, parallax really only becomes an issue if you're shooting nearby objects as well as far-away ones. With landscape shooting, you typically don't have anything that nearby (like the window he uses in the example). So parallax becomes much less of an issue. I've handheld a landscape pano made up of 27 shots (9x3 grid), and it stitched together just fine.

    It's when I shoot a spherical pano in a small space that I need a Nodal Ninja.

    DMC-G3. Rokinon 7.5mm fisheye. 6 shots around at 60-degree intervals in yaw, zenith, and nadir, 3 sets, bracketed at 2EV intervals and enfused.
    Interactive view. (requires Flash).